Genotype of subjects with borderline hemoglobin A2 levels: Implication for, β‐thalassemia carrier screening

In this study, we have defined by molecular analysis, the α, β, and δ globin genotype in a group of individuals with normal or thal‐like red cell indices but borderline hemoglobin (Hb)A2 levels, who were identified in a program for β‐thal carrier screening. In 37 of 125 individuals with borderline HbA2 levels, we detected a molecular defect in the β, in both the δ and the β, or in the α globin gene. Specifically seven of these subjects were carriers of the −101 C T mutation, ten of the IVSI nt6 T C mutation, 16 were double heterozygotes for δ and β thal, and two had the triple α globin gene and two the single α globin gene deletion. From these results, we may conclude that subjects with borderline HbA2, particularly when they marry a typical β‐thal carrier, should be extensively investigated in order not to miss heterozygous β‐thalassemia. © 1994 Wiley‐Liss, Inc.