Chromosome-Scale Selective Sweeps and Genomic Diversity in C. elegans
Andersen, Gerke et al., Nature Genetics
Researchers at Princeton University and elsewhere discuss the effects of chromosome-scale selective sweeps on genomic diversity in Caenorhabditis elegans. Taking a high-throughput selective sequencing approach on a collection of 200 wild C. elegans strains, the team found that the nematode's "genome variation is dominated by a set of commonly shared haplotypes on four of its six chromosomes, each spanning many megabases." Further, the team reports on its population genetic modeling experiments, which showed that "this pattern was generated by chromosome-scale selective sweeps that have reduced variation worldwide; at least one of these sweeps probably occurred in the last few hundred years," it writes.
Calling GWAS Longevity Calls into Question
According to Nature's The Great Beyond blog, the GWAS published in Science last week that identified SNPs for "exceptional longevity" has generated some criticisms within the community. Critics are calling the findings of Paola Sebastiani et al. into question amid inquiries of "subtle biases" and the team's use of "different versions of the SNP chips" from Illumina, according to Nature. The Wellcome Trust Sanger Institute's Jeffery Barrett told the Guardian that "some of the genetic variants in this study are claimed to have much, much stronger effects on longevity than we've seen in similar studies of diabetes, heart disease, and cancer. For instance, the strongest single effect makes someone 10 times more likely than average to be extremely long-lived, compared to other complex diseases where typical variants only make someone, say, one and a half times as likely to be diabetic," highlighting his skepticism. According to Nature, Sebastiani says that the variants they've reported have larger effects since becoming a centenarian is a much rarer condition than having diabetes.
Last week, the New York Times' Nicholas Wade reported that DeCode Genetics' Kari Stefansson, who has run a similar experiment using a larger group of centenarians, did not find any of Sebastiani et al.'s 150 variants in his cohort.
Nature reports that Sebastiani and her team are considering "holding an online chat next Wednesday to answer questions" and to quell any confusions that their work has generated.