In Science this week, a group of British investigators publishes a study showing that genetic mutations associated with cancer are common in esophageal epithelial tissue of older, healthy individuals. The investigators sequenced normal esophageal epithelium from nine donors aged 20 to 75 years and find strong positive selection of clones carrying mutations in 14 cancer genes. Notably, in middle-aged and elderly donors, cancer-associated mutations were found in much of the epithelium — including the cancer-driver mutation NOTCH1. "Better understanding of the extent of somatic mutation and selection across tissues, in health and disease, promises to provide insights into the origins of cancer and aging," the team concludes. GenomeWeb has more on this, here.
And in Science Advances, an international research team uses population genomic and phylogeographic analyses to show that human migration out of Europe drove the spread of today's dominant tuberculosis strain — called L4 — while drug resistance developed independently and locally. By studying 1669 Mycobacterium tuberculosis L4 genomes, the investigators show "an intimate temporal relationship between European colonial expansion into Africa and the Americas and the spread of L4 tuberculosis." Meanwhile, in the age of antibiotics, antimicrobial-conferring mutations overwhelmingly emerged on the nation level, with minimal cross-border transmission of resistance. The findings, the scientists write, suggests that containment efforts at the level of individual countries could be successful. GenomeWeb also covers this, here.