Hemoglobin C disease is a hemoglobinopathy (see Sidebar 1: Anemias Caused by Hemolysis: Hemoglobinopathies) that causes symptoms similar to those of sickle cell disease, but milder.

Of blacks in the US, 2 to 3% have the trait, which is asymptomatic. Symptoms in homozygotes are usually similar to those of sickle cell disease, but milder. However, the abdominal crises of sickle cell disease do not occur, and the spleen is usually enlarged. Splenic sequestration is possible.

Hemoglobin C disease is suspected in all patients with a family history and in black patients with clinical features suggesting sickle cell disease, particularly in adults with splenomegaly. The anemia is usually mild but can be moderately severe. The smear is normocytic, with 30 to 100% target cells, spherocytes, and, rarely, crystal-containing RBCs. Nucleated RBCs may be present. The RBCs do not sickle. On electrophoresis, the Hb is type C. In heterozygotes, the only laboratory abnormality is centrally targeted RBCs.

No specific treatment is recommended. Anemia usually is not severe enough to require blood transfusion.

Last full review/revision February 2009 by Alan E. Lichtin, MD

Content last modified September 2010