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This Week in PNAS: Sep 13, 2016

In the early, online edition of the Proceedings of the National Academy of Sciences, a team led by investigators from the Catholic University of Korea describes recurrent mutations in the serine/threonine kinase enzyme-coding gene AKT1 in a benign lung tumor condition called pulmonary sclerosing hemangioma. Starting with exome sequencing on pulmonary sclerosing hemangioma and matched normal samples from 44 individuals, the team identified AKT1 mutations in more than 40 percent of tumors — results they confirmed through testing on two dozen more pulmonary sclerosing hemangiomas. A smaller proportion of tumors had recurrent mutations in the beta-catenin gene, and non-recurrent alterations turned up across many genes implicated in cancer.

Investigators from Iowa State University, the National University of Singapore, and the Genome Institute of Singapore search for sources of hyper-virulence in the foodborne and animal pathogen Campylobacter jejuni. Using a directed evolution approach, the team did whole-genome sequencing on virulent strains — known for escaping the intestinal tract to produce system-wide infection and spontaneous abortion in pregnant ruminant animals — and less virulent strains, all grown in a guinea pig model. Through sequencing and comparison of almost 100 C. jejuni isolates, the study's authors narrowed in on point mutations in the outer membrane protein-coding gene porA that appeared to boost virulence in the bug.

Finally, an international team introduces a neurological syndrome that appears to be caused by autosomal recessive mutations in the glutamate pyruvate transaminase 2 enzyme-coding gene GPT2. The researchers used a combination of linkage mapping and exome sequencing to search for suspicious mutations in two large families that contained individuals with features such as microcephaly, intellectual disability, tremors, and progressive motor problems. In affected individuals, they tracked down loss-of-function GPT2 mutations, prompting follow-up studies of mice missing the gene. Without the gene, which is normally expressed more highly after birth, the mice had both muted brain growth and shifts in brain metabolite patterns.