Gd (+) Laguna, a new rare glucose-6-phosphate dehydrogenase variant from Brazil.

A new G6PD variant, designated Gd (+) Laguna, was found in a 9-year-old Brazilian boy of Portuguese ancestry suffering from an iron-refractory anemia. The red cell enzyme activity of the subject was 64%. The mutant enzyme showed slower electrophoretic mobility, increased affinity for glucose-6-phosphate, decreased affinity for NADP+, elevated utilization of substrate analogues, decreased inhibition of NADPH, normal heat stability and a biphasic pH curve. The occurrence of the variant in two non-anemic relatives of the propositus indicates that the association between this G6PD type and anemia may be coincidental.