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'''For patient information, click [[Becker's muscular dystrophy (patient information)|here]]'''
<br />{{SI}}
{{CMG}}; '''Associate Editor(s)-in-Chief:''' [[User:MoisesRomo|Moises Romo, M.D.]]


{{Infobox_Disease
== Overview ==
| Name          = {{PAGENAME}}
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]].
| Image          =  
| Caption        =  
| DiseasesDB    = 1280
| ICD10          = {{ICD10|G|71|0|g|70}}
| ICD9          = {{ICD9|359.1}}
| ICDO          =
| OMIM          =
| MedlinePlus    = 000706
| MeshID        =
}}
{{SI}}
{{CMG}}


==Overview==
== Historical Perspective ==
'''Becker's muscular dystrophy''' (also known as '''''Benign pseudohypertrophic [[muscular dystrophy]]''''') is an [[X-linked recessive]] inherited disorder characterized by slowly progressive muscle weakness of the legs and [[pelvis]].


It is a type of dystrophinopathy, which includes a spectrum of muscle diseases in which there is insufficient dystrophin produced in the muscle cells, resulting in instability in the structure of muscle cell membrane. This is caused by [[mutation]]s in the dystrophin [[gene]], which encodes the [[protein]] [[dystrophin]]. Becker's muscular dystrophy is related to [[Duchenne muscular dystrophy]] in that both result from a mutation in the ''dystrophin'' gene, but in Duchenne muscular dystrophy no functional dystrophin is produced making DMD much more severe than BMD. Both Duchenne and Becker's muscular dystrophy have traditionally been called "X-linked" recessive diseases, but in view of modern molecular biology and identification of the dystrophin gene, it might be more appropriate to say they are X-chromosome recessive diseases.  
* 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 />


==Eponym==
== Pathophysiology ==
Becker's is named after the German doctor Peter Emil Becker. <ref>{{WhoNamedIt|synd|915}}</ref><ref>P. E. Becker, F. Kiener. Eine neue x-chromosomale Muskeldystrophie. Archiv für Psychiatrie und Nervenkrankheiten, Berlin, 1955, 193: 427-448. </ref><ref>P. E. Becker. Neue Ergebnisse der Genetik der Muskeldystrophien. Acta genetica et statistica medica, 1957, 7: 303-310.</ref>


== Genetics ==   
* 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>
* 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 />


[[Image:XlinkRecessive.jpg|left|X-linked recessive inheritance]]
== 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.<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>


The disorder is inherited with an [[X-linked recessive]] inheritance pattern. The gene is located on the X [[chromosome]]. Since women have two X chromosomes, if one X chromosome has the non-working gene, the second X chromosome will have a working copy of the gene to compensate. In these cases, some women have much milder symptoms because of this ability to compensate.  For example, carrier females of mutations are at increased risk for [[dilated cardiomyopathy]].  Since men have an X ''and'' a Y chromosome and because they don't have another X to compensate for the defective gene, they ''will'' develop [[symptom]]s if they inherit the non-working gene.
Clinical presentation Becker's muscular [[dystrophy]] include:


All dystrophinopathes are inherited in an X-linked recessive manner. The risk to the siblings of an affected individual depends upon the carrier status of the mother. Carrier females have a 50% chance of passing the DMD mutation in each [[pregnancy]]. Sons who inherit the mutation will be affected; daughters who inherit the mutation will be carriers. Men who have Becker's muscular dystrophy can have children, and all their daughters are carriers, but none of the sons will inherit their father's mutation. [[Prenatal testing]] through [[amniocentesis]] or [[chorionic villus sampling]] (CVS) for pregnancies at risk is possible if the DMD mutation is found in a family member or if informative linked markers have been identified.
* Progressive symmetric muscle weakness, with a predilection in proximal muscles (eg. pelvic, legs, shoulders)<ref name="pmid203012984" />
*[[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="pmid203012984" /><ref name="pmid17162189" />
*[[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="pmid203012984" /><ref name="pmid17162189" />
* 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>


Becker's muscular dystrophy occurs in approximately 3 to 6 in 100,000 male births. Symptoms usually appear in men at about ages 8-25, but may sometimes begin later. The average age of becoming unable to walk is 25-70. Women rarely develop symptoms.
There is an abcense of fasciculations, and this finding may exclude BMD<ref name="SarkozyBushby20142" /><ref name="pmid203012988" />


