Table 1.
WHO classification of G6PD deficiency
| Class | Level of deficiency | Enzyme activity | Prevalence |
|---|---|---|---|
| I | Severe | < 10 % enzyme activity; chronic non-spherocytic hemolytic anemia in the presence of normal erythrocyte function | Uncommon; occurs across all population |
| II | Severe | < 10 % enzyme activity with intermittent hemolysis | Varies; more common in Asian and Mediterranean populations |
| III | Moderate |
10–60 % enzyme activity Hemolysis with stressor only |
10 % of black males in USA |
| IV | Mild to none |
60–150 % enzyme activity No clinic sequelae |
Rare |
| V | None |
> 150 % enzyme activity No clinic sequelae |
Rare |