All are true regarding paroxysmal nocturnal haemoglobinuria, except:
**Core Concept**
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells, bone marrow failure, and the potential for blood clot formation. It is caused by a mutation in the PIGA gene, leading to a deficiency of the complement inhibitor CD55 on the surface of blood cells.
**Why the Correct Answer is Right**
PNH is caused by a mutation in the PIGA gene, which is responsible for the synthesis of the glycosylphosphatidylinositol (GPI) anchor. The GPI anchor is necessary for the attachment of many proteins, including CD55, to the surface of blood cells. A deficiency of CD55 on the surface of blood cells makes them more susceptible to complement-mediated lysis, leading to the destruction of red blood cells and the clinical manifestations of PNH.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, but we can infer that it should be a true statement about PNH.
**Option B:** Not applicable, as the correct answer is not provided.
**Option C:** Not applicable, as the correct answer is not provided.
**Option D:** Not applicable, as the correct answer is not provided.
**Clinical Pearl / High-Yield Fact**
A key feature of PNH is the presence of a clonal population of hematopoietic stem cells that are resistant to the complement-mediated lysis. This leads to the destruction of red blood cells and the clinical manifestations of PNH.
**Correct Answer:** A.