[[Genetic counseling]] is indicated for individuals or families who may carry this condition.
[[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>


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


# Muscle weakness, slowly progressive (Difficulty running, hopping, jumping; Progressive difficulty walking)
== Differentiating Becker's muscular dystrophy from other Diseases ==
# Ability to walk may continue into adulthood (up to age 80)
Becker's muscular dystrophy must be differentiated from other diseases that cause skelletal and cardiac muscle afection, such as:
# Frequent falls
# Difficulty [[respiration (physiology)|breathing]]
# Non progressive cognitive dysfunction only in rare cases: not as common as in duchenne because the brain only needs small amounts of dystrophin
# [[Skeleton|Skeletal]] deformities, [[chest]] and [[back]] ([[scoliosis]])
# Muscle deformities (contractions of [[heel]]s, legs; Pseudohypertrophy of [[calf muscle]]s)
# [[Fatigue (physical)|Fatigue]]
# [[Heart disease]]


People with this disorder typically experience progressive muscle weakness of the leg and pelvis muscles, which is associated with a loss of muscle mass ([[wasting]]). Muscle weakness also occurs in the arms, neck, and other areas, but not as noticeably severe as in the lower half of the body.
* [[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]].
* [[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="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]].
* [[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 />


Calf muscles initially enlarge during the ages of 5-15 (an attempt by the body to compensate for loss of muscle strength), but the enlarged muscle tissue is eventually replaced by [[fat]] and [[connective tissue]] (pseudohypertrophy) as the legs become less used (use of wheelchair).
== Screening ==


Muscle contractions occur in the legs and heels, causing inability to use the muscles because of shortening of muscle fibers and [[fibrosis]] of connective tissue. [[Bone]]s may develop abnormally, causing skeletal deformities of the chest and other areas.
* [[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.<ref name="pmid17041906" /><ref name="pmid2030129811" />


[[Cardiomyopathy]] (damage to the heart) does not occur as commonly with this disorder as it does with Duchenne's muscular dystrophy. Cognitive problems may accompany the disorder, but they are not inevitable and do not worsen as the disorder progresses.
<br />


==Signs and tests ==
== Epidemiology and Demographics ==


The pattern of symptom development resembles that of [[Duchenne's muscular dystrophy]], but with a later, and much slower rate of progression. Noticeable signs of Muscular Dystrophy also include the lack of pectroral and upper arm muscles, especially when the disease is unnoticed through the early teen years. Muscle wasting begins in the legs and pelvis (or core), then progresses to the muscles of the shoulders and neck, followed by loss of arm muscles and respiratory muscles. Calf muscle enlargement (pseudohypertrophy) is quite obvious. Cardiomyopathy may occur, but the development of [[congestive heart failure]] or [[arrhythmia]]s (irregular heartbeats) is rare.
* 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.


* The ability to walk may continue to age 40 or older.
=== Age ===
* [[Creatine kinase]] (CPK) levels may be elevated.
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>
* An [[electromyography]] (EMG) shows that weakness is caused by destruction of muscle tissue rather than by damage to [[nerve]]s.
* [[Genetic testing]]
*A muscle [[biopsy]] ([[immunohistochemistry]] or [[immunoblotting]]) or genetic test ([[blood test]]) confirms the [[diagnosis]].


==Treatment ==
=== Gender ===
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>


There is no known cure for Becker's muscular dystrophy. Treatment is aimed at control of symptoms to maximize the quality of life.
=== Race ===


Activity is encouraged. Inactivity (such as [[bed rest]]) can worsen the muscle disease. [[Physical therapy]] may be helpful to maintain muscle strength. [[Orthopedic]] appliances such as braces and [[wheelchair]]s may improve mobility and self-care.
* 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" />


Genetic counseling may be advisable. Sons of a man with Becker's muscular dystrophy do not develop the disorder, but daughters will be carriers. The daughters' sons may develop the disorder.
== Risk Factors ==


Immunosuppressant steroids like Prednisone have been known to help slow the progression of Becker Muscular Dystrophy. The drug contributes to an increased production of the protein Utrophin which closely resembles Dystrophin, the protein that is defective in BMD.
* 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>
* 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 ==


