Hypoplastic Anemias: Fanconi and Diamond–Blackfan

1. What are hypoplastic anemias characterized by?

Hypoplastic anemias are characterized by a significant reduction in hematopoietic cell production, leading to hypocellularity within the bone marrow.

2. Name the two primary classifications of hypoplastic anemias discussed.

The two primary classifications are Fanconi Anemia and Diamond–Blackfan Anemia.

3. What is Fanconi Anemia (FA) defined as?

FA is a hereditary chromosomal instability syndrome defined by progressive bone marrow failure, congenital malformations, and an elevated cancer risk.

4. What is the predominant inheritance pattern for Fanconi Anemia?

Fanconi Anemia is predominantly inherited in an autosomal recessive pattern, though a rare X-linked form exists.

5. Which specific gene is associated with the rare X-linked form of Fanconi Anemia?

The rare X-linked form of Fanconi Anemia specifically involves the FANCB gene.

6. What is the crucial pathogenic mechanism behind Fanconi Anemia?

The pathogenic mechanism involves a defect in DNA interstrand cross-link repair, leading to increased chromosomal breaks and genomic instability.

7. What is the consequence of genomic instability in Fanconi Anemia?

Genomic instability results in the apoptosis, or programmed cell death, of hematopoietic stem cells, causing progressive failure across blood cell lineages.

8. Which blood cell lineages are progressively affected in Fanconi Anemia?

Fanconi Anemia causes progressive failure across the erythroid, myeloid, and megakaryocytic lineages.

9. Name three common congenital anomalies seen in patients with Fanconi Anemia.

Common congenital anomalies include short stature, characteristic café-au-lait spots, thumb and radial ray defects, renal malformations, and microcephaly.

10. What type of cancer predisposition do individuals with Fanconi Anemia have?

They have a high cancer predisposition, particularly to acute myeloid leukemia, myelodysplastic syndrome, and squamous cell carcinomas.

11. What is the key diagnostic test for Fanconi Anemia?

The key diagnostic test for Fanconi Anemia is the chromosomal breakage test, which reveals increased breaks after exposure to agents like DEB or mitomycin C.

12. What would a complete blood count (CBC) typically show in a Fanconi Anemia patient?

A complete blood count would typically show pancytopenia, indicating a reduction in all three major blood cell types.

13. What is Diamond–Blackfan Anemia (DBA) classified as?

Diamond–Blackfan Anemia is classified as a congenital pure red cell aplasia.

14. When does Diamond–Blackfan Anemia typically present?

Diamond–Blackfan Anemia typically presents in infancy.

15. What is the primary inheritance pattern for Diamond–Blackfan Anemia?

Diamond–Blackfan Anemia is mostly inherited in an autosomal dominant manner, though some sporadic cases are also observed.

16. What type of genes are primarily involved in Diamond–Blackfan Anemia?

The genes involved are primarily ribosomal protein genes, with RPS19 being the most common, alongside RPL5, RPL11, and RPS26.

17. What is the pathogenic mechanism in Diamond–Blackfan Anemia?

The pathogenesis involves defective ribosome biogenesis, which impairs erythroid progenitor differentiation, leading to a selective failure of red blood cell production.

18. What are the typical clinical features of Diamond–Blackfan Anemia regarding blood counts?

Clinical features include severe macrocytic anemia and reticulocytopenia, while white blood cell and platelet counts usually remain normal.

19. What does a bone marrow examination reveal in Diamond–Blackfan Anemia?

A bone marrow examination reveals an absence or severe reduction of erythroid precursors.

20. Name two common congenital anomalies associated with Diamond–Blackfan Anemia.

Common congenital anomalies include craniofacial abnormalities, thumb anomalies, short stature, and cardiac defects.

21. What are the main management strategies for Diamond–Blackfan Anemia?

Management includes corticosteroid therapy, regular red blood cell transfusions, iron chelation, and in severe cases, hematopoietic stem cell transplantation.

22. What is the role of molecular genetic testing in diagnosing these anemias?

Molecular genetic testing provides confirmatory evidence for the diagnosis of both Fanconi Anemia and Diamond–Blackfan Anemia.

23. What is a key management strategy for Fanconi Anemia to avoid DNA damage?

A key management strategy for Fanconi Anemia is strict avoidance of DNA-damaging agents, along with regular cancer surveillance.