The October 2018 Editor's Choice article is "Somatic Mutation Load and Spectra: A Record of DNA Damage and Repair in Healthy Human Cells" (https://onlinelibrary.wiley.com/doi/10.1002/em.22215) by Natalie Saini and Dmitry A. Gordenin.
In their Editor’s Choice article, Saini and Gordenin summarized literature on next generation sequencing (NGS) and how it is being used to understand the nature and magnitude of the mutational load in tissues of cancer-free individuals. Specifically, NGS approaches amenable to the analysis of somatic variation were described, including single cell sequencing, the use of barcoding to distinguish true mutants from sequencing errors, and the sequencing of clonally-expanded cells. The merits of different base calling software were discussed, as were strategies to increase the accuracy of NGS base calling. In addition, Saini and Gordenin identified “mutational signatures” and the molecular mechanisms that underlie the different signatures.
Beyond the technical discussion of NGS, this article identifies diseases associated with somatic mutation and genetic mosaicism (e.g., autism spectrum disorders). Studies of healthy human tissues and environmentally exposed tissues were reviewed (e.g., UV-exposed skin). These observations were integrated with a discussion of available information on human somatic mutation rates. Understanding the extent of mutation in normal-appearing human tissues (mutational load) is a timely topic. The authors conclude that “similar to cancer genomes, the mutation loads and spectra across the body and in different cell types were found to be dependent on the proliferative ability of the cells, their DNA repair capacity and the endogenous or exogenous DNA damaging agents the cells can encounter.” Thus, this Editor’s Choice article is an important scholarly contribution to the field of human genetics that will be of interest to researchers and clinicians alike. Environ. Mol. Mutagen. 59:672-686, 2018.