Genetic counseling and genetic heterogeneity in the thalassemias

Abstract
In this study, we have compared the hemoglobin A2 levels (Hb A2) of α‐thalassemia carriers (‐α/‐α and ‐α/αα genotypes) with those of double heterozygotes for δ+ and β° thalassemia genes, who were identified by family studies and polymorphic restriction site analysis within the β‐globin gene cluster. We found that double heterozygotes for the δ+ and β° thalassemia have significantly (p2 levels as compared with carriers of α‐thalassemia. This finding has practical implications in the genetic counseling of subjects with a thalassemia‐like phenotype associated with normal or borderline Hb A2 levels.