Clinical Classes of Glucose-6-Phosphate Dehydrogenase (G6PD) Enzyme Variants

 

Clinical classes:

(1) chronic hereditary, nonspherocytic hemolytic anemia

(2) severe enzyme deficiency

(3) mild enzyme deficiency

(4) gene mutation with normal functional activity

 

While the chronic hemolytic anemia is usually mild, some patients may have severe anemia with transfusion dependence.

 

Patients with low levels of functional activity may present following hemolysis occurring after exposure to a precipitating drug or compound.

 

Functional Level of Enzyme Activity	Interpretation
<= 25% of normal	severe
26 – 64% of normal	mild
65-150%	normal
> 150%	high activity

from page 16, WHO 1967

 

where:

• The percent activities were adjusted to remove overlap in ranges at 25% and 65%