Scientists have found the first robust evidence that people’s genes affect their chances of developing myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS), a mysterious and debilitating illness that has been neglected and dismissed for decades by many in the medical community. To find out more, Madeleine Finlay speaks to science editor Ian Sample and to Nicky Proctor, who has ME and took part in the research. She also hears from Beth Pollack, a research scientist at the Massachusetts Institute of Technology who studies ME/CFS and related conditions, about how scientific understanding of the illness has improved and how scientists are transforming this knowledge into ideas about future treatments