The picture above shows the relatedness of parents across different populations throughout the world; for reference, 0.065 is the average value for a first cousin mating. It comes from a paper out in pre-publication this week at the European Journal of Human Genetics, which estimates the level of inbreeding (or “consanguinity”) of parents by looking for sections of the genome where individuals inherit an identical piece of DNA from each parent. Such “runs of homozygosity” are a sure sign of inbreeding, as both parents will have inherited the bit of DNA from a recent common ancestor: the number and length of these sections can be used to find out how many generations ago the common ancestor lived, i.e. how closely related the parents were (cousins share a grandparent, second cousins a great-grandparent, and so on). In the plot above, we can see a high degree of cousin-marriage in Middle-Eastern cultures, and somewhat more sadly, high degrees of inbreeding in the Native American populations, due to the collapse in their population sizes. [LJ]
For those interested in gene-by-environment interactions the latest issue of Trends in Genetics includes a review article by Carole Ober and Donata Vercelli on the challenges of this area, illustrated by examples from asthma research. In particular they highlight the difficulties of moving G-by-E studies from examination of known candidate genes to genome-wide association. More interactions, this time of the protein-by-protein kind, are the subject of an article by Soler-Lopez et al. in this month’s Genome Research. They looked for interactions relating to Alzheimer disease using a combination of computational and experimental strategies, identifying 66 genes that putatively interact with known AD-related genes. The authors focus on the potential roles of neuronal death regulation and pathways linking redox signalling to immune response in AD pathology. [KIM]
This week, Debbie Kennett pointed out two separate indicators of the growing numbers of people beginning to engage with their genetic information. Firstly, an article in the Mercury News notes that an astonishing 470,000 people have now participated in The Genographic Project, which provides information on a relatively small number of markers on the Y chromosome and mitochondrial DNA to infer an individual’s deep ancestry. Secondly, a more modest but nonetheless impressive figure: 23andMe’s Alex Khomenko noted on Quora that more than 75,000 individuals are in 23andMe’s database as of last month. [DM]
Charles Warden has posted a largely positive three-part review of his experience undergoing testing by 23andMe. He first compares his 23andMe interpretation with the results provided by the free software Promethease; then emphasises the need to consider genetic results in the context of other risk factors; and finally, he takes issue with 23andMe’s presentation of trait prediction. While Warden’s point about the need to consider environmental as well as genetic risk factors is important, it’s worth noting that there currently isn’t enough information about the interactions between genes and environment to build all of these factors into a single predictive model (as noted in the article by Carole Ober discussed above by Kate). [DM]
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