Diamond-Blackfan anemia pathophysiology: Difference between revisions

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==Pathophysiology==
==Pathophysiology==


*Diamond Blackfan anemia is characterized by a block in erythropoiesis which is due to the ribosomal protein gene mutation in about 80-85% of those affected.DBA is most frequently due to a sporadic mutation (55%) in genes encoding several different ribosomal proteins, although based on the latest studies, approximately 40 – 45% of DBA cases are hereditary which are inherited with autosomal dominant inheritance which means that a single copy of an altered gene in each cell is adequate to cause the disorder.<ref name="pmid22160079">{{cite journal |vauthors=Ball S |title=Diamond Blackfan anemia |journal=Hematology Am Soc Hematol Educ Program |volume=2011 |issue= |pages=487–91 |date=2011 |pmid=22160079 |doi=10.1182/asheducation-2011.1.487 |url=}}</ref><ref name="pmid23744582">{{cite journal |vauthors=Garçon L, Ge J, Manjunath SH, Mills JA, Apicella M, Parikh S, Sullivan LM, Podsakoff GM, Gadue P, French DL, Mason PJ, Bessler M, Weiss MJ |title=Ribosomal and hematopoietic defects in induced pluripotent stem cells derived from Diamond Blackfan anemia patients |journal=Blood |volume=122 |issue=6 |pages=912–21 |date=August 2013 |pmid=23744582 |pmc=3739037 |doi=10.1182/blood-2013-01-478321 |url=}}</ref> and they have a family history of the disease with varying phenotypes.<ref name="pmid30228860">{{cite journal |vauthors=Da Costa L, Narla A, Mohandas N |title=An update on the pathogenesis and diagnosis of Diamond-Blackfan anemia |journal=F1000Res |volume=7 |issue= |pages= |date=2018 |pmid=30228860 |pmc=6117846 |doi=10.12688/f1000research.15542.1 |url=}}</ref> about 25% of patients have mutations in the [[ribosomal|ribosome]] protein S19 (RPS19) gene on chromosome 19 at [[cytogenetic]] position 19q13.2 which is responsible for a defect in rRNA maturation. However, the disease characterized by genetic [[heterogeneity]] and other mutated genes also been found in RPL5, RPL11, RPL35A, RPS7, RPS10, RPS17, RPS24, and RPS26, and rarely in RPL15, RPL17, RPL19, RPL26, RPL27, RPL31, RPS15A, RPS20, RPS27, RPS28, RPS29, and "non-RP" genes such as TSR2 and GATA1. TSR2 playS a role in ribosome biogenesis since it is involved in the pre-rRNA processing and binds to RPS26 and GATA1 which is the major erythroid transcription factor and plays a critical role in regulating normal erythroid differentiation by activating an array of erythroid genes. In the remaining 10-15% of DBA cases, no abnormal genes have yet been identified.  
*Diamond Blackfan anemia is characterized by a block in erythropoiesis which is due to the ribosomal protein gene mutation in about 80-85% of those affected.DBA is most frequently due to a sporadic mutation (55%) in genes encoding several different ribosomal proteins, although based on the latest studies, approximately 40 – 45% of DBA cases are hereditary which are inherited with autosomal dominant inheritance which means that a single copy of an altered gene in each cell is adequate to cause the disorder.<ref name="pmid22160079">{{cite journal |vauthors=Ball S |title=Diamond Blackfan anemia |journal=Hematology Am Soc Hematol Educ Program |volume=2011 |issue= |pages=487–91 |date=2011 |pmid=22160079 |doi=10.1182/asheducation-2011.1.487 |url=}}</ref><ref name="pmid23744582">{{cite journal |vauthors=Garçon L, Ge J, Manjunath SH, Mills JA, Apicella M, Parikh S, Sullivan LM, Podsakoff GM, Gadue P, French DL, Mason PJ, Bessler M, Weiss MJ |title=Ribosomal and hematopoietic defects in induced pluripotent stem cells derived from Diamond Blackfan anemia patients |journal=Blood |volume=122 |issue=6 |pages=912–21 |date=August 2013 |pmid=23744582 |pmc=3739037 |doi=10.1182/blood-2013-01-478321 |url=}}</ref> and they have a family history of the disease with varying phenotypes.<ref name="pmid30228860">{{cite journal |vauthors=Da Costa L, Narla A, Mohandas N |title=An update on the pathogenesis and diagnosis of Diamond-Blackfan anemia |journal=F1000Res |volume=7 |issue= |pages= |date=2018 |pmid=30228860 |pmc=6117846 |doi=10.12688/f1000research.15542.1 |url=}}</ref> about 25% of patients have mutations in the [[ribosomal|ribosome]] protein S19 (RPS19) gene on chromosome 19 at [[cytogenetic]] position 19q13.2 which is responsible for a defect in rRNA maturation. However, the disease characterized by genetic [[heterogeneity]] and other mutated genes also been found in RPL5, RPL11, RPL35A, RPS7, RPS10, RPS17, RPS24, and RPS26, and rarely in RPL15, RPL17, RPL19, RPL26, RPL27, RPL31, RPS15A, RPS20, RPS27, RPS28, RPS29, and "non-RP" genes such as TSR2 and GATA1. TSR2 playS a role in ribosome biogenesis since it is involved in the pre-rRNA processing and binds to RPS26 and GATA1 which is the major erythroid transcription factor and plays a critical role in regulating normal erythroid differentiation by activating an array of erythroid genes. In the remaining 10-15% of DBA cases, no abnormal genes have yet been identified. It is likely that mutations are in a regulatory region including intronic regions and promoters in one of the known RP genes may account for the DBA phenotype. <ref name="pmid30228860">{{cite journal |vauthors=Da Costa L, Narla A, Mohandas N |title=An update on the pathogenesis and diagnosis of Diamond-Blackfan anemia |journal=F1000Res |volume=7 |issue= |pages= |date=2018 |pmid=30228860 |pmc=6117846 |doi=10.12688/f1000research.15542.1 |url=}}</ref>


