A propositus, the offspring of a first-cousin marriage, was presented with severe hemolytic anemia, splenomegaly, jaundice, and growth retardation. Marked basophilic stippling of erythrocytes was shown by Wright’s stain. Erythrocyte 5′-nucleotidase activity was found markedly decreased, whereas red blood cell glucose-6-phosphate dehydrogenase activity was elevated as the reduced glutathione level. His growth and anemia improved following splenectomy. His sister was also similarly affected.