New Delhi: A pilot study on genetic research done by the Institute of Medical Genetics & Genomics of Delhi’s Sir Ganga Ram Hospital, which has been published in the BMC Medical Genetics of London, has thrown some startling results — unexpected high carrier frequency of Cystic Fibrosis revealed in genetic carrier screening of north Indian population by next generation sequencing technology.
For the first time a high carrier frequency of 4.5 per cent, which was 9 per 200, for Cystic Fibrosis (CF) has been revealed. Carrier frequency of 9 per 200 found in the study has an expected disease prevalence rate of 1:2000.
The reason it becomes interesting is because Cystic Fibrosis was considered to be very rare among the Indian population. This study not only shows prevalence of it, but also to a high extent.
The study also showed a high carrier frequency for genetic forms of Deafness and Pompe disease, among a cohort of 200 subjects from North India. The study was done in partnership with Medgenome Labs, Bengaluru.
Carrier status does not mean disease. If both husband and wife are carriers then there is a 25 per cent chance of their children suffering from the disease.
Based on this carrier rate, the prevalence of Cystic Fibrosis disease would be as high as one in 2,000 newborns. Cystic Fibrosis (CF) was considered to be very rare in the Indian subcontinent, but the current study shows its frequency to be higher than the West.
“Based on this study, Cystic Fibrosis should be added to beta thalassemia and spinal muscular disorders that should be screened in all pregnant women to prevent these diseases. It should also be added to the list of disorders for which newborn screening is being done. Sir Ganga Ram Hospital is planning to add CF to the existing newborn screening programme,” said I.C. Verma, Senior Consultant and Advisor at the Institute of Medical Genetics & Genomics, Sir Ganga Ram Hospital.
Meanwhile, Sunita Bijarnia-Mahay, Senior Consultant at the Institute of Medical Genetics & Genomics, said, “Our study also found that the disease-causing pathogenic variants in the Indian population were different from those commonly observed in the West. It is because of our unique system of marriages within same caste/community and presence of consanguineous marriages.”
Cystic Fibrosis is an inherited life-threatening disorder that damages the lungs and digestive system. It affects the cells that produce mucous, sweat and digestive juices. It causes these fluids to become thick and sticky. As a result, the respiratory passageways get blocked.
It is caused by a change in a gene called CFTR (cystic fibrosis transmembrane conductance regulator). This gene controls the flow of salt and fluids in and out of cells. If this gene doesn’t work the way it should then a sticky mucus builds in the body.
Ratna Puri, Chairperson of Institute of Medical Genetics & Genomicsin, said, “This is a new finding and the high carrier frequency of Cystic Fibrosis shall be verified in a larger population sample soon.”
Patients with Cystic Fibrosis inherit mutated copies of genes from both the parents. If one inherits one copy, then the patient is asymptomatic but is a carrier. This means there is a chance he or she can pass it to the children, if his partner is also a carrier. There is no cure for Cystic Fibrosis, but medication and other therapies can ease the symptoms and prolong life.
The only way it can be prevented is by genetic screening.