*Mutations in RP genes have been confirmed to be the direct cause of faulty erythropoiesis and anemia, and are found in more than half of DBA cases. <ref name="pmid23463023">{{cite journal |vauthors=Vlachos A, Dahl N, Dianzani I, Lipton JM |title=Clinical utility gene card for: Diamond-Blackfan anemia--update 2013 |journal=Eur. J. Hum. Genet. |volume=21 |issue=10 |pages= |date=October 2013 |pmid=23463023 |pmc=3778360 |doi=10.1038/ejhg.2013.34 |url=}}</ref>.A generally documented pathogenetic hypothesis implies that a defective ribosome biosynthesis leads to apoptosis in erythroid progenitors which in turn is leading to erythroid failure. This mechanism has been named ‘‘ribosomal stress . in ‘‘ribosomal stress,  reduced RP synthesis activates p53 that induces the downstream events and leads to cell cycle termination or apoptosis. Finally, this phenomenon results in the DBA phenotype of anemia, deprived growth and results in congenital abnormalities. Mutated RP genes in DBA encode ribosomal proteins which are involved in either the small (RPS) or large (RPL) subunits of these proteins and the scarcity of these proteins can cause the development of the disease.<ref name="pmid19327583">{{cite journal |vauthors=Lipton JM, Ellis SR |title=Diamond-Blackfan anemia: diagnosis, treatment, and molecular pathogenesis |journal=Hematol. Oncol. Clin. North Am. |volume=23 |issue=2 |pages=261–82 |date=April 2009 |pmid=19327583 |pmc=2886591 |doi=10.1016/j.hoc.2009.01.004 |url=}}</ref> <ref name="pmid19327583">{{cite journal |vauthors=Lipton JM, Ellis SR |title=Diamond-Blackfan anemia: diagnosis, treatment, and molecular pathogenesis |journal=Hematol. Oncol. Clin. North Am. |volume=23 |issue=2 |pages=261–82 |date=April 2009 |pmid=19327583 |pmc=2886591 |doi=10.1016/j.hoc.2009.01.004 |url=}}</ref>
*Mutations in RP genes have been confirmed to be the direct cause of faulty erythropoiesis and anemia.<ref name="pmid23463023">{{cite journal |vauthors=Vlachos A, Dahl N, Dianzani I, Lipton JM |title=Clinical utility gene card for: Diamond-Blackfan anemia--update 2013 |journal=Eur. J. Hum. Genet. |volume=21 |issue=10 |pages= |date=October 2013 |pmid=23463023 |pmc=3778360 |doi=10.1038/ejhg.2013.34 |url=}}</ref>.A generally documented pathogenetic hypothesis implies that a defective ribosome biosynthesis leads to apoptosis in erythroid progenitors which in turn is leading to erythroid failure. This mechanism has been named ‘‘ribosomal stress . in ‘‘ribosomal stress,  reduced RP synthesis activates p53 that induces the downstream events and leads to cell cycle termination or apoptosis. Finally, this phenomenon results in the DBA phenotype of anemia, deprived growth, and results in congenital abnormalities. Mutated RP genes in DBA encode ribosomal proteins which are involved in either the small (RPS) or large (RPL) subunits of these proteins and the scarcity of these proteins can cause the development of the disease.<ref name="pmid19327583">{{cite journal |vauthors=Lipton JM, Ellis SR |title=Diamond-Blackfan anemia: diagnosis, treatment, and molecular pathogenesis |journal=Hematol. Oncol. Clin. North Am. |volume=23 |issue=2 |pages=261–82 |date=April 2009 |pmid=19327583 |pmc=2886591 |doi=10.1016/j.hoc.2009.01.004 |url=}}</ref>
 
