Science 364, 970 (2019)

Healthy adult human tissues are made up of multiple genetic clones.

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Mutations in somatic tissues can lead to diseases such as cancer, but the extent to which these mutations occur without incidence of disease is not known.

A group of researchers in the United States developed a pipeline for identifying somatic mutations by comparing the identifiable RNA mutations with those in DNA from the same tissue. By analyzing publicly available data, the authors find that adult tissues are made up of multiple subclones, the number of which varies between tissues.

Factors that affect the number of subclones within the tissues include environmental exposure and cellular division rate. authors also found some of the clones were selected for, suggestive of the early stages of carcinogenesis.