A 19-year-old man has lifelong mild hemolytic anemia with jaundice worsened by intercurrent illness. Smear shows bite cells and occasional blister cells. Enzyme assay is normal during remission. His younger brother has similar findings but their sister is unaffected and the father is affected. Which inheritance pattern fits this enzyme defect?

• A Autosomal recessive
• B Autosomal dominant with variable penetrance
• C Mitochondrial maternal transmission
• D X-linked recessive ✓

Explanation

G6PD deficiency is X-linked recessive: the G6PD gene lies on chromosome Xq28. Affected males transmit the mutation to all daughters and no sons, so an affected father with unaffected daughters and affected sons through carrier mothers matches this pedigree. Bite cells reflect splenic removal of Heinz bodies. Pyruvate kinase deficiency, by contrast, is autosomal recessive.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.