Becker's muscular dystrophy: Difference between revisions

Jump to navigation Jump to search
VisualWikitext
No edit summary
No edit summary
 
(12 intermediate revisions by the same user not shown)
Line 1: Line 1:
<br />{{SI}}
<br />{{SI}}
{{CMG}}; '''Associate Editor(s)-in-Chief:''' Moises Romo, M.D.
{{CMG}}; '''Associate Editor(s)-in-Chief:''' [[User:MoisesRomo|Moises Romo, M.D.]]


<br />
== Overview ==
 
Former "[[pseudohypertrophic muscular dystrophy]]", now Becker's muscular [[dystrophy]], is a [[Genetic disorder|genetic]] [[neuromuscular]] condition characterized by slowly progresive [[Muscle weakness|weakness]] and [[atrophy]] of [[Skeletal muscle|skeletal]] (mostly legs and pelvis) and [[cardiac muscles]].
== Overview[edit | edit source] ==
Former "[[pseudohypertrophic muscular dystrophy]]", now Becker's muscular [[dystrophy]], is a [[Genetic disorder|genetic]] [[neuromuscular]] condition characterized by slowly progresive [[Muscle weakness|weakness]] and [[atrophy]] of [[Skeletal muscle|skeletal]] (mostly legs and pelvis) and [[cardiac muscles]].  
 
== Historical Perspective[edit | edit source] ==
Becker's muscular [[dystrophy]] was first described by Peter Emil Becker, a German [[neurologist]], [[psychiatrist]] and [[geneticist]], in 1953 with his thesis called ‘‘Dystrophia Musculorum Progessiva: A [[Genetic]] and Clinical Investigation of the Muscular Dystrophies’’, after his work was interrumpted in 1942 due to [[World war|WWII]] recruitment. 
 
Before Becker, in the 1860's, French [[neurologist]] [[Guillaume Benjamin Amand Duchenne]] described in detail a slowly progessive [[Muscle weakness|muscular weakness]] in a boy, later known as [[Duchenne muscular dystrophy]].
 
The association between [[genetic mutations]] and Duchenne [[muscular dystrophy]] was made in 1986.
 
In 1987, [[dystrophin]] gene on [[X chromosome]] were first implicated in the [[pathogenesis]] of Becker's [[muscular dystrophy]].
<br />


== Pathophysiology[edit | edit source] ==
== Historical Perspective ==
The [[pathogenesis]] of Becker's muscular [[dystrophy]] is characterized by muscle [[Muscle weakness|weakness]] and [[pseudohypertrophy]] (mostly [[proximal]]), [[Hypertrophic cardiomyopathy|cardiomyopathy]], elevated [[CK]] and skelletal [[Deformity|deformities]].


Becker's muscular dystrophy is inherited in an [[X-linked]] recessive fashion.
* Becker's muscular [[dystrophy]] was first described by Peter Emil Becker, a German [[neurologist]], [[psychiatrist]] and [[geneticist]], in 1953 with his thesis called ‘‘Dystrophia Musculorum Progessiva: A [[Genetic]] and Clinical Investigation of the Muscular Dystrophies’’, after his work was interrumpted in 1942 due to [[World war|WWII]] recruitment.<ref name="pmid23576413">{{cite journal |vauthors=Zeidman LA, Kondziella D |title=Peter Becker and his Nazi past: the man behind Becker muscular dystrophy and Becker myotonia |journal=J. Child Neurol. |volume=29 |issue=4 |pages=514–9 |date=April 2014 |pmid=23576413 |doi=10.1177/0883073813482773 |url=}}</ref><ref name="urlGuillaume Benjamin Amand Duchenne de Boulogne">{{cite web |url=http://www.whonamedit.com/doctor.cfm/950.html |title=Guillaume Benjamin Amand Duchenne de Boulogne |format= |work= |accessdate=}}</ref>
* Before Becker, in the 1860's, French [[neurologist]] [[Guillaume Benjamin Amand Duchenne]] described in detail a slowly progessive [[Muscle weakness|muscular weakness]] in a boy, later known as [[Duchenne muscular dystrophy]].<ref name="pmid31789220">{{cite journal |vauthors=Mercuri E, Bönnemann CG, Muntoni F |title=Muscular dystrophies |journal=Lancet |volume=394 |issue=10213 |pages=2025–2038 |date=November 2019 |pmid=31789220 |doi=10.1016/S0140-6736(19)32910-1 |url=}}</ref>
* The association between [[genetic mutations]] and Duchenne [[muscular dystrophy]] was made in 1986.<ref name="HoffmanBrown1987">{{cite journal|last1=Hoffman|first1=Eric P.|last2=Brown|first2=Robert H.|last3=Kunkel|first3=Louis M.|title=Dystrophin: The protein product of the duchenne muscular dystrophy locus|journal=Cell|volume=51|issue=6|year=1987|pages=919–928|issn=00928674|doi=10.1016/0092-8674(87)90579-4}}</ref>
* In 1987, [[dystrophin]] gene on [[X chromosome]] were first implicated in the [[pathogenesis]] of Becker's [[muscular dystrophy]].<ref name="HoffmanBrown1987" /><br />


Becker's muscular [[dystrophy]] is caused by a [[mutation]] in the gene [[DMD]], one of the largest [[genes]] in humans. This [[gene]] encodes for the [[3685Y]] [[aminoacid]] protein called [[dystrophin]], wich can be found in [[Skeletal muscle|skeletal]] and [[Cardiac muscle cell|cardiac muscle]], among other tisues.  This [[mutation]] produces a truncated [[dystrophin]] [[protein]] that will translate into a decreased but not incomplete functionality (difference from [[Duchenne muscular dystrophy|Duchenne]]). Around 33% of patients with Becker's muscular dystrophy have [[de novo]] [[Mutation|mutations]]. Point [[Mutation|mutations]] and [[duplications]] appear mostly from [[spermatogenesis]] while deletions arise from [[oogenesis]] in most of te cases. 
== Pathophysiology ==


On microscopic [[Histopathology|histopathological]] analysis, endomysial fibrosis with fatty replacement of [[muscle]] in later stages, [[inflammation]], increased internal [[nuclei]], [[Myofiber|myofibe]]<nowiki/>r cleavage with [[necrosis]], and [[phagocytosis]] are characteristic findings of Becker's muscular dystrophy.<ref name=":0" />
* The [[pathogenesis]] of Becker's muscular [[dystrophy]] is characterized by muscle [[Muscle weakness|weakness]] and [[pseudohypertrophy]] (mostly [[proximal]]), [[Hypertrophic cardiomyopathy|cardiomyopathy]], elevated [[CK]] and skelletal [[Deformity|deformities]].<ref name="SarkozyBushby20143">{{cite journal|last1=Sarkozy|first1=A.|last2=Bushby|first2=K.|last3=Mercuri|first3=E.|title=Muscular Dystrophies|year=2014|doi=10.1016/B978-0-12-801238-3.05597-5}}</ref>
<br />
* Becker's muscular dystrophy is inherited in an [[X-linked]] recessive fashion.<ref name="urlBecker muscular dystrophy | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program4">{{cite web |url=https://rarediseases.info.nih.gov/diseases/5900/becker-muscular-dystrophy |title=Becker muscular dystrophy &#124; Genetic and Rare Diseases Information Center (GARD) – an NCATS Program |format= |work= |accessdate=}}</ref>
* Becker's muscular [[dystrophy]] is caused by a [[mutation]] in the gene [[DMD]], one of the largest [[genes]] in humans.<ref name="pmid24305447">{{cite journal |vauthors=Wicklund MP |title=The muscular dystrophies |journal=Continuum (Minneap Minn) |volume=19 |issue=6 Muscle Disease |pages=1535–70 |date=December 2013 |pmid=24305447 |doi=10.1212/01.CON.0000440659.41675.8b |url=}}</ref> This [[gene]] encodes for the [[3685Y]] [[aminoacid]] protein called [[dystrophin]], wich can be found in [[Skeletal muscle|skeletal]] and [[Cardiac muscle cell|cardiac muscle]], among other tisues.<ref name="pmid24305447" />  This [[mutation]] produces a truncated [[dystrophin]] [[protein]] that will translate into a decreased but not incomplete functionality (difference from [[Duchenne muscular dystrophy|Duchenne]]).<ref name="IannacconeCastro2013">{{cite journal|last1=Iannaccone|first1=Susan T.|last2=Castro|first2=Diana|title=Congenital Muscular Dystrophies and Congenital Myopathies|journal=CONTINUUM: Lifelong Learning in Neurology|volume=19|year=2013|pages=1509–1534|issn=1080-2371|doi=10.1212/01.CON.0000440658.03557.f1}}</ref> <ref name="pmid203012986">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>
*Around 33% of patients with Becker's muscular dystrophy have [[de novo]] [[Mutation|mutations]].<ref name="pmid236206492" /> Point [[Mutation|mutations]] and [[duplications]] appear mostly from [[spermatogenesis]] while deletions arise from [[oogenesis]] in most of te cases.<ref name="pmid203012983">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref> 
* On microscopic [[Histopathology|histopathological]] analysis, endomysial fibrosis with fatty replacement of [[muscle]] in later stages, [[inflammation]], increased internal [[nuclei]], [[Myofiber|myofibe]]<nowiki/>r cleavage with [[necrosis]], and [[phagocytosis]] are characteristic findings of Becker's muscular dystrophy.<ref name="SarkozyBushby20143" /><br />


