Gd(-) Gifu and Gd(-) Fukuoka. Two new variants of glucose-6-phosphate dehydrogenase found in Japan.

Two new glucose-6-phosphate dehydrogenase (G6PD) variants were discovered in Japan. The first, found in a 9-year-old male, was associated with chronic hemolysis and hemolytic crises after upper respiratory infections. The enzyme activity of the variant was 2.9% of normal. The patient's G6PD showed an increased utilization of substrate analogue, deamino-NADP, and thermal instability. The second variant occurred in a 7-year-old male with drug-induced hemolysis. The main enzymatic characteristics were reduced enzyme activity, being 6.4% of normal, faster-than-normal anodal electrophoretic mobility, slightly high Michaelis constant for glucose-6-phosphate, thermal instability, and biphasic pH optima. Enzymatic properties of these variants allowed each to be distinguished from previously reported variants. The first variant was designated Gd(-)Gifu and the other, Gd(-)Fukuoka.