Question

What is the cause of intracorpuscular defects in hemolysis?

• A. Uremic syndrome
• B. PCH
• C. PNH
• D. Portal hypertension

Answer 1

The Correct Option is C

Step 1: Decide whether each option places the defect inside the red blood cell or outside it. An intracorpuscular cause means the membrane, enzymes, or hemoglobin of the cell are themselves faulty. Step 2: PNH arises from a somatic mutation in the PIGA gene of a hematopoietic stem cell, so the resulting red cells lack the GPI anchor for CD55 and CD59 and cannot block complement, which is a defect intrinsic to the cell. Step 3: By contrast, uremia, portal hypertension, and cold antibodies in PCH all damage structurally normal red cells from the outside, so they are extracorpuscular. Step 4: The only intracorpuscular option provided is PNH. \[\boxed{\text{PNH}}\]