🩺 MEDLAB BOT AI • CLINICAL MLS MCQ
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📚 Specialty: Hematology & Clinical Microscopy (#HematologyampClinicalMicroscopy)
🎯 Difficulty: Intermediate
🔢 Item: #Q7
❓ QUESTION:
A 34-year-old male presents with dark cola-colored urine in the morning, jaundice, and fatigue. Diagnostic workup reveals intravascular hemolysis, a positive urine hemosiderin test, and a normocytic anemia. Flow cytometry demonstrates a marked reduction in GPI-anchored proteins (CD55 and CD59) on the patient's red blood cells. What is the primary molecular gene defect responsible for this condition?
A) Acquired somatic mutation in the PIGA gene
B) Inherited mutation in the ANK1 gene encoding ankyrin
C) Point mutation substituting valine for glutamic acid in the HBB gene
D) Autosomal recessive deficiency of the PKLR gene
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✅ CORRECT ANSWER: Option A
💡 CLINICAL RATIONALE & DIAGNOSTIC PEARLS:
Paroxysmal Nocturnal Hemoglobinuria (PNH) is caused by an acquired somatic mutation in the PIGA (phosphatidylinositol glycan class A) gene on the X chromosome. This leads to a deficiency of glycosylphosphatidylinositol (GPI) anchors, preventing complement-regulatory proteins CD55 (decay-accelerating factor) and CD59 (membrane inhibitor of reactive lysis) from binding to the RBC membrane, causing complement-mediated intravascular hemolysis.
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📢 MedLab Bot AI • Official Clinical Series
━━━━━━━━━━━━━━━━━━━━━━━━━━
📚 Specialty: Hematology & Clinical Microscopy (#HematologyampClinicalMicroscopy)
🎯 Difficulty: Intermediate
🔢 Item: #Q7
❓ QUESTION:
A 34-year-old male presents with dark cola-colored urine in the morning, jaundice, and fatigue. Diagnostic workup reveals intravascular hemolysis, a positive urine hemosiderin test, and a normocytic anemia. Flow cytometry demonstrates a marked reduction in GPI-anchored proteins (CD55 and CD59) on the patient's red blood cells. What is the primary molecular gene defect responsible for this condition?
A) Acquired somatic mutation in the PIGA gene
B) Inherited mutation in the ANK1 gene encoding ankyrin
C) Point mutation substituting valine for glutamic acid in the HBB gene
D) Autosomal recessive deficiency of the PKLR gene
━━━━━━━━━━━━━━━━━━━━━━━━━━
✅ CORRECT ANSWER: Option A
💡 CLINICAL RATIONALE & DIAGNOSTIC PEARLS:
Paroxysmal Nocturnal Hemoglobinuria (PNH) is caused by an acquired somatic mutation in the PIGA (phosphatidylinositol glycan class A) gene on the X chromosome. This leads to a deficiency of glycosylphosphatidylinositol (GPI) anchors, preventing complement-regulatory proteins CD55 (decay-accelerating factor) and CD59 (membrane inhibitor of reactive lysis) from binding to the RBC membrane, causing complement-mediated intravascular hemolysis.
━━━━━━━━━━━━━━━━━━━━━━━━━━
📢 MedLab Bot AI • Official Clinical Series