Question:medium
Chronic non-spherocytic hemolytic anemia is seen in which WHO class of G6PD deficiency?
Chronic non-spherocytic hemolytic anemia is seen in which WHO class of G6PD deficiency?
Show Hint
The most severe variant with under 10 percent activity haemolyses for life.
Updated On: Jun 24, 2026
- Class I
- Class II
- Class III
- Class IV
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: The World Health Organization sorts G6PD variants by how little enzyme remains and how badly the red cells break down. The variant that gives ongoing, lifelong (congenital non-spherocytic) haemolysis is Class I, making option a correct.
Step 2: In Class I the residual enzyme activity is under $10\%$ of normal, frequently because mutations sit at the substrate or NADP binding pockets, so red cells cannot survive even routine oxidative stress and haemolyse continuously without any trigger.
Step 3: Class II (such as G6PD Mediterranean) shares severe deficiency but haemolyses only in bursts after oxidant exposure, while Class III (G6PD A-) carries a milder 10 to 60 percent deficiency with occasional drug- or infection-induced episodes.
Step 4: Class IV has essentially normal enzyme with no haemolysis and Class V actually shows raised activity; both are clinically silent. Hence only Class I explains chronic non-spherocytic haemolytic anaemia.
\[\boxed{\text{Class I}}\]
Step 2: In Class I the residual enzyme activity is under $10\%$ of normal, frequently because mutations sit at the substrate or NADP binding pockets, so red cells cannot survive even routine oxidative stress and haemolyse continuously without any trigger.
Step 3: Class II (such as G6PD Mediterranean) shares severe deficiency but haemolyses only in bursts after oxidant exposure, while Class III (G6PD A-) carries a milder 10 to 60 percent deficiency with occasional drug- or infection-induced episodes.
Step 4: Class IV has essentially normal enzyme with no haemolysis and Class V actually shows raised activity; both are clinically silent. Hence only Class I explains chronic non-spherocytic haemolytic anaemia.
\[\boxed{\text{Class I}}\]
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