== Clinical Features[edit | edit source] ==
== Clinical Features ==
Unlike [[Duchenne muscular dystrophy]], Becker's muscular dystrophy (BMD) [[phenotype]] presents at a later age, widely variable onset from early [[childhood]] to late [[adulthood]], most of them falling in [[puberty]] range. Most of the patients will requiere a wheelchair after age 16.
Unlike [[Duchenne muscular dystrophy]], Becker's muscular dystrophy (BMD) [[phenotype]] presents at a later age, widely variable onset from early [[childhood]] to late [[adulthood]], most of them falling in [[puberty]] range. Most of the patients will requiere a wheelchair after age 16.<ref name="pmid203012984">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>


Clinical presentation Becker's muscular [[dystrophy]] include:
Clinical presentation Becker's muscular [[dystrophy]] include:


* Progressive symmetric muscle weakness, with a predilection in proximal muscles (eg. pelvic, legs, shoulders)<ref name="pmid203012987" />
* Progressive symmetric muscle weakness, with a predilection in proximal muscles (eg. pelvic, legs, shoulders)<ref name="pmid203012984" />
*[[Congestive heart failure]]
*[[Congestive heart failure]]<ref name="SarkozyBushby20142" /><ref name="pmid203012988" /><ref name="pmid243054473">{{cite journal |vauthors=Wicklund MP |title=The muscular dystrophies |journal=Continuum (Minneap Minn) |volume=19 |issue=6 Muscle Disease |pages=1535–70 |date=December 2013 |pmid=24305447 |doi=10.1212/01.CON.0000440659.41675.8b |url=}}</ref>
*Calf [[hypertrophy]]<ref name="pmid203012987" />
*Calf [[hypertrophy]]<ref name="pmid203012984" /><ref name="pmid17162189" />
*[[Cramp|Cramping]] and [[muscle]] pain after exercise<ref name="pmid203012987" />
*[[Cramp|Cramping]] and [[muscle]] pain after exercise<ref name="SarkozyBushby20142">{{cite journal|last1=Sarkozy|first1=A.|last2=Bushby|first2=K.|last3=Mercuri|first3=E.|title=Muscular Dystrophies|year=2014|doi=10.1016/B978-0-12-801238-3.05597-5}}</ref><ref name="pmid17162189" />
* Flexion contractures<ref name="pmid203012987" />
* Flexion contractures<ref name="pmid203012984" /><ref name="pmid17162189" />
* Normal neck [[Flexion|flexor]] muscle [[Strength training|strength]] (differenting factor of BMD from [[Duchenne muscular dystrophy|DMD]])<ref name="pmid203012987" />
* Normal neck [[Flexion|flexor]] muscle [[Strength training|strength]] (differenting factor of BMD from [[Duchenne muscular dystrophy|DMD]])<ref name="pmid203012988">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>
 
There is an abcense of fasciculations, and this finding may exclude BMD<ref name="pmid203012987" />


[[CNS]] is rarely afected in Becker's muscular [[dystrophy]], for this reason, [[Intelligence test|intelligence]] is usually spared.
There is an abcense of fasciculations, and this finding may exclude BMD<ref name="SarkozyBushby20142" /><ref name="pmid203012988" />


Most of women are [[asymptomatic]] [[carriers]], with very rare cases presenting the classic [[Symptom|symptoms]].
[[CNS]] is rarely afected in Becker's muscular [[dystrophy]], for this reason, [[Intelligence test|intelligence]] is usually spared.<ref name="pmid203012984" /><ref name="SarkozyBushby2014">{{cite journal|last1=Sarkozy|first1=A.|last2=Bushby|first2=K.|last3=Mercuri|first3=E.|title=Muscular Dystrophies|year=2014|doi=10.1016/B978-0-12-801238-3.05597-5}}</ref>


<br />
Most of women are [[asymptomatic]] [[carriers]], with very rare cases presenting the classic [[Symptom|symptoms]].<ref name="pmid203012984" /><ref name="pmid203012986" /><br />


== Differentiating [disease name] from other Diseases[edit | edit source] ==
== Differentiating Becker's muscular dystrophy from other Diseases ==
Becker's muscular dystrophy must be differentiated from other diseases that cause skelletal and cardiac muscle afection, such as:
Becker's muscular dystrophy must be differentiated from other diseases that cause skelletal and cardiac muscle afection, such as:


