Congenital nonspherocytic hemolytic anemia with an unstable hexokinase variant.

We report a family with a new hexokinase variant that gives rise to nonspherocytic hemolytic anemia in one apparently homozygous family member. The variant enzyme has a normal pH optimum, normal reaction kinetics, and normal electrophoretic properties, but has reduced activity and is apparently inactivated rapidly as the affected erythrocytes age.