Homozygosity for dominant form of hereditary spherocytosis.

A 6-month-old male infant with hereditary spherocytosis (HS) who was the first child of a cousin marriage is presented. The patient had splenomegaly and severe anaemia. Examination of the peripheral blood smear revealed spherocytes and the osmotic fragility of red blood cells was greatly increased. Physical examination of the parents revealed that both parents had mild anaemia, jaundice and splenomegaly. Their peripheral blood smears showed spherocytes and a few acanthocytes. Osmotic fragility of red blood cells of both parents were increased. Red cell membrane electrophoresis indicated a deficiency of ankyrin in the propositus; mild deficiency was also detected in both parents. Electrophoretic patterns of red cell membrane proteins suggested that the child was homozygous for the dominant form of HS associated with ankyrin deficiency, while both parents had the simple dominant form of the disease. Red blood cell transfusions were given to the patient starting at the age of 1 month until splenectomy was performed at the age of 1 year that resulted in complete haematological response. This observation indicates that homozygosity for dominant type of HS associated with ankyrin deficiency is life compatible and splenectomy may cure the anaemia.