A 30-year-old man is noted to be anemic, with clinical jaundice and a palpable spleen on abdominal exam. Splenectomy is the only treatment for this patient's autosomal dominant disorder. Select the most likely diagnosis.

Hereditary spherocytosis is the most common symptomatic familial hemolytic anemia and is transmitted as an autosomal dominant trait. A defect in the red cell membrane causes increased trapping in the spleen and hemolysis. Anemia, jaundice, and splenomegaly are clinical findings. Splenectomy is the only treatment. Thalassemia is transmitted as a dominant trait; anemia is the result of a defect in hemoglobin synthesis. Thalassemia major, or homozygous thalassemia, is associated with anemia, icterus, splenomegaly, and early death. Transfusions are usually required. Splenectomy may reduce hemolysis and transfusion requirements. Sickle cell anemia is hereditary hemolytic anemia. Serum bilirubin may be mildly elevated. Splenomegaly often precedes auto infraction. Splenectomy may be indicated for chronic hypersplenism or acute splenic sequestration.