This new study has caused a stir, not so much for the findings themselves as for the approach that homed in on more severe cases. Researchers have tried and failed before to find genes linked to depression, but now someone has done it, despite using a smaller sample (5,300 discovery phase, 3,000 validation phase) than previous unsuccessful attempts. Sparse whole-genome sequencing identifies two loci for major depressive disorder : Nature The researchers recruited patients in China, reasoning that as depression is under-diagnosed there, only the more severe cases will be diagnosed (a view their data supported), and they also restricted the cohort to patients that were ethnically Han Chinese. Focusing on more severe cases increases the 'signal' strength and the ethnic focus reduces variablility ('noise') giving a stronger signal-to-noise ratio, making discoveries easier. (Focusing on severe cases may well also reduce noise/variability.) An accompanying Nature News article highlighted the potential of this approach. First robust genetic links to depression emerge : Nature News & Comment Maybe a similar approach would pay off in mecfs. And I sincerely hope researchers will be undertaking a serious search for a genetic links in mecfs in very large cohorts sooner rather than later.