Red blood cell hemoglobin is used to transport oxygen from the lungs to the tissues. It consists of two alpha chains and two beta chains. Hemoglobin C (Hb C) is an abnormal hemoglobin resulting from a beta chain mutation. The gene responsible for beta chain synthesis is present in two copies on the chromosomes. Very rare individuals with both copies of the mutated gene (homozygous) will have a high percentage of Hb C. Individuals with a single mutated copy (heterozygous or “trait carriers”) will have a moderate level of Hb C. This mutation is more common in individuals of African origin (2% to 3% of the population carries the Hb C trait).
In carriers of the trait and even in individuals who are homozygous for the mutation (who have two copies of the defective gene), the disease is relatively benign, most often with mild hemolytic anemia and a slight increase in spleen volume.