Genetic screening of 200 unrelated persons has found that 4.5% of them were carriers of cystic fibrosis gene, according to a study recently published in the journal BMC Medical Genetics. A carrier is a person that has the gene that causes the disease, but not the disease. If both carrier parents pass on the gene to their child, the child will then have the disease.
Cystic fibrosis is a life-threatening condition that causes the body’s mucus, sweat, and digestive juices to become thick and sticky, clogging up the tubes and ducts. There is no cure for the disease, but medication helps in easing the symptoms and prolonging life.
A carrier frequency of 9 in 200 persons, as was found in the pilot study by doctors from Delhi’s Sir Ganga Ram Hospital, will mean a disease prevalence of 1 in 2,000 persons. This is much higher than the earlier estimated prevalence as the disease was considered to be rare in the Indian population.
“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 new-born screening is being done. Sir Ganga Ram Hospital is planning to add CF to the existing new-born screening programme,” said Dr I C Verma, senior consultant, Institute of Medical Genetics and Genomics at the hospital.
The study found that 26% of the persons screened were carriers of one or more genetic disorders. The analysis of the genetic sequencing of the individuals was done between October 2016 and June 2018 in partnership with Medgenome Laboratories in Bengaluru.
The carrier frequency was highest for congenital deafness as 12 persons were found to be carriers of one of the four genes the doctors tested for. With three persons carrying the gene for Pompe Disease – a condition that leads to an abnormal build-up of glycogen (sugar molecule) inside cells impairing the work of organs tissues – was the third common genetic disorder.
None of the 88 partners screened were carriers of the same disorder, the study found.
“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 the same caste/community and presence of consanguineous marriages,” said Dr Sunita Bijarnia-Mahay, one of the authors and a senior consultant at the Institute of Medical Genetics and Genomics.
Dr Ratna Puri, the chairperson of the Institute of Medical Genetics and Genomics, said: “This is a new finding and the high carrier frequency of Cystic Fibrosis shall be verified in a larger population sample soon.”