* '''[[Duchenne muscular dystrophy]]'''. Presents with most of the symptoms of Beckers muscular [[dystrophy]] but with an earlier and more severe onset, most of them having [[Symptom|symptoms]] from age 3 ([[Gowers' sign|Gower's sign]]); by convention, if a patient with a suspected [[dystrophinopathy]] stops walking before 12 years of age, he has DMD. Another diferentiating factor is the normal strength of neck flexor muscles in BMD<ref name="pmid203012987" />
* [[Duchenne muscular dystrophy]]. Presents with most of the symptoms of Beckers muscular [[dystrophy]] but with an earlier and more severe onset, most of them having [[Symptom|symptoms]] from age 3 ([[Gowers' sign|Gower's sign]]); by convention, if a patient with a suspected [[dystrophinopathy]] stops walking before 12 years of age, he has DMD.<ref name="pmid243054473" /> Another diferentiating factor is the normal strength of neck flexor muscles in BMD.<ref name="pmid203012985">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>
* [[Limb-girdle muscular dystrophy|'''Limb-girdle muscular dystrophy''' '''(LGMD)''']]. Is a group of [[inherited]] [[autosomal]] conditions that are clinically similar to [[dystrophynopathies]] (muscle [[Muscle weakness|weakness]] and [[wasting]]) but occur in both sexes. They are caused by a [[gene]] [[mutation]] that encodes [[sarcoglycans]].
* [[Limb-girdle muscular dystrophy|Limb-girdle muscular dystrophy (LGMD)]]. Is a group of [[inherited]] [[autosomal]] conditions that are clinically similar to [[dystrophynopathies]] (muscle [[Muscle weakness|weakness]] and [[wasting]]) but occur in both sexes. They are caused by a [[gene]] [[mutation]] that encodes [[sarcoglycans]].
* [[Emery-Dreifuss muscular dystrophy|'''Emery-Dreifuss muscular dystrophy''' '''(EDMD)''']]. Is a [[Neuromuscular disease|neuromuscular]] disorder that may be inherited in an [[Autosomal chromosome|autosomal]] or [[X-linked]] mode. The classic clinical triad encompasses  incidious muscle [[Muscle weakness|weakness]] and [[wasting]] with predilection in the humero-peroneal distribution, joint [[Contracture|contractures]] in childhood, and cardiac afection that includes [[Palpitation|palpitations]], and syncope.
* [[Emery-Dreifuss muscular dystrophy|Emery-Dreifuss muscular dystrophy (EDMD)]]. Is a [[Neuromuscular disease|neuromuscular]] disorder that may be inherited in an [[Autosomal chromosome|autosomal]] or [[X-linked]] mode. The classic clinical triad encompasses  incidious muscle [[Muscle weakness|weakness]] and [[wasting]] with predilection in the humero-peroneal distribution, joint [[Contracture|contractures]] in childhood, and cardiac afection that includes [[Palpitation|palpitations]], and syncope.<ref name="pmid17162189" />
* [[Spinal muscular atrophy|'''Spinal muscular atrophy''' '''(SMA)''']]. Presents with muscle [[atrophy]], delayed [[weight]] and [[height]] gain, [[restrictive lung disease]], [[scoliosis]], [[Contractures|joint contractures]], and [[sleep]] difficulties. Is inherited in an [[autosomal recessive]] mode.<ref name="pmid203012982" />
* [[Spinal muscular atrophy|Spinal muscular atrophy(SMA)]]. Presents with muscle [[atrophy]], delayed [[weight]] and [[height]] gain, [[restrictive lung disease]], [[scoliosis]], [[Contractures|joint contractures]], and [[sleep]] difficulties. Is inherited in an [[autosomal recessive]] mode.<ref name="pmid203012985" /><ref name="pmid17162189" />
* [[Dilated cardiomyopathy|'''Dilated cardiomyopathy''' '''(DCM)''']]. Familial variants may be inherited in an [[Autosomal chromosome|autosomal]] ([[Dominant gene|dominant]] or [[Recessive gene|recessive]]), or an [[X-linked]] fashion. Presents with symptoms of [[dyspnea]] and poor [[Exercise stress testing|exercise tolerance]].
* [[Dilated cardiomyopathy|Dilated cardiomyopathy(DCM)]]. Familial variants may be inherited in an [[Autosomal chromosome|autosomal]] ([[Dominant gene|dominant]] or [[Recessive gene|recessive]]), or an [[X-linked]] fashion. Presents with symptoms of [[dyspnea]] and poor [[Exercise stress testing|exercise tolerance]].
* '''[[Barth syndrome]].''' Is an X-linked disorder characterized by prepubertal [[growth delay]] followed by a growth spurt, muscle [[Muscle weakness|weakness]], [[Cardiomyopathy, Dilated|cardiomyopathy]], [[neutropenia]],  and [[facial gestalt]].<br />
* [[Barth syndrome]]. Is an X-linked disorder characterized by prepubertal [[growth delay]] followed by a growth spurt, muscle [[Muscle weakness|weakness]], [[Cardiomyopathy, Dilated|cardiomyopathy]], [[neutropenia]],  and [[facial gestalt]].<br />


== Screening ==
== Screening ==
[[Prenatal testing|Prenatal molecular genetic testing]] is recomended in couples planning to [[Pregnancy|conceive]] and have family members who are afected by or are [[Genetic carrier|carriers]] of a dystrophinopathy.


[[In utero|In-utero]] fetal [[muscle biopsy]] has also been realized under couples request for [[fetuses]] with a high [[probability]] of beign affected and inconclusive [[genetic linkage]].
* [[Prenatal testing|Prenatal molecular genetic testing]] is recomended in couples planning to [[Pregnancy|conceive]] and have family members who are afected by or are [[Genetic carrier|carriers]] of a dystrophinopathy.<ref name="pmid2030129811">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>
 
* [[In utero|In-utero]] fetal [[muscle biopsy]] has also been realized under couples request for [[fetuses]] with a high [[probability]] of beign affected and inconclusive [[genetic linkage]].<ref name="pmid17041906">{{cite journal |vauthors=Deburgrave N, Daoud F, Llense S, Barbot JC, Récan D, Peccate C, Burghes AH, Béroud C, Garcia L, Kaplan JC, Chelly J, Leturcq F |title=Protein- and mRNA-based phenotype-genotype correlations in DMD/BMD with point mutations and molecular basis for BMD with nonsense and frameshift mutations in the DMD gene |journal=Hum. Mutat. |volume=28 |issue=2 |pages=183–95 |date=February 2007 |pmid=17041906 |doi=10.1002/humu.20422 |url=}}</ref>
It is important to identify females at risk to be [[heterozygous]] of a [[dystrophinopathy]], in order to manage possible [[Cardiomyopathies|cardiac]] complications; this can be done by [[Genetic testing|molecular genetic testing]], [[CK]] measurements, and [[Genetic linkage|linkage]] analysis.
* It is important to identify females at risk to be [[heterozygous]] of a [[dystrophinopathy]], in order to manage possible [[Cardiomyopathies|cardiac]] complications; this can be done by [[Genetic testing|molecular genetic testing]], [[CK]] measurements, and [[Genetic linkage|linkage]] analysis.<ref name="pmid17041906" /><ref name="pmid2030129811" />


<br />
<br />


== Epidemiology and Demographics[edit | edit source] ==
== Epidemiology and Demographics ==
The [[prevalence]] of Becker's muscular dystrophy is approximately 1-3 per 100,000 individuals.


The [[incidence]] of Becker's muscular dystrophy is approximately 3-6 per 100,000 male [[births]] worldwide.<ref name=":1" /><ref name=":2" />
* The [[prevalence]] of Becker's muscular dystrophy is approximately 1-3 per 100,000 individuals.
* The [[incidence]] of Becker's muscular dystrophy is approximately 3-6 per 100,000 male [[births]] worldwide.


=== Age[edit | edit source] ===
=== Age ===
Becker's muscular dystrophy is diagnosed in 85% of patients by age 25.
Becker's muscular dystrophy is diagnosed in 85% of patients by age 25.<ref name="pmid1673177">{{cite journal |vauthors=Bushby KM, Thambyayah M, Gardner-Medwin D |title=Prevalence and incidence of Becker muscular dystrophy |journal=Lancet |volume=337 |issue=8748 |pages=1022–4 |date=April 1991 |pmid=1673177 |doi=10.1016/0140-6736(91)92671-n |url=}}</ref>


=== Gender[edit | edit source] ===
=== Gender ===
Becker's muscular dystrophy affects mostly men, women are [[Genetic carrier|carriers]] almost exclusively (except rare situation).
Becker's muscular dystrophy affects mostly men, women are [[Genetic carrier|carriers]] almost exclusively (except rare situation).<ref name="pmid2030129813">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>


=== Race[edit | edit source] ===
=== Race ===
Becker's muscular dystrophy usually affects individuals of the hispanic race.<ref name="pmid19834452" />


Asian individuals are less likely to develop Becker's muscular dystrophy.<ref name=":3" />
* Becker's muscular dystrophy usually affects individuals of the hispanic race.<ref name="urlPrevalence of Duchenne / Becker Muscular Dystrophies | CDC">{{cite web |url=https://www.cdc.gov/ncbddd/musculardystrophy/features/key-findings-population-duchenne.html |title=Prevalence of Duchenne / Becker Muscular Dystrophies &#124; CDC |format= |work= |accessdate=}}</ref><ref name="pmid198344522">{{cite journal |vauthors= |title=Prevalence of Duchenne/Becker muscular dystrophy among males aged 5-24 years - four states, 2007 |journal=MMWR Morb. Mortal. Wkly. Rep. |volume=58 |issue=40 |pages=1119–22 |date=October 2009 |pmid=19834452 |doi= |url=}}</ref>
* Asian individuals are less likely to develop Becker's muscular dystrophy.<ref name="urlPrevalence of Duchenne / Becker Muscular Dystrophies | CDC" /><ref name="pmid198344522" />


== Risk Factors[edit | edit source] ==
== Risk Factors ==
Becker's muscular dystrophy is developed in the majority of cases from males who are born from [[genetic carrier]] mothers or by [[Mutation|spontaneous mutation]],<ref name="pmid23620649" /> there has not been any [[Risk factor|risk factors]] implicated for a [[DMD]] gene mutation.


