Practice questions answers Anemia III

Practice Questions Answers

Anemia III

© Jun Wang, MD, PhD

 

Abbreviations:

Hb: hemoglobin	HCT: hematocrit
MCV: Mean Corpuscular Volume	MCH: Mean Corpuscular Hemoglobin
RDW: Red Cell Distribution Width	TIBC: total iron binding capacity

 

1. D. Presence of sickle cell or target cells is suggestive of hemoglobin abnormalities. Hemoglobin electrophoresis is very helpful in diagnosing hemoglobin abnormalities, including thalassemia, sickle cell anemia, HbC and HbE. Chromosomal breakage tests and molecular tests for FANC gene mutations are used to diagnose Fanconi anemia. Enzymatic activity of G6PD is used to diagnose G6PD deficiency. Eosin-5-maleimide binding assay and osmotic fragility test is used to diagnose hereditary spherocytosis.

2. B. Equally increased HbE and HbS is seen HbSE disease, caused by glutamate to lysine substitution at codon 26 of 1 b gene, and glutamate to valine substitution at codon 6 of the other b gene glutamate (HbE and HbS, respectively). Glutamate to lysine substitution at codon 26 of 1 or 2 beta globin is seen in heterozygous or homozygous HbE, respectively. Glutamate to valine substitution at codon 6 of 1 or both beta globin is seen in sickle cell trait, or sickle cell anemia respectively.

3. D. See discussion of question 2. HbC disease is characterized by presence of rhomboidal crystals in peripheral blood smear and HbC in electrophoresis. HbE disease is characterized by presence of target cells in peripheral blood smear and HbE in electrophoresis. Beta thalassemia minor usually do not have anemia, and no Hb Bart, HbH, HbC, HbE, nor HbS should be detected by electrophoresis. Sickle cell and HbS will be present if sickle cell mutation is present. 

4. D. See discussion of question 1.

5. B. This patient has low-normal hemoglobin but has low MCV and MCH. Peripheral smear presence of target cells and the normal Hb electrophoresis pattern is suggestive of a mild form of hemoglobin abnormality, such as alpha thalassemia carrier or trait, or beta thalassemia minor. Molecular studies of both alpha and beta genes are needed for diagnosis confirmation. Also see discussion of question 1.

6. A. This patient has normal hemoglobin electrophoresis pattern, more consistent with alpha thalassemia carrier, caused by deletion of 1 alpha globin gene. Alpha thalassemia trait has mildly decreased HbA, and deletion of 2 alpha globin genes, and may have Hb Bart at birth. Both alpha thalassemia carrier or trait have normal Hb electrophoresis pattern. Deletion of 1 beta globin can be seen in beta thalassemia minor or intermedia. Hb electrophoresis of beta thalassemia minor or intermedia have elevated Hb A2 and HbF. Also see discussion of question 2.  

7. A. See discussion of questions 2 and 6. Beta thalassemia major is associated with markedly reduction of beta globin chains, likely due to abnormalities of both beta globin genes. HbH is caused by deletion of 3 alpha globin genes.

8. B. This patient has mild microcytic anemia with increased RBC count. Hemoglobin electrophoresis is normal, suggesting of alpha thalassemia trait or beta thalassemia minor. DNA analysis for gene copy numbers is needed for diagnosis of alpha thalassemia trait and molecular test for relevant genetic abnormalities is need for diagnosis of beta thalassemia. Also see discussion of question 1.

9. B. See discussion of questions 2 and 6.

10. A. See discussion of questions 2 and 6. Hemolytic anemia has elevated LDH and bilirubin. Iron deficiency anemia has abnormal iron study results. Sickle cell trait has HbS.

11. D. This patient has microcytic anemia and target cells, suggestive of hemoglobin abnormalities. Also see discussion of question 1.

12. B. See discussion of questions 1 and 8.

13. C. See discussion of questions 6 and 7. Deletion of 4 alpha globin genes causes Hb Bart disease, usually has more than 30% Hb Bart per electrophoresis.

14. D. See discussion of questions 6, 7 and 13.

15. C. This case is characterized by fetal hydrops changes. The mother has no sign of anemia while the father has microcytic anemia. Both of the parents have normal hemoglobin electrophoresis results, suggesting that both parents might be alpha thalassemia trait or beta thalassemia minor, and hydrops fetalis due to Hb Bart may occur when the fetus has all mutated globin genes. DNA analysis for gene copy numbers is needed for diagnosis of alpha thalassemia trait and molecular test for relevant genetic abnormalities is need for diagnosis of beta thalassemia. Maternal anti-D may cause hemolytic disease of fetus, but commonly not affecting first pregnancy. Direct antiglobulin test can identify antibodies/complement bound directly to RBCs. It would be positive for immune hemolytic anemia. IgM does not pass placenta and should not cause damages of fetus.

16.  B. Since both parents have cis deletion of 2 alpha globin genes, the fetus has 25% chance of acquired both defected chromosome and have Hb Bart disease. Tissue anoxia is resulted due to absence of normal hemoglobin in fetus with Hb Bart disease. Other conditions do not have proper supportive clinical findings or laboratory results.

17. C. See discussion of question 16.

18. D. See discussion of question 1.

19. C. This case is characterized by mild anemia with increased RBC count, compatible with alpha thalassemia trait or beta thalassemia minor. Genetic testing did not find deletion of any alpha genes, making alpha thalassemia trait unlikely. Beta thalassemia intermediate or major has lower Hb levels of 7-10 and less than 7 g/dL, respectively.

20. C. This case is characterized by early onset of microcytic anemia, unique facial features, presence of targe cells in peripheral blood, and family history of anemia, highly suggestive of hemoglobin abnormalities, especially beta thalassemia. See discussion of question 1. Hepatitis and renal failuure may cause anemia of chronic disease, that usually is normocytic anemia. 

21. C. The facial changes in patients with beta thalassemia is associated with bone expansion, resulted from hematopoietic hyperplasia. Other conditions do not have proper supportive clinical findings or laboratory results.

22. C. This is a patient with severe anemia and facial features supportive of the diagnosis of beta thalassemia major, when electrophoresis shows predominately HbF and absence of minimal HbA. HbSS has predominantly HbS. Equally increased HbC and HbS is seen HbC disease, characterized by presence of rhomboidal crystals. Markedly elevated HbF is seen in new born or beta thalassemia major. Equal amounts of HbA and HbC is seen in patients with heterozygous HbC mutation. Slightly increased HbF can be seen in Beta thalassemia trait. Predominantly HbA with small amounts of HbA2 and HbF is seen in normal populations.

23. E. See discussion of questions 19 and 22.

 

 

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