Although the project states that most participants won’t receive any useful information, patients will be told if something is found in their genome that is relevant to the treatment, explanation or diagnosis of their condition. They can also choose to learn if they have a genetic risk factor for another disease, such as the BRCA1 gene mutation that can cause breast cancer. Genomics England will only look for risk factors that are linked to a disease that can be treated or prevented. Untreatable conditions, such as Alzheimer’s, are not looked for.
While men can trace both their maternal haplogroup (from mitochondrial DNA) and their paternal haplogroup (through the Y chromosome passed down from their father), women can only trace their maternal haplogroup (through the mitochondrial DNA passed down from their mother). This is because the paternal haplogroup is traced through the Y chromosome, which women do not inherit.
In testing, we found that many tests have much more specific and detailed results for European ancestry than anywhere else. This is due more to the diversity of the database than size. For example, AncestryDNA has the largest database with over 10 million samples yet results for Asian ancestry are markedly less specific than results from several companies with much smaller databases, including 23andMe and Living DNA. Instead of pulling reference samples directly from the existing database, however, many companies seek out high quality data with special research projects. 23andMe, for example, offers its Global Genetics project, which sends free kits to people with all four grandparents born in certain countries that are underrepresented in the database.
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More controversially, some of these kits profess to tell you your biological (as opposed to actual age) by measuring the length of your telomeres (in basic terms, the caps at the end of each strand of DNA that protect chromosomes, like plastic tips at the end of shoelaces). Other tests, such as 23andMe, predict higher risks of developing serious conditions, such as multiple sclerosis, Alzheimer’s and Parkinson’s, including the test for BRCA1/BRCA2 (breast and ovarian cancer) that Angelina Jolie famously underwent, going on to have a preventative double mastectomy and surgery to remove her ovaries.