Studies have found that several [[Genetics|genetic]] [[polymorphisms]] and [[Mutation|mutations]] may be a factor for Becker's muscular dystrophy progression, but further [[research]] is necessary to draw conclusions.
* Becker's muscular dystrophy is developed in the majority of cases from males who are born from [[genetic carrier]] mothers or by [[Mutation|spontaneous mutation]], there has not been any [[Risk factor|risk factors]] implicated for a [[DMD]] gene mutation.<ref name="pmid198344523">{{cite journal |vauthors= |title=Prevalence of Duchenne/Becker muscular dystrophy among males aged 5-24 years - four states, 2007 |journal=MMWR Morb. Mortal. Wkly. Rep. |volume=58 |issue=40 |pages=1119–22 |date=October 2009 |pmid=19834452 |doi= |url=}}</ref>
<br />
* Studies have found that several [[Genetics|genetic]] [[polymorphisms]] and [[Mutation|mutations]] may be a factor for Becker's muscular dystrophy progression, but further [[research]] is necessary to draw conclusions.<ref name="pmid27018093">{{cite journal |vauthors=Barakat-Haddad C, Shin S, Candundo H, Lieshout PV, Martino R |title=A systematic review of risk factors associated with muscular dystrophies |journal=Neurotoxicology |volume=61 |issue= |pages=55–62 |date=July 2017 |pmid=27018093 |doi=10.1016/j.neuro.2016.03.007 |url=}}</ref> <br />
== Natural History, Complications and Prognosis[edit | edit source] ==
== Natural History, Complications and Prognosis ==
The majority of patients with Becker's muscular dystrophy remain asymptomatic until adolescence.<ref name="pmid975594">{{cite journal| author=Emery AE, Skinner R| title=Clinical studies in benign (Becker type) X-linked muscular dystrophy. | journal=Clin Genet | year= 1976 | volume= 10 | issue= 4 | pages= 189-201 | pmid=975594 | doi=10.1111/j.1399-0004.1976.tb00033.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=975594  }}</ref>


Early clinical features include calf hypertrophy, difficulty rising from a chair, proximal muscle weakness, climbing stairs, sustaining balance, elevating arms, and in later stages heart failure.<ref name="pmid20301298" />
* The majority of patients with Becker's muscular [[dystrophy]] remain [[asymptomatic]] until [[adolescence]].<ref name="pmid975594">{{cite journal |vauthors=Emery AE, Skinner R |title=Clinical studies in benign (Becker type) X-linked muscular dystrophy |journal=Clin. Genet. |volume=10 |issue=4 |pages=189–201 |date=October 1976 |pmid=975594 |doi=10.1111/j.1399-0004.1976.tb00033.x |url=}}</ref>
* Early clinical features include calf hypertrophy, difficulty rising from a chair, [[Anatomical terms of location|proximal]] muscle [[Muscle weakness|weakness]], climbing stairs, sustaining [[Imbalance|balance]], elevating arms, and in later stages [[heart failure]].<ref name="pmid203012989" /><ref name="pmid23097603">{{cite journal |vauthors=Passamano L, Taglia A, Palladino A, Viggiano E, D'Ambrosio P, Scutifero M, Rosaria Cecio M, Torre V, DE Luca F, Picillo E, Paciello O, Piluso G, Nigro G, Politano L |title=Improvement of survival in Duchenne Muscular Dystrophy: retrospective analysis of 835 patients |journal=Acta Myol |volume=31 |issue=2 |pages=121–5 |date=October 2012 |pmid=23097603 |pmc=3476854 |doi= |url=}}</ref>
* The most common complications in Becker's muscular dystrophy are [[Cardiac failure|cardiac]] and [[Respiratory failure|respiratory]] failure, [[Pneumonia|pneumonias]], and in rare cases [[cognitive impairment]].<ref name="pmid975594" /><ref name="urlwww.mda.org">{{cite web |url=https://www.mda.org/sites/default/files/publications/Facts_DMD-BMD_P-211_0.pdf |title=www.mda.org |format= |work= |accessdate=}}</ref>
* [[Prognosis]] is generally poor, depending on [[spectrum]] of Becker's muscular dystrophy, but much better that [[Duchenne muscular dystrophy]]. In 2002, the [[Survival analysis|survival]] rate at age 20 was 60%.<ref name="pmid17162189" /><ref name="urlPathology Outlines - Becker muscular dystrophy">{{cite web |url=https://www.pathologyoutlines.com/topic/musclebeckermusculardystrophy.html |title=Pathology Outlines - Becker muscular dystrophy |format= |work= |accessdate=}}</ref>
* If left [[untreated]], the majority of patients with Becker's muscular dystrophy may die due to [[Cardiac failure|cardiac]] and [[Respiratory failure|respiratory]] failure in their mid-40's.<ref name="pmid203012989">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>
* Cradiac, respiratory, and orthopedic care has greatly improved in last years for patients with Becker disease, this, increasing the life span in these individuals.<ref name="pmid2030129814">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>


Cradiac, respiratory, and orthopedic care has greatly improved in last years for patients with Becker disease, this, increasing the life span in these individuals.<ref name=":4">{{Cite web|url=https://www.mda.org/sites/default/files/publications/Facts_DMD-BMD_P-211_0.pdf|title=Facts About Duchenne & Becker Muscular Dystrophies|last=Norton|first=Suzane|date=12/2009|website=Muscular Dystrophy Association|archive-url=|archive-date=|dead-url=|access-date=05/27/2020}}</ref><ref name="pmid230976032">{{cite journal| author=Passamano L, Taglia A, Palladino A, Viggiano E, D'Ambrosio P, Scutifero M | display-authors=etal| title=Improvement of survival in Duchenne Muscular Dystrophy: retrospective analysis of 835 patients. | journal=Acta Myol | year= 2012 | volume= 31 | issue= 2 | pages= 121-5 | pmid=23097603 | doi= | pmc=3476854 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23097603  }}</ref>
If left untreated, the majority of patients with Becker's muscular dystrophy may die due to cardiac and respiratory failure in their mid-40's.<ref name="pmid17932095">{{cite journal| author=Holloway SM, Wilcox DE, Wilcox A, Dean JC, Berg JN, Goudie DR | display-authors=etal| title=Life expectancy and death from cardiomyopathy amongst carriers of Duchenne and Becker muscular dystrophy in Scotland. | journal=Heart | year= 2008 | volume= 94 | issue= 5 | pages= 633-6 | pmid=17932095 | doi=10.1136/hrt.2007.125948 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17932095  }}</ref><ref name=":4" /><ref name="pmid203012984">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume=  | issue=  | pages=  | pmid=20301298 | doi= | pmc= | url= }}</ref>
Prognosis is generally poor, depending on spectrum of Becker's muscular dystrophy, but much better that Duchenne muscular dystrophy.<ref name="pmid203012983">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume=  | issue=  | pages=  | pmid=20301298 | doi= | pmc= | url= }}</ref> In 2002, the survival rate at age 20 was 60%.<ref name="pmid23097603">{{cite journal| author=Passamano L, Taglia A, Palladino A, Viggiano E, D'Ambrosio P, Scutifero M | display-authors=etal| title=Improvement of survival in Duchenne Muscular Dystrophy: retrospective analysis of 835 patients. | journal=Acta Myol | year= 2012 | volume= 31 | issue= 2 | pages= 121-5 | pmid=23097603 | doi= | pmc=3476854 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23097603  }}</ref>
<br />
<br />


== Diagnosis[edit | edit source] ==
== Diagnosis ==
 
The diagnosis of Becker's muscular dystrophy is made with a classic clinical presentation plus elevated [[Creatine kinase|CK]], [[Molecular genetic analysis|molecular genetic testing]], or [[muscle biopsy]].<ref name="pmid2030129816" />
=== Diagnostic Criteria[edit | edit source] ===


* The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met:
=== Symptoms ===
Symptoms of Becker's muscular dystrophy may include the following:


