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A 30-year-old female patient is seen for evaluation of fatigue. Initial labs show a hemo globin of 7.6 g/dl, MCV of 106 FL. WBC of 3,200/,LLL. and platelets of 178.000/,LLL. LDH is 1 .200 U/L and haptoglobin is low. On review of symptoms, she states that her urine is dark in the morning, but clears toward the evening. Test tubes showing serial urine samples are shown below.
Which of the following is the most common pathophysiologic mechanism in PNH?
- Mutation in the PIG-A gene
- Deficiency of ADAMTS-13
- IgM antibodies to the I antigen on red blood cells
- Donath-Landsteiner antibodies
- Acquired complement deficiency
Medicine
A. PNH is an acquired hematopoietic stem cell disorder that results from somatic mutation of the PIG-A gene. The protein encoded by PIG-A gene is needed for the synthesis of glycosyl phos phatidylinositol (GPI) that serves as a membrane anchor for cellular proteins. Due to the mutant PIG-A, there is a deficiency of CDSS and CD 59, and thus peripheral blood erythrocytes derived from the abnormal clone lack the ability to restrict cell surface activation of the alternate complement path way, which results in hemolytic anemia.
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