Somatic genomics as a discovery engine for biomedicine

Somatic mutations, or genetic changes occurring in cells after conception, are widespread in healthy tissues but are conventionally viewed as signs of pre-cancer or simply a consequence of aging. However, an emerging body of work has shown that somatic mutations can drive or protect against disease, which could inspire novel therapeutic strategies. The unexpected depth of genetic diversity within individuals also provides a massive substrate for discovering mutant genes selected for by disease. For instance, mutant hematopoietic cells can exacerbate inflammatory disease, and mutant hepatocytes can protect against liver disease. This suggests that somatic mutations, whether maladaptive or beneficial, could provide crucial insights into disease mechanisms, history, and reversal strategies. Somatic genetics offers a powerful, complementary approach to traditional germline genetics, which has had an enormous impact on biomedicine and drug development. This review explores the factors that shape the landscape of somatic mosaicism and discusses somatic mutations that cause or protect from disease. We highlight how somatic mutations are becoming a key discovery engine for disease genetics, moving rapidly toward drug target identification and clinical translation.