How ancestry DNA testing is helping people better understand their roots, illnesses

30-year-old EN Pillai, a globe-trotting IT professional from Mumbai, wanted a basis to corroborate his migrant family history as told to him by his relatives. One saliva swab for an Ancestry Genetic Test and four weeks later, Pillai had his results. “His gene pool was a major match to three specific regions – Southwestern India 39.6 percent, Northern India 18.6 percent and Central Asia 16.2 percent,” explains Rajesh K Arya, the business manager of DNA Forensics Laboratory, Mumbai, where Pillai’s test was conducted. “Pillai’s first lineage movement seems to be from Pakistan to India and from North India to Southwest India. His second lineage movement was from Tajikistan to West China and from China to North India," he adds.

Nirmal Thomas (name changed) is a businessman in his early 30s and has always been curious about his roots. “I knew that I had diverse origins after having heard various conversations in the family and through some personal research. My information was that my ancestors had originally migrated from Yemen, were traders with the West Coast of India, and had settled here centuries ago. I wanted scientific factual data on exactly how my ancestry played out, and that’s why I took the Ancestry Genetic Test from Xcode Life in Chennai," he says.

Speaking about the findings, Nirmal says, “The test revealed my ancestry was over 60 percent South Asian, and more specifically, majorly 'Ancestral North Indian'. It also showed that a quarter of my ancestry was a match with non-South Asian populations, specifically Europeans, which also might include certain Middle Eastern populations! This proved my initial research to be accurate.”

. Pixabay

This type of genetic testing presents the mosaic of different ancestries that we are made of. Pixabay

Ancestry genetic tests are categorised under consumer or personal genomics and are based on The Human Genome Project (HGP). HGP was carried out in different organisations across the globe which sequenced DNA collected from a range of individuals, all of which came together to create a ‘reference’ genome that people could be tested against.

When it comes to the sequencing of DNA and the various methods used for individuals looking to sequence their DNA for information, Dr Amol D Raut, CEO, GeneSupport, Pune, says the following tests can be used:

1. Y chromosome testing to find ancestry in the direct paternal line
2. Mitochondrial DNA testing to find ancestry in the maternal line
3. Single nucleotide polymorphism (SNP) testing for the most common type of genetic variation found among people

The sequence of an individual’s DNA is compared with that of others who have taken the tests. This helps provide an estimate of a person's ethnic background, right down to specific communities as well. For example, a segment of DNA may show that genetically the individual is 35 percent Indian, 25 percent South Asian, 10 percent African, 10 percent North American, 10 percent Caucasian and 10 percent 'unknown'. However, accuracy here depends on the vastness of the database. The larger the database for a specific reference, the more accurate the results.

“The polymorphisms (genetic variations) that are used as underlying patterns of variation are unique for each population,” explains Dr Anabhala Basu, associate professor at the National Institute of BioMedical Genomics, Kalyani. “These patterns make individuals identifiable to population/ancestry/ethnicity labels. Labelling of the reference databases is usually company-specific and depends on the customer base. The more the variety and the number of customers, the more confident and detailed are the estimates," she adds.

Now with over 300 tests to its credit, Xcode Life in Chennai is the first organisation in the world to focus on South Asian ancestry mapping in particular. Dr Saleem Mohammed, founder and CEO of Xcode Life, breaks it down. “Xcode Life’s ability to provide details of South Asian ancestry comes from a reference base of over 5000 people, which continues to grow. The idea is to grow the database to over a million, to begin with. Across several thousands of years, our ancestors have left certain genetic footprints or specific divergent points. With ancestry genetic testing, we can now pinpoint exactly where these divergences took place, and how long ago, too," he explains. This helps people to get answers to questions about heritage, ancestry and origin.

“I think the understanding one gets from an ancestry test has the the ability to awaken the individual’s past," says Dr Anabhala. “It is the primal quest to find out who we are and where we come from. It presents the mosaic of different ancestries that we are made of. That it also provides a window into understanding disease and health is a bonus. For example, the carrier frequency of Tay-Sachs disease among the Ashkenazi Jewish population is 1 in 27 as compared to a 1 in 300 ratio in other populations. In such cases, the probability of a child inheriting the disease from their parents is higher. Such knowledge is invaluable," she says.

Another research about a fishing community in Pakistan, whose DNA was sequenced, was published a few years ago. It was found that they had a gene mutation which gave them the advantage of having very low levels of triglycerides, despite having a diet rich in cholesterol. Such knowledge can used to design drugs that can bring down the presence of those genes in people who have high levels of triglycerides. And this is just the tip of the iceberg.

Ancestry genetic testing shows that deep down, we are all hybrids at varying levels who share a common origin. This knowledge is still at a nascent stage, but as our awareness increases, the rigid social structure that we are accustomed to be bound to will loosen up. The medical benefits that can be derived from such information are a brilliant additional advantage.

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Updated Date: Apr 18, 2018 13:53:20 IST

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