the hemoglobin c trait is the presence of an abnormal type of the oxygen-carrying substance in red blood cells (hemoglobin) called hemoglobin c. people who have hemoglobin c trait also have some normal hemoglobin (hemoglobin a) so they rarely have problems from the condition, but they can pass on the trait to their children.
a person who has hemoglobin c with little or no normal hemoglobin has hemoglobin c disease. hemoglobin c disease produces a mild type of anemia that occurs because the red blood cells containing abnormal hemoglobin break down prematurely.