HEREDITARY SPHEROCYTOSIS

form of congenital hemolytic anemia characterized by enlarged spleen, spherical (rather than disk-shaped) red blood cells of variable size and increased fragility of cell membrane, and a chronic, mild hemolytic anemia punctuated by episodes of severe aplastic anemia (failure of bone marrow to produce cells). Hereditary spherocytosis, most frequent of the familial anemias, is inherited as an autosomal dominant (an inherited characteristic not related to sex); it is rare in blacks and most common in north Europeans. Symptoms may be present at birth or may not appear until old age; the disease is most often identified during childhood or adolescence. Removal of the spleen results in cure of anemia in nearly all cases; the defects in blood production remain but do not cause serious disability.