NGS shows novel variations in common genetic disorders in Indian population

December 5, 2020 0 By FM

A recent next-generation sequencing (NGS) study found novel variations in common genetic disorders in the Indian population.

The Bengaluru-based MedGenome Labs conducted the pilot study in partnership with Sir Ganga Ram Hospital, New Delhi, to determine the carrier frequency and to look for any novel mutations seen in the Indian population for common genetic disorders.

The study was conducted over a period of 22 months with a sample size of 200 unrelated individuals in North India. After pre-test genetic counselling, the 200 individuals were screened for pathogenic variants in the shortlisted 88 genes using NGS technology. These variants were classified as per the guidelines of the American College of Medical Genetics.

The study was facilitated by MedGenome Laboratories Bengaluru, who carried out the molecular analysis using NGS, and the data was re-analyzed at Sir Ganga Ram Hospital, New Delhi.

Out of the 200 participants, 52 (26%) were found to be carriers of one or more rare genetic disorders, 12 individuals (6%) were identified to be carriers for congenital deafness and 9 individuals (4.5%) were observed to be carriers for cystic fibrosis. Three individuals were detected to be carriers for Pompe disease. This study showed a higher carrier frequency for these disorders, which was contrary to the generally held view about their low prevalence in Asian Indians.

Another interesting finding was that the disease-causing variants observed for disorders such as deafness, cystic fibrosis, Pompe disease, Canavan disease, primary hyperoxaluria, junctional epidermolysis bullosa, galactosemia, medium-chain acyl CoA deficiency etc. were different from what is seen in the Western population. Thus, this pilot study highlights the importance of having a Genetic Variant Database for the Indian population.

Dr Sunita Bijarnia-Mahay, author and Senior Consultant, Institute of Medical Genetics & Genomics, Sir Ganga Ram Hospital, New Delhi, said: “By detecting genetic disorders like cystic fibrosis which were not thought to be common, we see NGS based screening tests will bring benefit to not only the young couples who would be planning a baby, but also the healthcare officials in charting out the prevention strategies for the Indian population.”

Currently, there is no carrier screening programme available in India, except for limited screening for Thalassemia and Down syndrome.

According to Dr Sheetal Sharda, senior consultant in clinical genetics, MedGenome Labs, NGS is helping to reduce the burden of genetic disorders in India. Over the past few years, the cost of NGS also has come down significantly and continues to fall. More doctors are now aware of NGS and its benefits and rely on them for genetic diagnosis.

Prof IC Verma, senior consultant & advisor, Institute of Medical Genetics & Genomics, Sir Ganga Ram Hospital, said: “In countries such as India with high rates of consanguinity and endogamy, there is inadequate data present on mutations in the community.