Compound heterozygosity for two genotypes of alpha-thalassemia-2: hematological, biosynthetic and DNA studies.

Hemoglobin and DNA gene analyses were carried out in two Black Canadian families. In Family Q, both the parents and the brother were found to be heterozygotes for alpha-thalassemia-2 with the following alpha-genotypes: -alpha 3.7/alpha alpha, -alpha 4.2/alpha alpha and -alpha 4.2/alpha alpha, respectively. In Family C, the mother was found to be a homozygote for alpha-thalassemia-2 with the alpha-genotype of -alpha 3.7/-alpha 3.7. In both families, the propositi were compound heterozygotes for alpha-thalassemia-2 with the alpha-genotype of -alpha 3.7/-alpha 4.2. The propositus in Family C was also a sickle cell trait carrier. The usefulness of DNA gene analyses in family studies of hemoglobinopathy was discussed.