Table 2.

Variants of G6PD deficiency.

Variant	Severity of enzyme deficiency	Clinical Presentation
Class 1	Severe (<10% of normal)	Associated with chronic hemolytic anemia
Class 2 (Mediterranean and Asian variant)	Severe (<10% of normal)	Intermittent hemolysis usually due to minor exposure to oxidative stress (drugs or fava beans)
Class 3 (G6PD A− variant, the most common variant seen in people of African descent)	Moderate (10–60% of normal)	Intermittent hemolysis mostly due to significant oxidative stress
Class 4	No enzyme deficiency or hemolysis	None
Class 5	Increased enzyme activity	None