A new mutant erythrocyte glucosephosphate isomerase (GPI) associated with GSH abnormality

A case of congenital nonspherocytic haemolytic anaemia associated with a new abnormal glucosephosphate isomerase (GPI), GSH (reduced glutathione) deficiency, and instability and altered carbohydrate membrane composition is reported. The only functional abnormality of the mutant enzyme seems to be a marked instability to heat, urea, and guanidine-HCl. Family studies suggest that the propositus is doubly heterozygous for a maternal gene producing an inactive enzyme and a paternal gene responsible for a structural alteration causing marked lability of the coded enzyme. Experiments of incubation of normal GPI and the propositus's GPI with oxidizing and reducing agents seem to indicate that the abnormality resides in the SH groups of the mutant GPI.