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Diamond Blackfan Anemia (DBA)
Diamond Blackfan Anemia (DBA) is an inherited bone marrow failure syndrome characterized by a failure in red blood cell production. Individuals with DBA typically have low red blood cell counts with normal platelet and white blood cell counts.
What are the major findings on physical examination
- Short stature
- Abnormal thumbs (~25% of individuals with DBA)
- Kidney abnormalities (~20% of individuals with DBA)
- Microcephaly (small head)
- Cleft lip/palate
What is the age at diagnosis?
- Anytime from birth to more than 60 years of age
- 90% of individuals are younger than 1 year old when the diagnosis is made
What is the natural progression of bone marrow failure in individuals with DBA?
- Some individuals with DBA live for years without bone marrow failure while others develop symptoms earlier.
What types of cancer are individuals with DBA at higher risk of developing?
- Leukemia (cancer of the blood and bone marrow)
- Osteosarcoma (cancer of the bone)
- Colon cancer
How is DBA specifically diagnosed?
- Red blood cells are abnormally large
- Increase in a specific red cell enzyme called adenosine deaminase (ADA)
- Genetic testing
Genetics
- DBA is a ribosome biology disorder, and most known abnormal gene variants are in genes of the ribosome pathway.
- Detecting a genetic variant in a known DBA gene confirms the diagnosis. Failure to identify a an abnormal DBA gene does not exclude the diagnosis of DBA, since only about 70% of DBA individuals have an identified DBA gene.
- There are 21 genes known to cause DBA
- 6 most common genes are found in about 90% of people with DBA and a known gene: RPL5, RPL11, RPL26, RPL35a, RPS19, RPS24
- Other genes: RPL5, RPL11, RPL15, RPL18, RPL26, RPL2, RPL31, RPL35, RPL35A, RPS7, RPS10, RPS17, RPS19, RPS24, RPS26, RPS27, RPS28, RPS29, RPS15A, TSR2 ,GATA1
- About 30% of individuals do not have abnormal genetic variants in the known genes, and more genes await discovery.
The disease is usually inherited in an autosomal dominant fashion. This means that individuals only need one copy of the gene variant to have DBA. Less than half are inherited from a parent, while the majority are new genetic variants (de novo) in the affected individuals.