1. The genetic, clinical and hematologic features of an atypical chronic hemolytic anemia in two siblings of a French Canadian family have been described.
2. The anemia is normocytic, normochromic and not associated with any characteristic morphologic abnormality of the red cells.
3. Slight increases in osmotic and incubated mechanical fragility, as well as a more definite increase in aumtohemolysis were found which could not be demonstrated after splenectomy.
4. The survival time of normal red cells was shortened before splenectomy in one patient. Normal red cell survival was demonstrated in both patients after splenectomy.
5. The features which differentiate this hemolytic anemia from hereditary spherocytosis are discussed.
6. French or French Canadian ancestry has been noted in some of the reported patients most similar to our own.
7. The association of this type of hemolytic anemia with blood group A has been confirmed in our patients.
8. Splenectomy decreased the severity of the hemolytic process in both patients. This benefit may have resulted from removal of an extracorpuscuar hemolytic mechanism.