Staveley thought of her son, Alexander, known as Lexi, who has just turned 11: “The most important thing for me is to see Lexi’s kids, to be a grandmother — that wasn’t something I thought would happen.” Staveley’s doctor is Professor Sarah Tabrizi, and I meet them both in Tabrizi’s office at University College London’s Huntington’s Disease Centre in Queen Square, Bloomsbury. The pair seem more like friends than doctor and patient: they are one another’s “hype woman”. But Tabrizi says that while she is “very fond” of all her patients, the relationship remains professional. “She can tell me off!”...