 
===Genetics===
 
Approximately 10-25% of DBA cases have a family history of disease, and most [[pedigrees]] suggest an [[autosomal dominant]] mode of inheritance.  The disease is characterized by genetic [[heterogeneity]], with current evidence supporting the existence of at least three [[genes]] mutated in DBA.  In 1997, a patient was identified who carried a rare balanced [[chromosomal translocation]] involving [[chromosome]] 19 and the X chromosome.  This suggested that the affected gene might lie in one of the two regions that were disrupted by this [[cytogenetic]] [[anomaly]].  [[Genetic linkage|Linkage]] analysis in affected families also implicated this region in disease, and led to the cloning of the first DBA gene.  About 20-25% of DBA cases are caused by mutations in the [[ribosomal|ribosome]] protein S19 (RPS19) gene on chromosome 19 at [[cytogenetic]] position 19q13.2.  Interestingly, some previously undiagnosed relatives of DBA patients were found to carry mutations.  These patients also had increased adenosine deaminase levels in their red blood cells but no other overt signs of disease.  A subsequent study of families with no evidence of RPS19 mutations determined that 18 of 38 families showed evidence for involvement of an unknown gene on chromosome 8 at 8p23.3-8p22.  The precise genetic defect in these families has not yet been delineated.  In a further 7 families, both the chromosome 19 and chromosome 8 loci could be excluded for involvement, suggesting the existence of at least one other DBA [[locus (genetics)|locus]] in the [[human genome]].
 
===Molecular Basis===
 
The phenotype of DBA patients suggests a [[hematology|hematological]] [[stem cell]] defect specifically affecting the erythroid progenitor population.  This is difficult to reconcile with the known function of the single known DBA gene.  The RPS19 protein is involved in the production of [[ribosomes]].  As such, loss of RPS19 function would be predicted to affect [[translation (genetics)|translation]] and [[protein biosynthesis]] and have a much broader impact.  Disease features may be related to the nature of RPS19 [[mutations]].  The disease is characterized by dominant inheritance, and therefore arises due to a partial loss of RPS19 protein function.  It is possible that erythroid progenitors are acutely sensitized to this decreased function, while most other tissues are unaffected.


