A rather technical (but surprisingly easy to read) new paper that may have some interest for those interested in global and East Asian population genetics:
Haiyi Lou, Shilin Li et al., A Map of Copy Number Variations in Chinese Populations. PLoS ONE 2011. Open access.
They begin explaining what copy-number variations (CNVs) are:
Copy number variation (CNV) is a type of global genetic variations in human genome, defined as a segment of DNA larger than one kilobase presenting copy-number differences by comparison of two or more genomes. One single or co-effects of multiple genomic rearrangements such as deletion, insertion, duplication and unbalanced translocation are likely to cause CNVs. By changing gene dosage, interrupting coding sequences, and influencing neighboring gene regulation, CNVs can impact on gene expression and phenotypes.
There are several graphics of interest but I have selected this one:
|Fig. 4 CNV sharing (click to expand)|
Why? Because it highlights how minor racial or stock defining genetics markers are. Even in the ‘three races’ graph (A), the number of specific non-singleton (red) shared elements is very small, with most of the variation being shared across ‘races’ or restricted to individual (singleton) diversity. It is not much more what I share with another European than what I share with an African or Asian.
When you go to more specific ethnic differences (B), the ‘stock’ shared bloc becomes even smaller.
Interestingly, there is no particular intensity of sharing between Europeans and East Asians, each of them sharing more with Africans than with each other. This probably implies that the early Eurasian population that produced both was never truly differentiated from that of Africa.