Which of the following is NOT seen in Paroxysmal Nocturnal Hemoglobinuria :
**Core Concept**
Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare, acquired, life-threatening disease 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 the absence of glycosylphosphatidylinositol (GPI) anchors on the surface of hematopoietic cells.
**Why the Correct Answer is Right**
PNH is characterized by the presence of hemolytic anemia, thrombocytopenia, and the potential for venous thrombosis. The disease is caused by the deficiency of GPI-anchored proteins, including CD55 and CD59, which normally protect red blood cells from complement-mediated lysis. However, the absence of these proteins leads to the destruction of red blood cells, which is a hallmark of PNH.
**Why Each Wrong Option is Incorrect**
* **Option A:** Hemolytic anemia is a common feature of PNH, so this option is incorrect.
* **Option B:** Thrombocytopenia is also seen in PNH, making this option incorrect.
* **Option D:** Venous thrombosis is a potential complication of PNH, so this option is also incorrect.
**Clinical Pearl / High-Yield Fact**
PNH is often associated with a deficiency of CD55 and CD59 on the surface of red blood cells, which makes them more susceptible to complement-mediated lysis. This is a key diagnostic feature of the disease.
**Correct Answer: D. Leukopenia**