==References==
==References==

Revision as of 20:28, 4 August 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Pathophysiology

  • Diamond Blackfan anemia is characterized by a block in erythropoiesis which is due to the ribosomal protein gene mutation in about 80-85% of those affected.DBA is most frequently due to a sporadic mutation (55%) in genes encoding several different ribosomal proteins, although based on the latest studies, approximately 40 – 45% of DBA cases are hereditary which are inherited with autosomal dominant inheritance which means that a single copy of an altered gene in each cell is adequate to cause the disorder.[1][2] and they have a family history of the disease with varying phenotypes.[3] about 25% of patients have mutations in the ribosome protein S19 (RPS19) gene on chromosome 19 at cytogenetic position 19q13.2 which is responsible for a defect in rRNA maturation. However, the disease characterized by genetic heterogeneity and other mutated genes also been found in RPL5, RPL11, RPL35A, RPS7, RPS10, RPS17, RPS24, and RPS26, and rarely in RPL15, RPL17, RPL19, RPL26, RPL27, RPL31, RPS15A, RPS20, RPS27, RPS28, RPS29, and "non-RP" genes such as TSR2 and GATA1. TSR2 playS a role in ribosome biogenesis since it is involved in the pre-rRNA processing and binds to RPS26 and GATA1 which is the major erythroid transcription factor and plays a critical role in regulating normal erythroid differentiation by activating an array of erythroid genes. In the remaining 10-15% of DBA cases, no abnormal genes have yet been identified. It is likely that mutations are in a regulatory region including intronic regions and promoters in one of the known RP genes may account for the DBA phenotype. [3]
  • Mutations in RP genes have been confirmed to be the direct cause of faulty erythropoiesis and anemia.[4].A generally documented pathogenetic hypothesis implies that a defective ribosome biosynthesis leads to apoptosis in erythroid progenitors which in turn is leading to erythroid failure. This mechanism has been named ‘‘ribosomal stress . in ‘‘ribosomal stress, reduced RP synthesis activates p53 that induces the downstream events and leads to cell cycle termination or apoptosis. Finally, this phenomenon results in the DBA phenotype of anemia, deprived growth, and results in congenital abnormalities. Mutated RP genes in DBA encode ribosomal proteins which are involved in either the small (RPS) or large (RPL) subunits of these proteins and the scarcity of these proteins can cause the development of the disease.[5]

References

  1. Ball S (2011). "Diamond Blackfan anemia". Hematology Am Soc Hematol Educ Program. 2011: 487–91. doi:10.1182/asheducation-2011.1.487. PMID 22160079.
  2. Garçon L, Ge J, Manjunath SH, Mills JA, Apicella M, Parikh S, Sullivan LM, Podsakoff GM, Gadue P, French DL, Mason PJ, Bessler M, Weiss MJ (August 2013). "Ribosomal and hematopoietic defects in induced pluripotent stem cells derived from Diamond Blackfan anemia patients". Blood. 122 (6): 912–21. doi:10.1182/blood-2013-01-478321. PMC 3739037. PMID 23744582.
  3. 3.0 3.1 Da Costa L, Narla A, Mohandas N (2018). "An update on the pathogenesis and diagnosis of Diamond-Blackfan anemia". F1000Res. 7. doi:10.12688/f1000research.15542.1. PMC 6117846. PMID 30228860.
  4. Vlachos A, Dahl N, Dianzani I, Lipton JM (October 2013). "Clinical utility gene card for: Diamond-Blackfan anemia--update 2013". Eur. J. Hum. Genet. 21 (10). doi:10.1038/ejhg.2013.34. PMC 3778360. PMID 23463023.
  5. Lipton JM, Ellis SR (April 2009). "Diamond-Blackfan anemia: diagnosis, treatment, and molecular pathogenesis". Hematol. Oncol. Clin. North Am. 23 (2): 261–82. doi:10.1016/j.hoc.2009.01.004. PMC 2886591. PMID 19327583.