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.
AACC: Assessing the Cost-Effectiveness of PGx Testing
In several talks given here at the American Association for Clinical Chemistry's annual meeting in Anaheim, Calif., investigators have highlighted the importance of conducting prospective clinical trials to determine the cost-effectiveness of pharmacogenomic approaches for personalized medicine. Speaking to an audience of pathologists, clinical chemists, medical technologists, and others, Columbia University Medical Center's Alex Rai said that issues related to regulation, education, standardization, and reimbursement remain challenges for the adoption of genetic testing for disease stratification and therapeutic drug management. In order for the latter to be achieved, Rai noted, "payers will need to appreciate the importance of biomarkers and pharmacogenetic testing in reducing health care costs."
In a another session, Luke Chen, CEO of the Xizhi, Taiwan-based Pharmigene, spoke of what he called the "most clear case" for genetic testing to date. Chen described a 5,000 patient study that investigated the cost-effectiveness of HLA-B*1502 genotyping for individuals prescribed carbemazepine who are at risk for developing Stevens-Johnson syndrome, a condition which often leads to toxic epidermal necrosis โ and potential handicap or death โ as a result of taking the drug. The HLA-B*1502 allele most frequently occurs in Han Chinese and Southeast Asian populations and puts individuals at a 1,000-fold increased risk of developing SJS-TEN, he said. In Taiwan, Chen added, approximately 50,000 patients are prescribed carbemazepine annually. Of those 50,000, approximately 115 individuals will develop SJS-TEN โ and, statistically speaking, 106 patients will experience "severe symptoms" associated with the disease, three will experience "complications" resulting in a handicap, and six will die. His team, in collaboration with the Taiwan Drug Relief Foundation, calculated that testing every individual prescribed CBZ for the variant would save the equivalent of $2.97 million.