A NEW GLUCOSE-6-PHOSPHATE-DEHYDROGENASE VARIANT, G6PD-ORISSA-(44-ALA-]GLY), IS THE MAJOR POLYMORPHIC VARIANT IN TRIBAL POPULATIONS IN INDIA

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) is usually foun d at high frequencies in areas of the world where malaria has been end emic. The frequency and genetic basis of G6PD deficiency have been stu died in Africa, around the Mediterranean, and in the Far East, but lit tle such information is available about the situation in India. To det ermine the extent of heterogeneity of G6PD, we have studied several di fferent Indian populations by screening for G6PD deficiency, followed by molecular analysis of deficient alleles. The frequency of G6PD defi ciency varies between 3% and 15% in different tribal and urban groups. Remarkably, a previously unreported deficient variant, G6PD Orissa (4 4 Ala-->Gly), is responsible for most of the G6PD deficiency in tribal Indian populations but is not found in urban populations, where most of the G6PD deficiency is due to the G6PD Mediterranean (188 Ser-->Phe ) variant. The K-m(NADP) of G6PD Orissa is fivefold higher than that o f the normal enzyme. This may be due to the fact that the alanine resi due that is replaced by glycine is part of a putative coenzyme-binding site.