===MY0-029===
* 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>
{{Main|Stamulumab}}
* 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>
MYO-029 is an experimental [[myostatin]] inhibiting drug developed by [[Wyeth|Wyeth Pharmaceuticals]] for the treatment of muscular dystrophy. [[Myostatin]] is a protein that inhibits the growth of muscle tissue, MYO-029 is a recombinant human antibody designed to bind and inhibit the activity of [[myostatin]].  
* 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>


A 2005/2006 study, which included participants afflicted with Becker's, was completed by Wyeth in Collegeville, PA.
<br />


==Prognosis ==  
== Diagnosis ==
Becker's muscular dystrophy results in slowly progressive disability. Death can occur in the fifth decade but some patients live to an advanced age of 68 or later.
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" />


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


* Deformities
* [[Anatomical terms of location|Proximal]] [[muscle weakness]]<ref name="urlwww.mda.org" /><ref name="pmid23097603" />
* Permanent, progressive disability manifested as decreased mobility or decreased ability to care for self
* [[Myalgia|Myalgias]]<ref name="urlwww.mda.org" /><ref name="pmid2030129816" />
* [[Mental illness|Mental impairment]]
* [[Cramp|Muscle cramps]]<ref name="urlwww.mda.org" />
* [[Cardiomyopathy]]
* [[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>
** [[Noncompaction Cardiomyopathy]]
* [[Toe walking]]<ref name="pmid23097603" />
* [[Pneumonia]] or other respiratory infections
* Difficulty raising from a chair<ref name="urlwww.mda.org" /><ref name="pmid23097603" /><ref name="pmid2030129816" />
* [[Respiratory failure]]
* 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" />


==Quality of Life==
=== Physical Examination ===
The quality of life for patients with Becker's muscular dystrophy need not be impacted by the symptoms of the disorder. With assistive devices, independence can be maintained indefinitely. People affected by Becker's muscular dystrophy can still drive, work, own businesses, and maintain active lifestyles. Those affected by the disorder can also still participate in sports for the disabled, such as wheelchair tennis or Power Soccer.
Patients with Becker's muscular dystrophy usually adopt a posture with shoulders held back, abdomen stuck out, and lumbar hyperlordosis.<ref name="pmid2760082" />


==References==
Physical examination may be remarkable for:
{{reflist|2}}
 
*Calf [[Hypertrophy (medical)|hypertrophy]]<ref name="urlwww.mda.org" />
*[[Gowers sign]]<ref name="urlwww.mda.org" />
*[[Cardiac arrhythmia|Arrythmias]]<ref name="urlwww.mda.org" />
 
=== 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" />
 
Other laboratory findings consistent with Becker's muscular dystrophy may be:
 
* 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>
* [[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>
* 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>
 
=== Hystopathology ===
[[Histological section|Histologic]] findings in Becker's muscular may be:
 
* [[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" />
 
=== EMG ===
[[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>
 
=== Echocardiography ===
[[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>
 
=== 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 />
== Treatment ==
 
=== Medical Therapy ===
 
* 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" />
* [[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" />
* 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" />
 
=== Surgery ===
 
* [[Heart transplantation|Cardiac transplantation]] may be requiered in patients with severe [[Dilated cardiomyopathy classification|dilated cardiomyopathy]].<ref name="pmid2030129817" />
 
* 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" />


{{CDC}}
=== Secondary Prevention ===


{{Muscular Dystrophy}}
* 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" />
[[it:Distrofia muscolare di Becker]]
*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" />
[[nl:Becker spierdystrofie]]
[[no:Beckers muskeldystrofi]]
[[fi:Beckerin lihasdystrofia]]


{{WikiDoc Help Menu}}
{{Muscular Dystrophy}}<br />
{{WikiDoc Sources}}
==References==
<br />
==References== 
<nowiki>{{Reflist|2}}</nowiki><br />
<br />


[[Category:Disease]]
[[Category:Disease]]
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[[Category:Muscular dystrophy]]
[[Category:Muscular dystrophy]]
[[Category:Genetic disorders]]
[[Category:Genetic disorders]]
<references />

Latest revision as of 17:24, 4 September 2020


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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.
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