CLINICAL CASES
117
C O M P R E H E N SIO N Q U E ST IO N S
Micawley Talltwin is a 7-year-old child star who is brought to his pediatrician
by his parents after they noticed that he felt very fatigued. They also noted that
his abdomen seemed to be enlarged. Examination reveals an enlarged spleen.
Further history reveals that he has been taking vitamins and iron supplements
over the last few months. Laboratory tests show a microcytic anemia and ele-
vated iron levels in tissues.
[12.1] Which of the following conditions is most consistent with the findings
in this patient?
A. Aplastic anemia
B. Cooley anemia
C. Pernicious anemia
D. Thalassemia major
E. Thalassemia minor
[12.2] After diagnosing Micawley Talltwin and ascertaining he is not agranu-
locytic, his physician prescribes subcutaneous infusion of deferroxam-
ine, an iron chelator, and monitors him for several weeks. What is his
condition most likely to be on reexamination?
A. Iron levels decrease, but he remains anemic.
B. Iron levels decrease, and anemia recovers.
C. He develops irreversible and severe agranulocytosis.
D. Iron and vitamin C levels decrease.
[12.3] An electrophoretic analysis of Micawley Talltwin’s hemoglobin indi-
cates that although there is a decrease in the relative amount of the
P-chain with respect to the a-chain, both the P- and the a-chains
migrate at the same position as normal chains. Most likely his anemia
is caused by which of the following?
A. A defect in an enzyme involved in heme synthesis
B. A point mutation in the coding region of the gene coding for the P-chain
C. A frameshift mutation in the coding region of the gene coding for
the P-chain
D. A mutation in the promoter of the P-chain gene
E. A mutation in the structural gene of the P-chain
[12.4] As a medical geneticist, you analyze Talltwin’s DNA and find that he
is homozygous for thalassemia. Assuming the disease is autosomal reces-
sive, what can you deduce about the genotype of Mr. and Mrs. Talltwin?
A. Dad Talltwin is a carrier of the disease, and Mom Talltwin is normal.
B. Mom Talltwin is a carrier of the disease, and Dad Talltwin is normal.
C. Dad Talltwin is homozygous, and Mom Talltwin is normal.
D. Mom Talltwin is homozygous, and Dad Talltwin is normal.
E. Both Mom and Dad Talltwin are carriers of the disease.
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