The somatic mutation landscape of the human body

In this paper, scientists used transcriptome data from over 7,500 tissue samples and 36 tissue types to create a catalog of human somatic mutations. Their catalog contains over 280,000 mutations in total and illustrates a number of tissue-specific mutations.

"Tissues that have more mutations than expected from sequencing depth include those most often exposed to environmental mutagens or with a high cellular turnover like the skin, lung, blood, esophagus mucosa, spleen, liver, and small intestine (Fig. 2a). On the other end of the spectrum are those with low environmental exposure or low cellular turnover such as the brain, adrenal gland, prostate, and several types of muscle—heart, esophagus muscularis, and skeletal muscle."

They also found age was correlated with mutation levels across most tissues. Blood showed the highest association with age and sun-exposed skin had the most significant association with C>T mutations commonly associated with UV radiation. They also found higher levels of mutations in female breast tissue compared to men.

Importantly, they also observed that cancer mutations are enriched in non-diseased tissues, which leads them to say these genes are evolving under positive selection and these mutations increased cellular proliferation even before cancer is observed.

Zac Truesdell - Journal update - Genome Biology - 5
https://genomebiology.biomedcentral.com/articles/10.1186/s13059-019-1919-5