[The detection of beta-thalassemia minor (author's transl)].

A statistical analysis was done on the levels of Hb A2 and Hb F in 1 340 normal subjects and 356 subjects heterozygous for beta-thalassemia. This study revealed that both groups had a normal distribution of Hb A2 and a gaussologarithmic distribution of Hb F. The plotted curves show an overlapping zone between the two populations. This area lies between 3.0% and 3.5% Hb A2 and between 0.2% and 1.0% Hb F. More than 97% of the heterozygotes for beta-thalassemia have a Hb A2 level situated outside the overlapping region, which permits diagnosis. Of the remaining 3%, only the "silent carriers" do not manifest the usual hematological characteristics of beta-thalassemia minor (hypochromia, microcytosis, diminished osmotic fragility, and erythrocytes with basophilic stippling). To diagnose this group it is necessary to determine globulin chain synthesis. This test is reserved for those subjects considered as "high risks."