Biochemical Variants of Glucose-6-Phosphate Dehydrogenase Giving Rise to Congenital Nonspherocytic Hemolytic Disease

Abstract

Abstract Previous investigations have shown considerable biochemical heterogeneity in the glucose-6-phosphate dehydrogenase of G-6-PD deficient patients with congenital hemolytic disease. The red cells of four subjects with this disorder and of some family members have been investigated. The G-6-PD of the first subject was different than any previously described mutant enzyme and was named Albuquerque. It resembled the Oklahoma variant of G-6-PD, but the elevation of the Km values for TPN and G-6-PD were less, the pH optimum was slightly different, the enzyme activity of the red cells was much lower, and the enzyme had marked thermal lability. The second patient also showed the presence of a new type of variant, which has been named Duarte. This enzyme was characterized by a marked shift of the pH optimum to the acid side, with otherwise normal kinetic and electrophoretic characteristics. The other two patients were found to have enzymes which appeared to be identical to the previously described Chicago variant and Mediterranean variant. The reasons why patients with Mediterranean variant may sometimes show congenital hemolytic disease are discussed.