Heterozygous beta-thalassaemia with normal haemoglobin pattern. Haematologic, haemoglobin and biosynthesis study of 4 families.

Thalassaemia with normal levels of Hb A2 and Hb F and with an alpha/beta ratio higher than 1 is described in 4 families. 3 of these families show direct or indirect signs of the presence of the delta-thalassaemia gene along with the beta-thalassaemia gene. The fourth family leaves the question as to whether there is a single mutation of the deltabeta tract or a beta + delta-thalassaemia in coupling unanswered. The necessity of knowing of the existence of this thalassaemia which conceals the presence of a beta-thalassaemia gene, is stressed, above all in view of the danger that mating between a carrier of this thalassaemia and a carrier of classical beta-thalassaemia could result in the birth of children with Cooley's disease.