Types of G6PD Deficiency

G6PD deficiency has many gene variants. They differ in how low the enzyme level is and how often problems occur. Doctors often describe them in simplified classes.

WHO classes (simplified)

• Class I. Very severe deficiency with chronic haemolysis. Rare.
• Class II. Severe deficiency (less than about 10 percent of normal enzyme activity). Haemolysis with common triggers. Found in Mediterranean and some Asian variants.
• Class III. Moderate deficiency (about 10 to 60 percent). Haemolysis with strong triggers only. The common African-type variant (G6PD A-) falls here.
• Class IV. Normal activity, no clinical problem.
• Class V. Increased activity, not a problem.

Common named variants

• G6PD Mediterranean: often severe, with a high risk of reactions to fava beans and drugs
• G6PD A-: milder, mainly triggered by drugs and infections
• Variants seen in South and South-East Asia, such as Mahidol and others, with a range of severity

The exact variant is found only by gene testing, which is not usually needed for care.

By clinical picture

• Asymptomatic. The most common. Normal until a trigger.
• Acute haemolytic anaemia after a trigger
• Neonatal jaundice in newborns
• Chronic non-spherocytic haemolytic anaemia, rare and severe

Carriers and females

Females may be carriers with mild or no symptoms, or partially or fully deficient.

Ayurvedic naming

Ayurveda has no equivalent. Pallor and yellowness are discussed under pandu and kamala, but these are traditional, interpretive categories and not the same condition.

Why the type matters

A more severe variant means stricter avoidance of triggers. Ask your doctor what your result means for you.