Copy number at CCL3L1 is one of the genetic predictors of HIV susceptibility in humans (Gonzalez et al), with individuals with copy number higher than the population median being less susceptible. A new paper at PLoS Genetics shows that the gene is also copy number variable in rhesus macaque, and that this variation is also responsible for differences between individuals in susceptibility (to SIV, the simian form of HIV) in macaques. One of the interesting things about this story is that while differences between populations in average copy number may be predictive of the average population susceptibility in macaques (Indian macaques have on average lower copy number and are more susceptible than Chinese Macaques) this does not appear to be the case in humans, despite a relatively large difference in average copy number between human populations.
The other nice thing about the study is that it points to CNVs as a source of 'repeatable' phenotypic variation across species, the high rate of polymorphism at CNVs means that a CNV associated with a phenotype in one species may often be polymorphic and associated with similar phenotypic variation in other species. As more associations between CNVs and phenotypes are discovered this may allow them to be relatively easily followed up across a range of species (like for example amino-acid mutations in MC1R).
Degenhardt et al. Copy Number Variation of CCL3-like Genes Affects Rate of Progression to Simian-AIDS in Rhesus Macaques (Macaca mulatta) PLoS Genetics 2009
Gonzalez et al. The influence of CCL3L1 gene-containing segmental duplications on HIV-1/AIDS susceptibility. Science 2005
Saturday, January 24, 2009