The only patients having their genome sequenced are those with certain cancers or rare diseases. In some cases, family members may also be asked to participate. To take part, a patient must first be referred by a consultant, before being taken through an extensive consent process to ensure they know what participation in the project means. As well as the genome sequence, Genomics England asks for access to a patient’s lifetime medical records so that links can be made between their genetics and their individual disease. The NHS has made it very clear that, for many participants, taking part in this project won’t help them treat their disease. But it is hoped that the information they provide will go on to help treat others in the future.
The 23rd pair of chromosomes is comprised of sex chromosomes – X and Y chromosomes that determine whether you’re male (XY) or female (XX). Traits like red-green color blindness, male pattern baldness and hemophilia are specifically linked to X or Y chromosomes and are called sex-linked characteristics. All of those examples, and most other sex-linked traits, are X-linked and more common in males, who only have one X chromosome. Many DNA tests isolate Y DNA in males to show consumers their paternal haplogroup. Since the Y chromosome is directly inherited from father to son, it is possible to trace direct paternal lineage for many generations.
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.