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Study shows cystic fibrosis could be most prevalent genetic disorder among North Indians

Study shows cystic fibrosis could be most prevalent genetic disorder among North Indians

New delhi: Sir Ganga Ram Hospital has conducted a genetic research pilot study which shows that cystic fibrosis might be the most prevalent genetic disorder in the North Indian population, after thalassemia.

This was a pilot research project where 200 healthy individuals underwent carrier screening for 86 to 88 genetic disorders. Nine out of these 200 individuals were found to be carrying a defective gene variant for cystic fibrosis (CFTR). A carrier frequency of 9 per 200 has an expected disease prevalence rate of 1:2,000. This was an unexpected result as cystic fibrosis was not thought to be a commonly occurring genetic disorder in India.

"It was a study to look at genetic variation to find carrier status. We did not know that we'd find cystic fibrosis. The aim of the study was to find which disorder/genetic condition was more prevalent in our (north Indian) population and this was done through carrier testing because genetic disorders come from parents and for most such diseases, the parents are carriers, they don't have the disease themselves but they carry a variant or a defective gene copy," said Dr Sunita Bijarnia-Mahay, Author and Senior Consultant, Institute of Medical Genetics & Genomics, Sir Ganga Ram Hospital.

"Since cystic fibrosis affects lung functioning, poor air quality, such as is currently prevalent in most of north India, especially Delhi-NCR, considerably worsens the already life-limiting condition", she said. Apart from that, the study also found congenital deafness and Pompe disease (affects the heart and muscles) to commonly occurring genetic disorders.

Cystic Fibrosis is an inherited life-threatening disorder that damages the lungs and digestive system. As a result, the respiratory passageways get blocked.

"Since we already knew that thalassemia is the most common genetic disorder found in India, we took it out of the study. Other than thalassemia, we had no idea which were the common genetic conditions," she added.

According to Dr Bijarnia-Mahay, general consensus among doctors is that cystic fibrosis is a very rare condition in India. "But nobody knew the exact incidence. Whereas this is a common condition in the western world and there is newborn screening for it. However, the idea we had behind carrier screening was prevention, by testing and letting couples know if their child could potentially have cystic fibrosis. This study needs to be verified and we have to do more rigorous research".

Patients with CF inherit a mutated copy of the gene from both parents. If one inherits one copy then the patient is asymptomatic but is a carrier. This means there is a chance he/she can pass to the children, if the partner is also a carrier. There is no cure for CF, but medications and other therapies can ease symptoms and prolong life. The only way it can be prevented is by genetic screening.

According to Dr IC Verma, Senior Consultant & Advisor, Institute of Medical Genetics & Genomics, Sir Ganga Ram Hospital: "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."

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