Somatic Mutation Mosaicism Profiled Across Human Development

In PLOS Genetics, researchers at Yonsei University College of Medicine, the Korea Advanced Institute of Science and Technology, and other centers track low-level somatic mosaicism across human development stages and tissue types, distinguishing between mosaic events occurring earlier or later in the developmental process. Using deep exome sequencing, the team profiled somatic mutation patterns in almost 500 organ tissue samples from 190 individuals, uncovering distinct mosaic numbers, allele frequency patterns, and mutational signatures in early or late clone-forming mosaic mutations. "Compared with early clone-forming mutations that showed a clock-like signature across all organs or tissues studied, late clone-forming mutations showed organ, tissue, and cell-type specificity in the mutation counts, [variant allele frequency], and mutational signatures," the authors report, noting that "analysis of brain somatic mutations showed a bimodal occurrence and temporal lobe-specific signature.