Features

• Haemolysis after exposure to oxidants or infection.

• Chronic non-spherocytic haemolytic anaemia.

• Acute episodes of haemolysis with fava beans (termed favism).

• Methaemoglobinaemia.

• Neonatal jaundice.

Mechanism Oxidants—^denatured Hb—►methaemoglobin—»Heinz bodies— RBC less deformable— destroyed by spleen.

2 main forms of the enzyme: normal enzyme is G6PD-B, most prevalent form worldwide; 20% of Africans are type A. A and B differ by one amino acid. Mutant enzyme with normal activity = G6PD A(+), find only in Black individuals. G6PD A(-) is main defect in African origin; 5 stability of enzyme in vivo; 5-15% normal activity. 400+ variants but only 2 are relevant clinically: type A(-) = Africans (10% enzyme activity) and Mediterranean (with 1-3% activity).

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