Distribution of beta-thalassemia mutations in three Asian Indian populations with distant geographical locations.

We have identified the beta-thalassemia alleles in 47 pediatric patients with transfusion-dependent thalassemia major from a clinic in New Delhi and in 105 heterozygous relatives. Surprisingly, only five mutations were present in 94 beta-thalassemia chromosomes with frequencies from 10 to 32%. This observation greatly facilitated the initiation of a prenatal diagnostic program. Similar studies were conducted for seven Asian Indian patients from Calgary, Canada, seven Asian Indian patients from Durban, South Africa, and from heterozygous relatives, and persons with a beta-thalassemia trait who were not related. Besides beta-thalassemia alleles, common to Asian Indian beta-thalassemia patients, some unexpected alleles were observed in the patients from South Africa, including a newly discovered frameshift at codon 15 (-T).