We have characterized the mutations in 1050 carriers of the β-thalassemia gene and analyzed their regional distribution in India. The majority of β-thalassemia carriers were migrants from Pakistan and their pattern of mutations differed from the rest. The frequency of the 619-bp deletion was 33.3% among the migrants from Pakistan, 8–17% in the northern states, and less than 5% in the other states. Among non-migrant subjects, the predominant mutation was IVS-I-5 (G→C), varying from 85% in the southern states and 66–70% in the eastern states to 47–60% in the northern states. The mutation IVS-I-1 (G→T) was observed at high frequency among the migrants from Pakistan (26.2%), but with very low/ zero frequency in the other states. Mutations at codons 8/9 (+G) and codons 41/42 (–CTTT) were distributed in all regions of India with a frequency varying from 3% to 15%. Only eight of 12 published rare mutations were observed in subjects from different parts of India. Mutations of codon 5 (–CT) and codons 47/48 (+ATCT) were found exclusively in migrants from Pakistan, and mutation –88 (C→T) was detected only in subjects from Punjab, Haryana, and Uttar Pradesh. Using the amplification refractory mutation system technique, mutations were successfully identified in 98.2% of subjects. Overall, 91.8% of the subjects had one of the five commonest mutations [IVS-I-5 (G→C), 34.1%; 619-bp deletion, 21.0%; IVS-I-1 (G→T) 15.8%; codons 8/9 (+G), 12.1%, and codons 41/42 (–CTTT), 8.7%], 5.9% of the subjects had a less common mutation, while 1.8% of the carriers remained uncharacterized. The application of this knowledge has helped to successfully establish a program of genetic counselling and prenatal diagnosis of β-thalassemia in order to reduce the burden of this disease in India.
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Received: 15 October 1996 / Accepted: 18 February 1997
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Verma, I., Saxena, R., Thomas, E. et al. Regional distribution of β-thalassemia mutations in India. Hum Genet 100, 109–113 (1997). https://doi.org/10.1007/s004390050475
- Genetic Counselling
- Prenatal Diagnosis
- Regional Distribution
- System Technique