Data are presented on seven cases of thalassemia major (six of whom were negroes) and 32 cases of thalassemia minor of whom eight had high levels (20-26 per cent) of fetal hemoglobin.
Two families with hemoglobin H disease are presented, in whom the presence of thalassemia minor could be demonstrated. The mode of inheritance of hemoglobin H disease is discussed.
Two families with an inherited double A2 fraction of hemoglobin are presented. In one of these thalassemia was also found, in the other elliptocytosis occurred concurrently.
On the basis of these findings the existence of at least five different types of thalassemia is postulated.
A study on 93 healthy students suggests a high incidence (above 3 per cent) of thalassemia minor in the West Indies.