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This Week in PNAS: Apr 4, 2017

In the early, online edition of the Proceedings of the National Academy of Sciences, a team from Australia and China reports on a high-altitude adaptation signature identified in individuals from Tibet. The researchers used a SNP arrays and an exome-focused array to profile genetic patterns in 3,008 individuals from two sites on the Tibetan Plateau. Compared with genotyping profiles in nearly 7,300 East Asian, non-Tibetan individuals, they tracked down variants at nine loci that showed signs of selection in the Tibetans, including blood-related loci near the EPAS1 and MTHFR. The analysis also offered a glimpse at the genetic relationships between Tibetans and individuals from Han Chinese and other populations in China.

A Massachusetts Institute of Technology-led team tracks the mutations that accumulate in liver samples from mice exposed to aflatoxin B1, a food spoilage-related fungal toxin that has been linked to hepatocellular carcinoma risk. Using duplex sequencing, the researchers profiled mutation patterns in liver samples from male mice exposed to aflatoxin B1 during a process that prompted hepatocellular carcinoma development over more than a year. Based on mutational spectra in tumor and neighboring normal liver tissue from the mice, the authors note that both types of aflatoxin B1-exposed liver samples share guanine to thymine base changes. "The discovery of caner-associated exposure mutational spectra that appear long before the signs of malignancy will benefit the cancer epidemiology and prevention communities," they write. GenomeWeb has more on this study, here.

Another PNAS study points to a role for de novo mutations in early-onset high myopia (EOHM), an eye disease that is particularly common in East Asia. For that analysis, researchers from the State Key Laboratory of Ophthalmology, Optometry, and Vision Science and other centers in China and the US did exome sequencing on 18 individuals with EOHM and their unaffected parents. Along with rare inherited mutations in genes previously implicated in eye-related processes, their analyses revealed a slight uptick in de novo mutations in affected children. The team went on to characterize one of the candidate genes, BSG, through targeted sequencing in more than 1,000 more high myopia patients and mutant mouse model experiments.