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Distribution of β-Thalassemia Mutations in the Indian Population Referred to a Diagnostic Center

2000; Taylor & Francis; Volume: 24; Issue: 3 Linguagem: Inglês

10.3109/03630260008997526

1532-432X

F. E. E. Vaz, C. B. Thakur, Monisha Banerjee, Sudha G. Gangal,

Blood groups and transfusion

Hemoglobinopathies are the most commonly inherited genetic disorders in India. Population screening has identified certain communities in India with high risk of β-thalassemia, the prevalence of carrier status in some being as high as 17%. Over a period of 6 years we have conducted DNA analysis on 1,233 carriers of 23 β-thalassemia mutations and Hb E, using the amplification refractory mutation system. The studies included analyses of five common mutations for Asian Indians, namely IVS-I-5 (G→C), 619 bp deletion, IVS-I-1 (G→T), and the frameshifts at codons 8/9 (+G) and 41/42 (-TTCT). The occurrence of these was seen in 1,066 (86.45%) of the carriers referred to us, the percentage of mutations varying between 5.03–42.58%. We found codon 15 (TGG→TAG) in 47 (3.81%) samples which was also considered a common mutation in the Indian population. Rare β-thalassemia mutations were found in 87 (7.06%) individuals. We have designed five new primers and modified four primers for nine rare mutations. These were seen in nine (0.73%) samples. The β-thalassemia anomaly in 33 (2.68%) carriers remained uncharacterized. State-wide and community-wide distribution patterns of mutations indicated that IVS-I-5 (G←C) is the most common β-thalassemia allele in the Indian population. Sindhis settled in Gujrat, and Maharashtra and Lohanas from Gujrat showed a prevalence of the 619 bp deletion mutation in 49.2 and 45.5% carriers, respectively. High frequency of the IVS-I-1 (G←T) mutation was also found in Sindhis (25.5%), Punjabi Hindus (34.7%), and Lohanas (31.2%). These studies of mutation patterns in different communities have helped us in the quick identification of β-thalassemia mutations for prenatal diagnosis.