Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the commonest red cell 
enzymopathy in humans and has an X-linked inheritance. It has been reported from 
India more than 30 years ago and the prevalence varies from 0-27% in different 
caste, ethnic and linguistic groups. The major clinical manifestations are drug 
induced hemolytic anemia, neonatal jaundice and chronic non-spherocytic 
hemolytic anemia. Individuals with G6PD deficiency have a selective advantage 
against falciparum malaria. Thirteen biochemically characterized variants have 
been reported from India. At the molecular level, G6PD Mediterranean is the most 
common deficient variant in the caste groups whereas, G6PD Orissa is more 
prevalent among the tribal of India. The third common variant seen in India is 
G6PD Kerala-Kalyan.