In Nalgonda district of Telangana, Sai Chaitanya, 21, has been waiting for advancement in Indian genetic research. He has Ichthyosis, a condition caused by the mutation of a single gene, which has led to the growth of fish-like scales on his skin. Like him, many others are virtually locked into disease-prone gene pools and yearn for early detection and treatment.
In India, private enterprises engaged in genome mapping now offer testing for relative genetic risks, which effectively predict the risk of diseases such as cancer and diabetes. The costs involved vary from ₹25,000 to ₹50,000. The not-so-apparent factor in genetic test results is that they do not guarantee comprehensive or accurate prognosis for individuals.
Across India, screening for genetic diseases is a painstaking, expensive, and less-than-efficient process. This is because the country has not yet developed indigenous genetic panels specific to its native populations but continues to depend on European genetic panels, except for prenatal genetic testing, which is specific to Indian populations.
A genetic panel is developed when scientists identify mutant genes that cause diseases in specific populations. Each panel comprises already identified genes that mutated in patients, causing specific health conditions, say, a type of diabetes. Once the panel is created, screening any number of individuals for specific diseases becomes cost-effective and efficient. However, the European panels against which Indian DNA is screened mostly prove ineffective because genes that mutate and cause abnormalities are not the same among the two geographical-genetic regions. Also, about 60-70% of the mutations found in European population clusters, with reference to a single disease, might not occur among Indian people. What India needs is a pan-Indian, whole-genome sequencing exercise that will determine the genetic types which exist within its geographical boundary.
Genetic research so far has identified four linguistically defined whole population groups in India: Indo-European (North), Dravidian (South), Tibeto-Burmese, and Austroasiatic (Northeast). Each of these is further divided into 4,635 identified social groups with a specific genetic make-up, thanks to endogamy. Senior Principal Scientist at the Centre for Cellular and Molecular Biology, Hyderabad, Dr. Kumarasamy Thangaraj, who studied 263 Indian populations, said that India should develop a baseline genetic data for each of its social groups. His colleague, Giriraj Chandak, found differences in the basic disease characteristics among European and Indian patients of chronic pancreatitis and neural tube defects. An initial investment for whole genome sequencing would be ₹1,000 crore, he estimated. Further sequencing for genetic panels would increase the cost by 10 to 100 times, which may be a small price to pay for considerable dividends. Once Indian panels are made, Dr. Kumarasamy predicted a dip in cost for screening individual patients, ranging from ₹100 to ₹1,000 as against the initial sum of ₹5 to ₹10 lakh required for sequencing a family of four.
The writer is a Special Correspondent at The Hindu’s Hyderabad bureau
