Glucose-6-Phosphate Dehydrogenase (G-6-PDH) is an X-linked disorder is the most common type of haemolytic anaemia due to an intrinsic red cell enzyme defect.Males who inherit an abnormal gene are invariably affected. Heterozygote females usually have approximately 50% G6PD enzyme activity; the random Lyonisation of X chromosomes means that rarely carrier females may be severely affected. It is most common in the Mediterranean, the Middle East, South East Asia and West Africa. It is rare among Caucasians.
METHOD Ultraviolet, Kinetic (quantitative)
The rate of formation of NADPH is proportional to the G-6-PDH activity is measured spectrophotometrically as an increase in absorbance at 340nm.
DIAGNOSTIC IMPLICATIONS Presentation is usually with an acute episode of intravascular haemolysis on exposure to certain drugs, infection or acute illness. Mediterranean forms may present with neonatal jaundice. The condition is also known as favism as sudden haemolysis may be precipitated by the ingestion of fava beans – Vicia faba. The deficiency is generally less severe in Africans and favism is rare in this population.