Cause:Genetic, autosomal dominant in 75%; recessive in 25% (Nejm 1982;306:1170)

Pathophys:Rbc membrane protein ("ankyrin"—Nejm 1988;318:230) deficiency causes Na permeability increase, which increases intracellular Na so that cellular swelling results (Nejm 1986;315:1579); similar defect in nonspherocytic anemia (Nejm 1968;278:573). The swollen spherocyte is quickly phagocytized by spleen

In Europeans mainly; 5/100 000

Sx:Anemia, aplastic crisis

Si:Jaundice, splenomegaly, occasionally leg ulcers

Aplastic crisis; r/o very similar ELLIPTOCYTOSIS, secondary hemolytic anemias

Lab: Hem: Microcytic smear has spherocytes. Osmotic fragility increased, glucose corrects. Coombs test neg

Rx:

Transfuse

Surgical splenectomy helps anemia, though cellular defect remains