:* [criterion 1]
* [[Anatomical terms of location|Proximal]] [[muscle weakness]]<ref name="urlwww.mda.org" /><ref name="pmid23097603" />
:* [criterion 2]
* [[Myalgia|Myalgias]]<ref name="urlwww.mda.org" /><ref name="pmid2030129816" />
:* [criterion 3]
* [[Cramp|Muscle cramps]]<ref name="urlwww.mda.org" />
:* [criterion 4]
* [[Imbalance]]<ref name="urlwww.mda.org" /><ref name="pmid2030129816">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>
* [[Toe walking]]<ref name="pmid23097603" />
* Difficulty raising from a chair<ref name="urlwww.mda.org" /><ref name="pmid23097603" /><ref name="pmid2030129816" />
* Difficulty [[climbing]] stairs<ref name="urlwww.mda.org" /><ref name="pmid2030129816" />
* Difficulty raising the arms<ref name="urlwww.mda.org" /><ref name="pmid23097603" />
* [[Cardiac failure|Heart failure]]<ref name="urlwww.mda.org" />
* [[Dyspnea]]<ref name="pmid2030129816" />


=== Symptoms[edit | edit source] ===
=== Physical Examination ===
Patients with Becker's muscular dystrophy usually adopt a posture with shoulders held back, abdomen stuck out, and lumbar hyperlordosis.<ref name="pmid2760082" />


* [Disease name] is usually asymptomatic.
Physical examination may be remarkable for:
* Symptoms of [disease name] may include the following:


:* [symptom 1]
*Calf [[Hypertrophy (medical)|hypertrophy]]<ref name="urlwww.mda.org" />
:* [symptom 2]
*[[Gowers sign]]<ref name="urlwww.mda.org" />
:* [symptom 3]
*[[Cardiac arrhythmia|Arrythmias]]<ref name="urlwww.mda.org" />
:* [symptom 4]
:* [symptom 5]
:* [symptom 6]


=== Physical Examination[edit | edit source] ===
=== Laboratory Findings ===
An elevated [[Creatine kinase|CK]] is typical in Becker's muscular [[dystrophy]], with a peak around 10-15 years of age.<ref name="pmid243054472" />


* Patients with [disease name] usually appear [general appearance].
Other laboratory findings consistent with Becker's muscular dystrophy may be:
* Physical examination may be remarkable for:


:* [finding 1]
* Elevated [[Alanine transaminase|ALT]]/[[ASTL|AST]]<ref name="pmid243054472">{{cite journal |vauthors=Wicklund MP |title=The muscular dystrophies |journal=Continuum (Minneap Minn) |volume=19 |issue=6 Muscle Disease |pages=1535–70 |date=December 2013 |pmid=24305447 |doi=10.1212/01.CON.0000440659.41675.8b |url=}}</ref>
:* [finding 2]
* [[Myoglobinuria]] when strenous [[Physical exercise|physical activity]]<ref name="pmid170419062">{{cite journal |vauthors=Deburgrave N, Daoud F, Llense S, Barbot JC, Récan D, Peccate C, Burghes AH, Béroud C, Garcia L, Kaplan JC, Chelly J, Leturcq F |title=Protein- and mRNA-based phenotype-genotype correlations in DMD/BMD with point mutations and molecular basis for BMD with nonsense and frameshift mutations in the DMD gene |journal=Hum. Mutat. |volume=28 |issue=2 |pages=183–95 |date=February 2007 |pmid=17041906 |doi=10.1002/humu.20422 |url=}}</ref>
:* [finding 3]
* Normal [[Gamma-glutamyl transpeptidase|GGT]]<ref name="pmid26022459">{{cite journal |vauthors=Lee SH, Lee JH, Lee KA, Choi YC |title=Clinical and Genetic Characterization of Female Dystrophinopathy |journal=J Clin Neurol |volume=11 |issue=3 |pages=248–51 |date=July 2015 |pmid=26022459 |pmc=4507379 |doi=10.3988/jcn.2015.11.3.248 |url=}}</ref>
:* [finding 4]
:* [finding 5]
:* [finding 6]


=== Laboratory Findings[edit | edit source] ===
=== Hystopathology ===
[[Histological section|Histologic]] findings in Becker's muscular may be:


* There are no specific laboratory findings associated with [disease name].
* [[Atrophy|Atrophic]] small [[myofibers]]<ref name="SarkozyBushby20143" />
* [[Skeletal muscle|Muscle fibers]] [[necrosis]] and regeneration<ref name="SarkozyBushby20143" /><ref name="urlPathology Outlines - Becker muscular dystrophy" />
* [[Endomysium|Endomysial]] [[fibrosis]] and fatty replacement of [[muscle]]<ref name="SarkozyBushby20143" />
* [[Inflammation]]<ref name="SarkozyBushby20143" /><ref name="urlPathology Outlines - Becker muscular dystrophy" />


* A [positive/negative] [test name] is diagnostic of [disease name].
=== EMG ===
* An [elevated/reduced] concentration of [serum/blood/urinary/CSF/other] [lab test] is diagnostic of [disease name].
[[Electromyography|EMG]] in Becker's muscular [[dystrophy]], may reveal myopathic [[motor units]] with or without [[muscle membrane]] instability.<ref name="pmid243054472" /><ref name="pmid30356714">{{cite journal |vauthors=Naddaf E, Milone M, Mauermann ML, Mandrekar J, Litchy WJ |title=Muscle Biopsy and Electromyography Correlation |journal=Front Neurol |volume=9 |issue= |pages=839 |date=2018 |pmid=30356714 |pmc=6189315 |doi=10.3389/fneur.2018.00839 |url=}}</ref>
* Other laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].


* Creatine kinase (CK) is significantly elevated but not to the degree seen in DMD
=== Echocardiography ===
* Peak CK levels are usually found around 10 - 15 years of age
[[Echocardiography|Echocardiogram]] should be done at the time of diagnosis.<ref name="pmid30356714" /><ref name="pmid2030129817">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS |title= |journal= |volume= |issue= |pages= |date= |pmid=20301298 |doi= |url=}}</ref>
* ALT / AST may be elevated
* Can see occasional myoglobinuria following strenuous activity


=== Imaging Findings ===
There are no [[X-ray]] findings characteristic with  with Becker's muscular dystrophy, but [[scoliosis]] may be found.<ref name="pmid2760082">{{cite journal |vauthors=Smith AD, Koreska J, Moseley CF |title=Progression of scoliosis in Duchenne muscular dystrophy |journal=J Bone Joint Surg Am |volume=71 |issue=7 |pages=1066–74 |date=August 1989 |pmid=2760082 |doi= |url=}}</ref>   
<br />
<br />
=== Imaging Findings[edit | edit source] ===
== Treatment ==


* There are no [imaging study] findings associated with [disease name].
=== Medical Therapy ===


* [Imaging study 1] is the imaging modality of choice for [disease name].
* There is no definitive treatment for Becker's muscular [[dystrophy]]; treatment will be [[Multidisciplinary care|multidisciplinary]] depending on [[Comorbidity|comorbidities]]; the mainstay of therapy is [[supportive care]].<ref name="SarkozyBushby20144" />
* On [imaging study 1], [disease name] is characterized by [finding 1], [finding 2], and [finding 3].
* [[Corticosteroid medications|Corticosteroids]] have shown to improve strength in other [[dystrophinopathies]], but its efficacy on Beckers muscular dystrophy is uncertain. To measure improvement with [[corticosteroid]] therapy, [[timed muscle function tests]], [[pulmonary function tests]], and age at loss of [[independent ambulation]] are registered.<ref name="pmid2030129817" />
* [Imaging study 2] may demonstrate [finding 1], [finding 2], and [finding 3].
* The management of [[Scoliosis (patient information)|scoliosis]] is bracing and [[surgery]] in some cases.<ref name="urlPathology Outlines - Becker muscular dystrophy" />
* [[Beta-blockers]], [[ARBs|angiotensin II-receptor blockers]], and [[ACE inhibitor|ACE inhibitors]] are used to improve [[ventricular function]] in patients with Becker's muscular [[dystrophy]] when [[Ejection fraction|EF]] is less than 55%.<ref name="SarkozyBushby20144">{{cite journal|last1=Sarkozy|first1=A.|last2=Bushby|first2=K.|last3=Mercuri|first3=E.|title=Muscular Dystrophies|year=2014|doi=10.1016/B978-0-12-801238-3.05597-5}}</ref>
* [[Physical exercise|Low impact exercise]] (eg. [[swimming]]) should be advised. If [[myalgia]] presents, [[Physical exercise|physical activity]] should be reduced and [[myoglobinuria]] cheked out.<ref name="pmid2030129817" />


=== Other Diagnostic Studies[edit | edit source] ===
=== Surgery ===


* [Disease name] may also be diagnosed using [diagnostic study name].
* [[Heart transplantation|Cardiac transplantation]] may be requiered in patients with severe [[Dilated cardiomyopathy classification|dilated cardiomyopathy]].<ref name="pmid2030129817" />
* Findings on [diagnostic study name] include [finding 1], [finding 2], and [finding 3].


