A multi-gene panel testing has emerged more of a necessity than a choice in order to make the right diagnosis. It becomes more significant when the clinical indications are highly overlapping across various disease conditions, write Senior Scientist Aparna G and Ashraf U Mannan, Director – Medical Genetics and Genomics, Strand Life Sciences Pvt. Ltd., Bangalore, as they explain the benefits of multi-gene testing by next-generation sequencing over the single gene or mutation specific testing
A disease is considered to be ‘rare’ when it affects one in about 2,000 individuals in the population. There are anywhere between 5,000 and 8,000 diseases that are considered to be ‘rare diseases’ according to WHO statistics. Although individually rare, collectively, the incidence of rare diseases could be as high as 6-8 per cent in certain populations. In developing countries like India, owing to the social structure, high birth rate and high degree of consanguinity, about half a million children are born every year with rare disorders.
Nearly 80 per cent of rare diseases are considered to be genetic diseases, where due to mutation in a gene, the normal function of the protein (encoded by the gene) is lost or the protein acquires abnormal function (gain-of-function), which results in a disease. A multi-centric study on Indian population showed that the frequency of newborns with malformations, such as neural tube defects and musculoskeletal disorders were upto 2 per cent, while other genetic conditions such as beta-thalassemia, metabolic disorders were as high as one in 2,500. One of the major reasons for referral to genetic centres is seen to be for reproductive genetics, comprising prenatal diagnosis, recurrent abortions, infertility, and even multiple congenital anomalies.