People diagnosed with ______ B thalassemia have some protection against coronary heart disease and symptomatic CVD at 30-40% the rate of the other type.

• A. Heterozygous
• B. Homozygous
• C. Compound heterozygous
• D. Silent carrier

Answer: (A)

The main idea is that disease severity in beta-thalassemia depends on genotype. People who are heterozygous have the beta-thalassemia trait with only mild or no anemia and typically do not require transfusions, so they don’t accumulate the iron overload and cardiomyopathic stress seen in the more severe form. The homozygous form, beta-thalassemia major, causes chronic anemia and often lifelong transfusions, leading to iron deposition in the heart and cardiomyopathy, which markedly raises the risk of coronary heart disease and other symptomatic cardiovascular problems. Because these cardiotoxic and high-output stress factors are largely absent in heterozygotes, their rate of CHD and symptomatic CVD is substantially lower—about 30-40% of the rate seen in the homozygous group. So the heterozygous state best explains the protective effect described.