The diagnosis of a dystrophinopathy is established in a proband with the characteristic clinical findings and elevated CK concentration and/or by identification of a hemizygous pathogenic variant in ''DMD'' on molecular genetic testing in a male and of a heterozygous pathogenic variant in ''DMD'' on molecular genetic testing in a female. Females may present with a classic dystrophinopathy or may be asymptomatic carriers.
* Severe or incapacitating [[scoliosis]] may be corrected with [[surgery]].<ref name="pmid2030129817" />


=== Primary Prevention ===
There are no primary preventive measures available for Becker's muscular [[dystrophy]].<ref name="urlPathology Outlines - Becker muscular dystrophy" />


A dystrophinopathy should be suspected in any male or female patient presenting with progressive limb-girdle weakness, especially if the patient has a positive family history, substantially elevated CK level, or cardiomyopathy. The diagnosis of DMD should be the physician’s first thought when a 3- to 5- year-old boy who is physically slower than his peers presents with toe walking, large calves, neck weakness, a partial Gower’s sign, and a CK level greater than 3000 U/L. CK levels may be elevated 10- to 200-fold. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT), which are also muscle enzymes, are often elevated. This transaminitis reflects muscle involvement rather than liver disease, and this can be verified by checking the liver-specific transaminase +-glutamyltransferase (GGT), which will be normal. In DMD, DNA analysis of the dystrophin gene is the first diagnostic procedure.
=== Secondary Prevention ===


In patients with BMD or in manifesting female carriers, weakness may not be as pronounced, the CK level may be lower, and the initial procedure will often be electrodiagnostic testing. The EMG reveals myopathic motor units with or without muscle membrane instability. If the patient has no family history of a dystrophinopathy, then a muscle biopsy may be performed. Immunostaining for the N-terminal, rod, and C-terminal regions of dystrophin will usually reveal diffusely decreased, or patchy, staining of some but not all muscle fiber membranes. Confirmatory testing is through DNA analysis. Mutation analysis consists of analysis for duplications and deletions via multiplex PCR or multiplex ligationdependent probe amplification. If this is negative, then gene sequencing is undertaken. Mutations in DMD causative for DMD and BMD are fairly consistent when assessed across different countries,13Y16 with the composition including 43% to 67% deletions and 9% to 11% duplications of exons, 16% to 26% point mutations, and 5% to 6% splice site mutations. Therapies allowing multiexon skipping from exons 45 through 55 would benefit more than 50% of patients with DMD. Mutations disrupting the reading frame (out-of-frame mutations) in DMD create a truncated RNA transcript that is rapidly degraded. This leads to a virtual absence of dystrophin in muscle and a DMD phenotype. Mutations with maintenance of the reading frame (in-frame mutations) generate shorter or less stable dystrophin. Dystrophin with in-frame mutations retain their amino- and carboxy-terminus domains and thus still maintain the mechanical bridge between actin and "-dystroglycan. Inframe mutations more often lead to a BMD phenotype. In a large series, out-of-frame mutations led to a DMD phenotype in nearly 90% of cases; however, in-frame mutations led to a BMD phenotype in only approximately 60% of cases (Case 2-1).13
* Once diagnosed, patients with Becker's muscular [[dystrophy]] are followed-up every year or two years by [[cardiology]]. Follow-up testing includes [[pulmonary function tests]], measurement of [[scoliosis]], wheelchair depence, and [[cardiac assesment]].<ref name="pmid2030129817" />
 
*Annual [[Influenza vaccine|influenza]] and [[Pneumococcal Vaccine 13-Valent|pneumococcal]] vaccines should be given, as well [[vitamin D]] and [[calcium]] to prevent fractures.<ref name="pmid2030129817" />
== Treatment[edit | edit source] ==
 
=== Medical Therapy[edit | edit source] ===
 
* There is no treatment for [disease name]; the mainstay of therapy is supportive care.
 
* The mainstay of therapy for [disease name] is [medical therapy 1] and [medical therapy 2].
* [Medical therapy 1] acts by [mechanism of action 1].
* Response to [medical therapy 1] can be monitored with [test/physical finding/imaging] every [frequency/duration].
 
 
No curative treatment
 
*
*
 
Physical therapy to promote mobility and prevent contractures
 
* Exercise
** All ambulatory boys with DMD or those in early non-ambulatory phase should participate in regular gentle exercise to avoid contractures and disuse atrophy.
** Exercise can consist of a combination of swimming pool and recreation-based activities. Swimming can be continued in non-ambulatory patients under close supervision, if medically safe.
** If patients complain of muscle pain during or after exercise, the activity should be reduced and monitoring for myoglobinuria should be carried out. Myoglobinuria within 24 hours after exercise indicates overexertion leading to rhabdomyolysis.


{{Muscular Dystrophy}}<br />
==References==
<br />
<br />
 
==References== 
=== Surgery[edit | edit source] ===
<nowiki>{{Reflist|2}}</nowiki><br />
 
* Surgery is the mainstay of therapy for [disease name].
* [Surgical procedure] in conjunction with [chemotherapy/radiation] is the most common approach to the treatment of [disease name].
* [Surgical procedure] can only be performed for patients with [disease stage] [disease name].
 
=== Prevention[edit | edit source] ===
 
* There are no primary preventive measures available for [disease name].
 
* Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3].
 
* Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3].
 
Appropriate management of individuals with a dystrophinopathy can prolong survival and improve quality of life.
 
 
''Prevention of secondary complications:'' Evaluation by a pulmonologist and cardiologist before surgeries; pneumococcal and influenza immunizations annually; nutrition assessment; physical therapy to promote mobility and prevent contractures; sunshine and a balanced diet rich in vitamin D and calcium to improve bone density and reduce the risk of fractures; weight control to avoid obesity.
 
 
'''Cardiomyopathy.''' Recommendations are based on an American Academy of Pediatrics policy statement and various additional publications [American Academy of Pediatrics Section on Cardiology and Cardiac Surgery 2005, Jefferies et al 2005, Viollet et al 2012] and apply to patients with the DMD or BMD phenotype.
 
* The authors' institution commonly treats children with DMD or BMD early with an ACE inhibitor and/or beta blocker.
* When used in combination, these appear to lead to initial improvement of left ventricular function; however, ACE inhibitors are also used without beta blockers, with similar results [Viollet et al 2012].
* The optimal time to start treatment in DMD is unknown, but most cardiologists will initiate treatment when the left ventricle ejection fraction drops below 55% and fractional shortening is less than 28% [Jefferies et al 2005, Viollet et al 2012].
* Angiotensin II-receptor blockers (ARBs) such as losartan are similarly effective and can be used in cases of poor tolerability of ACE inhibitors [Allen et al 2013].
* In cases of overt heart failure, other heart failure therapies including diuretics and digoxin are used as needed.
* Cardiac transplantation is offered to persons with severe dilated cardiomyopathy and BMD with limited or no clinical evidence of skeletal muscle disease.
 
'''Scoliosis''' treatment as needed is appropriate. The management of scoliosis involves bracing and surgery. Most patients end up getting a spinal fusion. The use of rods is not contraindicated; therefore, rod and bone grafts are used to fuse the spine. A minority of patients do not develop significant scoliosis and may not require a spinal fusion.
 
'''Corticosteroid therapy.''' Studies have shown that corticosteroids improve the muscle strength and function of individuals with DMD (see Corticosteroid Therapy in DMD). This therapy remains the treatment of choice for affected individuals between ages five and 15 years. Corticosteroid therapy is not recommended in children before age two years [Bushby et al 2010a]. This treatment is also used in BMD, although the efficacy is less clear (see '''BMD''' below).
 
