Cause:Genetic, autosomal recessive (trait may manifest if coincident with sickle trait)

Pathophys:Single amino acid alteration in ß chain of Hgb A

In black Africans, perhaps up to 15% with disease in some areas; 3% of US black population

Si: Splenomegaly; compensated hemolytic anemia

Increased thrombotic disease; proliferative peripheral retinopathy

r/o hemoglobin D disease, similar but rarer

Lab: Hem:Hemolytic anemia with elevated reticulocytes and bilirubin, and erythroid hyperplasia in marrow; peripheral smear shows targets, microcytes; Hgb electrophoresis shows characteristic Hgb C

Rx:Transfusions for crisis; folic acid