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PNAS Studies on Samoan Population Genetics, Recessive Autism, Metabolite Markers for Frailty

Researchers from the US, New Zealand, and Samoa present findings from an analysis of nearly 1,200 high-coverage Samoan genome sequences, generated for individuals from urban and rural sites on two islands. Based on almost 18 million informative autosomal variants found in 1,197 Samoan genomes sequenced for the "Trans-Omics for Precision Medicine" Project, the team teased out proportions of Papuan, Samoan, and Austronesian ancestry and ancestry related to African, East Asian, and European populations, while retracing past population dynamics and historical gene flow patterns. "These results provide for an increased understanding of Samoan population history and the dynamics that inform it," they report, "and also demonstrate how rapid demographic processes can shape modern genomes."

A Stanford Medical School- and University of California, San Diego-led team describe half a dozen families affected by a recessively inherited form of autism spectrum disorder (ASD). The researchers started by doing exome sequencing on 135 ASD-affected children from consanguineous marriages who participated in the Simons Recessive Autism Cohort. In the process, they uncovered six families with loss-of-function alterations affecting the ACTL6B, a gene coding for a component of a BAF chromatin remodeling complex. That gene, along with other components of the neuronal BAF pathway, appear to be recurrently mutated in recessive ASD, the authors note, which they explore in more detail in human brain organoid and animal models. GenomeWeb has more on this study, here.

Japanese researchers search for blood plasma metabolite markers that coincide with frailty in the elderly, explaining that frail elderly individuals "commonly manifest complex clinical symptoms, including cognitive dysfunction, hypomobility, and impaired daily activity, the metabolic basis of which remains poorly understood." To explore these metabolic features, the team used liquid chromatography-mass spectrometry-based analyses to assess 131 metabolites in blood samples from 19 elderly individuals tested for cognitive function, motor ability, and other features on a frailty scoring scale, highlighting a handful of candidate markers for frailty, cognition problems, and/or reduced mobility. "These overlapping sets of markers included metabolites related to antioxidation, muscle or nitrogen metabolism, and amino acids," they note, "most of which are decreased in frail elderly people."