The following published recommendations for corticosteroid therapy are in accordance with the national practice parameters developed by the American Academy of Neurology and the Child Neurology Society [Moxley et al 2005] (full text), as well as the DMD Care Considerations Working Group [Bushby et al 2010a].
 
* Boys with DMD should be offered treatment with prednisone (0.75 mg/kg/day, maximum daily dose: 30-40 mg) or deflazacort (0.9 mg/kg/day, maximum daily dose: 36-39 mg) as soon as plateauing or decline in motor skills is noted, which usually occurs at age 4-8 years. Prior to the initiation of therapy, the potential benefits and risks of corticosteroid treatment should be carefully discussed with each individual.
* To assess benefits of corticosteroid therapy, the following parameters are useful: timed muscle function tests, pulmonary function tests, and age at loss of independent ambulation.
* To assess risks of corticosteroid therapy, maintain awareness of the potential corticosteroid therapy side effects (e.g., weight gain, cushingoid appearance, short stature, decrease in linear growth, acne, excessive hair growth, gastrointestinal symptoms, behavioral changes). There is also an increased frequency of vertebral and long bone fractures with prolonged corticosteroid use [King et al 2007].
* The optimal maintenance dose of prednisone (0.75 mg/kg/day) or deflazacort (0.9 mg/kg/day) should be continued if side effects are not severe. Significant but less robust improvement can be seen with gradual tapering of prednisone to as low as 0.3 mg/kg/day (or ~0.4 mg/kg/day of deflazacort).
* If excessive weight gain occurs (>20% over estimated normal weight for height over a 12-month period), the prednisone dose should be decreased by 25%-33% and reassessed in a few months. If excessive weight gain continues, the dose should be further decreased by an additional 25% to the minimum effective dose cited above after three to four months.
* If significant weight gain or intolerable behavioral side effects occur in patients treated with prednisone, change to deflazacort on a ten-day-on / ten-day-off schedule or a high-dose weekend schedule. In patients on deflazacort, side effects of asymptomatic cataracts and weight gain should be monitored.
 
'''BMD.''' Information about the efficacy of prednisone in treating individuals with BMD is limited. Many clinicians continue treatment with glucocorticoids after loss of ambulation for the purpose of maintaining upper limb strength, delaying the progressive decline of respiratory and cardiac function, and decreasing the risk of scoliosis. Retrospective data suggest that the progression of scoliosis can be reduced by long-term daily corticosteroid treatment; however, an increased risk for vertebral and lower-limb fractures has been documented [King et al 2007]. Men on steroid therapy were less likely to require spinal surgery [Dooley et al 2010b]. The dose is allowed to drift down to 0.3-0.6 mg/kg/day of prednisone or deflazacort, which is still effective [Bushby et al 2010a].
 
== References[edit | edit source] ==
==References==
<nowiki>{{Reflist|2}}</nowiki>
<br />
<br />
{{Muscular Dystrophy}}
[[it:Distrofia muscolare di Becker]]
[[nl:Becker spierdystrofie]]
[[no:Beckers muskeldystrofi]]
[[fi:Beckerin lihasdystrofia]]
{{WikiDoc Help Menu}}
{{WikiDoc Sources}}


[[Category:Disease]]
[[Category:Disease]]

Latest revision as of 17:24, 4 September 2020


WikiDoc Resources for Becker's muscular dystrophy

Articles

Most recent articles on Becker's muscular dystrophy

Most cited articles on Becker's muscular dystrophy

Review articles on Becker's muscular dystrophy

Articles on Becker's muscular dystrophy in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Becker's muscular dystrophy

Images of Becker's muscular dystrophy

Photos of Becker's muscular dystrophy

Podcasts & MP3s on Becker's muscular dystrophy

Videos on Becker's muscular dystrophy

Evidence Based Medicine

Cochrane Collaboration on Becker's muscular dystrophy

Bandolier on Becker's muscular dystrophy

TRIP on Becker's muscular dystrophy

Clinical Trials

Ongoing Trials on Becker's muscular dystrophy at Clinical Trials.gov

Trial results on Becker's muscular dystrophy

Clinical Trials on Becker's muscular dystrophy at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Becker's muscular dystrophy

NICE Guidance on Becker's muscular dystrophy

NHS PRODIGY Guidance

FDA on Becker's muscular dystrophy

CDC on Becker's muscular dystrophy

Books

Books on Becker's muscular dystrophy

News

Becker's muscular dystrophy in the news

Be alerted to news on Becker's muscular dystrophy

News trends on Becker's muscular dystrophy

Commentary

Blogs on Becker's muscular dystrophy

Definitions

Definitions of Becker's muscular dystrophy

Patient Resources / Community

Patient resources on Becker's muscular dystrophy

Discussion groups on Becker's muscular dystrophy

Patient Handouts on Becker's muscular dystrophy

Directions to Hospitals Treating Becker's muscular dystrophy

Risk calculators and risk factors for Becker's muscular dystrophy

Healthcare Provider Resources

Symptoms of Becker's muscular dystrophy

Causes & Risk Factors for Becker's muscular dystrophy

Diagnostic studies for Becker's muscular dystrophy

Treatment of Becker's muscular dystrophy

Continuing Medical Education (CME)

CME Programs on Becker's muscular dystrophy

International

Becker's muscular dystrophy en Espanol

Becker's muscular dystrophy en Francais

Business

Becker's muscular dystrophy in the Marketplace

Patents on Becker's muscular dystrophy

Experimental / Informatics

List of terms related to Becker's muscular dystrophy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Moises Romo, M.D.

Overview

Former "pseudohypertrophic muscular dystrophy", now Becker's muscular dystrophy, is a genetic neuromuscular condition characterized by slowly progresive weakness and atrophy of skeletal (mostly legs and pelvis) and cardiac muscles.

Historical Perspective

Pathophysiology

Clinical Features

Unlike Duchenne muscular dystrophy, Becker's muscular dystrophy (BMD) phenotype presents at a later age, widely variable onset from early childhood to late adulthood, most of them falling in puberty range. Most of the patients will requiere a wheelchair after age 16.[12]

Clinical presentation Becker's muscular dystrophy include:

There is an abcense of fasciculations, and this finding may exclude BMD[13][14]

CNS is rarely afected in Becker's muscular dystrophy, for this reason, intelligence is usually spared.[12][17]

Most of women are asymptomatic carriers, with very rare cases presenting the classic symptoms.[12][9]

Differentiating Becker's muscular dystrophy from other Diseases

Becker's muscular dystrophy must be differentiated from other diseases that cause skelletal and cardiac muscle afection, such as:

Screening


Epidemiology and Demographics

  • The prevalence of Becker's muscular dystrophy is approximately 1-3 per 100,000 individuals.
  • The incidence of Becker's muscular dystrophy is approximately 3-6 per 100,000 male births worldwide.

Age

Becker's muscular dystrophy is diagnosed in 85% of patients by age 25.[21]

Gender

Becker's muscular dystrophy affects mostly men, women are carriers almost exclusively (except rare situation).[22]

Race

  • Becker's muscular dystrophy usually affects individuals of the hispanic race.[23][24]
  • Asian individuals are less likely to develop Becker's muscular dystrophy.[23][24]

Risk Factors

Natural History, Complications and Prognosis


Diagnosis

The diagnosis of Becker's muscular dystrophy is made with a classic clinical presentation plus elevated CK, molecular genetic testing, or muscle biopsy.[33]

Symptoms

Symptoms of Becker's muscular dystrophy may include the following:

Physical Examination

Patients with Becker's muscular dystrophy usually adopt a posture with shoulders held back, abdomen stuck out, and lumbar hyperlordosis.[34]

Physical examination may be remarkable for:

Laboratory Findings

An elevated CK is typical in Becker's muscular dystrophy, with a peak around 10-15 years of age.[35]

Other laboratory findings consistent with Becker's muscular dystrophy may be:

Hystopathology

Histologic findings in Becker's muscular may be:

EMG

EMG in Becker's muscular dystrophy, may reveal myopathic motor units with or without muscle membrane instability.[35][38]

Echocardiography

Echocardiogram should be done at the time of diagnosis.[38][39]

Imaging Findings

There are no X-ray findings characteristic with with Becker's muscular dystrophy, but scoliosis may be found.[34]

