Hemoglobin C (HbC) is a common hemoglobin variant in parts of West Africa. What amino acid substitution characterizes HbC?

• A β6 Glutamate → Lysine ✓
• B β6 Glutamate → Valine
• C β26 Glutamate → Lysine
• D β121 Glutamate → Lysine

Explanation

HbC results from β6 Glu→Lys substitution (same position as HbS but with lysine instead of valine). HbS is β6 Glu→Val. HbE is β26 Glu→Lys. HbC causes mild hemolytic anemia and target cells; HbSC disease is a compound heterozygote with significant clinical severity. The position and nature of the substitution determine the clinical phenotype.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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