Triplicated alpha-globin gene loci in a Chinese family

Utilizing restriction endonuclease mapping and blot hybridization, we have determined the arrangement of the alpha-globin genes in a Chinese family. The father and mother had no obvious alpha-thalassemia symptoms, but their twin daughters suffered from HbH disease. The gene analysis showed that the mother had three alpha-globin genes in one chromosome and no alpha-globin gene in the other (alpha alpha alpha/--), the father was a heterozygote of alpha-thal2 (alpha alpha/-alpha). Their twin daughters were double heterozygotes of alpha-thall and the rightward deletion genotype alpha-tha12 (--/-alpha).