Treatment

Medical Therapy

Surgery

Primary Prevention

There are no primary preventive measures available for Becker's muscular dystrophy.[31]

Secondary Prevention

Template:Muscular Dystrophy

References


==References== 

{{Reflist|2}}

  1. ↑ Zeidman LA, Kondziella D (April 2014). "Peter Becker and his Nazi past: the man behind Becker muscular dystrophy and Becker myotonia". J. Child Neurol. 29 (4): 514–9. doi:10.1177/0883073813482773. PMID 23576413.
  2. ↑ "Guillaume Benjamin Amand Duchenne de Boulogne".
  3. ↑ Mercuri E, Bönnemann CG, Muntoni F (November 2019). "Muscular dystrophies". Lancet. 394 (10213): 2025–2038. doi:10.1016/S0140-6736(19)32910-1. PMID 31789220.
  4. ↑ 4.0 4.1 Hoffman, Eric P.; Brown, Robert H.; Kunkel, Louis M. (1987). "Dystrophin: The protein product of the duchenne muscular dystrophy locus". Cell. 51 (6): 919–928. doi:10.1016/0092-8674(87)90579-4. ISSN 0092-8674.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Sarkozy, A.; Bushby, K.; Mercuri, E. (2014). "Muscular Dystrophies". doi:10.1016/B978-0-12-801238-3.05597-5.
  6. ↑ "Becker muscular dystrophy | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program".
  7. ↑ 7.0 7.1 Wicklund MP (December 2013). "The muscular dystrophies". Continuum (Minneap Minn). 19 (6 Muscle Disease): 1535–70. doi:10.1212/01.CON.0000440659.41675.8b. PMID 24305447.
  8. ↑ Iannaccone, Susan T.; Castro, Diana (2013). "Congenital Muscular Dystrophies and Congenital Myopathies". CONTINUUM: Lifelong Learning in Neurology. 19: 1509–1534. doi:10.1212/01.CON.0000440658.03557.f1. ISSN 1080-2371.
  9. ↑ 9.0 9.1 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  10. ↑
  11. ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  12. ↑ 12.0 12.1 12.2 12.3 12.4 12.5 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  13. ↑ 13.0 13.1 13.2 Sarkozy, A.; Bushby, K.; Mercuri, E. (2014). "Muscular Dystrophies". doi:10.1016/B978-0-12-801238-3.05597-5.
  14. ↑ 14.0 14.1 14.2 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  15. ↑ 15.0 15.1 Wicklund MP (December 2013). "The muscular dystrophies". Continuum (Minneap Minn). 19 (6 Muscle Disease): 1535–70. doi:10.1212/01.CON.0000440659.41675.8b. PMID 24305447.
  16. ↑ 16.0 16.1 16.2 16.3 16.4 16.5
  17. ↑ Sarkozy, A.; Bushby, K.; Mercuri, E. (2014). "Muscular Dystrophies". doi:10.1016/B978-0-12-801238-3.05597-5.
  18. ↑ 18.0 18.1 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  19. ↑ 19.0 19.1 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  20. ↑ 20.0 20.1 Deburgrave N, Daoud F, Llense S, Barbot JC, Récan D, Peccate C, Burghes AH, Béroud C, Garcia L, Kaplan JC, Chelly J, Leturcq F (February 2007). "Protein- and mRNA-based phenotype-genotype correlations in DMD/BMD with point mutations and molecular basis for BMD with nonsense and frameshift mutations in the DMD gene". Hum. Mutat. 28 (2): 183–95. doi:10.1002/humu.20422. PMID 17041906.
  21. ↑ Bushby KM, Thambyayah M, Gardner-Medwin D (April 1991). "Prevalence and incidence of Becker muscular dystrophy". Lancet. 337 (8748): 1022–4. doi:10.1016/0140-6736(91)92671-n. PMID 1673177.
  22. ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  23. ↑ 23.0 23.1 "Prevalence of Duchenne / Becker Muscular Dystrophies | CDC".
  24. ↑ 24.0 24.1 "Prevalence of Duchenne/Becker muscular dystrophy among males aged 5-24 years - four states, 2007". MMWR Morb. Mortal. Wkly. Rep. 58 (40): 1119–22. October 2009. PMID 19834452.
  25. ↑ "Prevalence of Duchenne/Becker muscular dystrophy among males aged 5-24 years - four states, 2007". MMWR Morb. Mortal. Wkly. Rep. 58 (40): 1119–22. October 2009. PMID 19834452.
  26. ↑ Barakat-Haddad C, Shin S, Candundo H, Lieshout PV, Martino R (July 2017). "A systematic review of risk factors associated with muscular dystrophies". Neurotoxicology. 61: 55–62. doi:10.1016/j.neuro.2016.03.007. PMID 27018093.
  27. ↑ 27.0 27.1 Emery AE, Skinner R (October 1976). "Clinical studies in benign (Becker type) X-linked muscular dystrophy". Clin. Genet. 10 (4): 189–201. doi:10.1111/j.1399-0004.1976.tb00033.x. PMID 975594.
  28. ↑ 28.0 28.1 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  29. ↑ 29.0 29.1 29.2 29.3 29.4 Passamano L, Taglia A, Palladino A, Viggiano E, D'Ambrosio P, Scutifero M, Rosaria Cecio M, Torre V, DE Luca F, Picillo E, Paciello O, Piluso G, Nigro G, Politano L (October 2012). "Improvement of survival in Duchenne Muscular Dystrophy: retrospective analysis of 835 patients". Acta Myol. 31 (2): 121–5. PMC 3476854. PMID 23097603.
  30. ↑ 30.00 30.01 30.02 30.03 30.04 30.05 30.06 30.07 30.08 30.09 30.10 30.11 "www.mda.org" (PDF).
  31. ↑ 31.0 31.1 31.2 31.3 31.4 "Pathology Outlines - Becker muscular dystrophy".
  32. ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  33. ↑ 33.0 33.1 33.2 33.3 33.4 33.5 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  34. ↑ 34.0 34.1 Smith AD, Koreska J, Moseley CF (August 1989). "Progression of scoliosis in Duchenne muscular dystrophy". J Bone Joint Surg Am. 71 (7): 1066–74. PMID 2760082.
  35. ↑ 35.0 35.1 35.2 Wicklund MP (December 2013). "The muscular dystrophies". Continuum (Minneap Minn). 19 (6 Muscle Disease): 1535–70. doi:10.1212/01.CON.0000440659.41675.8b. PMID 24305447.
  36. ↑ Deburgrave N, Daoud F, Llense S, Barbot JC, Récan D, Peccate C, Burghes AH, Béroud C, Garcia L, Kaplan JC, Chelly J, Leturcq F (February 2007). "Protein- and mRNA-based phenotype-genotype correlations in DMD/BMD with point mutations and molecular basis for BMD with nonsense and frameshift mutations in the DMD gene". Hum. Mutat. 28 (2): 183–95. doi:10.1002/humu.20422. PMID 17041906.
  37. ↑ Lee SH, Lee JH, Lee KA, Choi YC (July 2015). "Clinical and Genetic Characterization of Female Dystrophinopathy". J Clin Neurol. 11 (3): 248–51. doi:10.3988/jcn.2015.11.3.248. PMC 4507379. PMID 26022459.
  38. ↑ 38.0 38.1 Naddaf E, Milone M, Mauermann ML, Mandrekar J, Litchy WJ (2018). "Muscle Biopsy and Electromyography Correlation". Front Neurol. 9: 839. doi:10.3389/fneur.2018.00839. PMC 6189315. PMID 30356714.
  39. ↑ 39.0 39.1 39.2 39.3 39.4 39.5 39.6 Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Darras BT, Urion DK, Ghosh PS. PMID 20301298. Vancouver style error: initials (help); Missing or empty |title= (help)
  40. ↑ 40.0 40.1 Sarkozy, A.; Bushby, K.; Mercuri, E. (2014). "Muscular Dystrophies". doi:10.1016/B978-0-12-801238-3.05597-5.
Retrieved from "https://www.wikidoc.org/index.php?title=Becker%27s_muscular_dystrophy&oldid=1659369"