Which enzymatic defect is known to cause increased bilirubin levels?

• A. G6PD deficiency
• B. Factor V Leiden
• C. Protein C deficiency
• D. Hemophilia A

Answer: (A)

The correct choice reflects the fact that G6PD (Glucose-6-Phosphate Dehydrogenase) deficiency is associated with a specific metabolic dysfunction that impacts the red blood cells, leading to hemolysis (the breakdown of red blood cells). This condition results in the release of hemoglobin, which is then metabolized to bilirubin. The liver usually processes bilirubin for excretion, but when there’s excessive hemolysis due to G6PD deficiency, the liver can become overwhelmed, leading to elevated levels of unconjugated bilirubin in the blood, known as hyperbilirubinemia.

In contrast, the other conditions listed—Factor V Leiden, Protein C deficiency, and Hemophilia A—are related to coagulation disorders and do not influence bilirubin levels directly. Factor V Leiden is associated with increased risk of thrombosis, Protein C deficiency involves the regulation of coagulation, and Hemophilia A pertains to deficiencies in clotting factors that affect the blood's ability to clot. None of these conditions contribute to abnormalities in bilirubin metabolism or excretion.