1. The clinical and hematological features of seven cases of nonspherocytic congenital hemolytic anemia occurring in four different families are presented, together with family studies. Four cases resemble Selwyn and Dacie’s Type I and three cases their Type II. Cases in the literature similar to our cases are reviewed.
2. The Type I cases showed the following features: normocytic or slightly macrocytic anemia with mild hypochromia and some stippling; a decreased or normal osmotic fragility of fresh blood and a decreased fragility of incubated blood; a slightly increased autohemolysis corrected by glucose and by ATP. The family history was positive and clinical onset was usually in adult life. Survival studies suggest that splenectomy may result in partial remission.
3. The Type II cases showed the following features: a marked uniform macrocytosis with numerous Pappenheimer bodies (postsplenectomy); a normal osmotic fragility of fresh blood and an increased fragility of incubated blood; an increased autohemolysis uncorrected by glucose but corrected by ATP. The family history was often negative and clinical onset was usually in infancy. Splenectomy in general appeared to produce no benefit.
4. The classification and pathogenesis of these anemias is discussed. It is pointed out that Type I is not a homogeneous group, and that our cases simply represent one subgroup of this type. Type II appears to be a more homogeneous group. Preliminary biochemical studies suggest the difference in clinical types may be determined by differences in biochemical defects.