Went to hear a talk about how different mutations in the same gene (to do with the semi-rigid network that holds cell nuclei together) can cause a whole range of different diseases: neurological degeneration, heart failure, muscular dystrophies, premature ageing, and problems of fat metabolism. Apparently in one form of the last, patients with inherited mutations are normal until puberty, and then lose most of their subcutaneous fat, instead accumulating body fat in the liver and pancreas. They end up with problems similar to diabetes and chronic heart failure, due to too much fat in places it's not supposed to be as well as too little where it's meant to be.
We heard that the condition is far more readily diagnosed in girls than boys, and indeed that a girl will often be picked up and then her brothers turn out to have the same problem when investigated. Why? Because if a teenaged boy suddenly loses all the fat from his limbs, the uncovered muscles give the appearance of being "cut", and prominent muscles are desirable for teenaged boys. But if a similar process happens to a girl, she panics because her arms and legs are becoming all ugly and muscly, and rushes to the doctor.
The (American) lecturer regarded this as vaguely amusing. But I find it really rather sad, the idea that having visible muscles is such a terrible tragedy for girls. (OK, in this case it is the symptom of a serious disease, but in the early stages there's no reason to think that.) It makes me wonder just how many girls are avoiding doing exercise to make sure their limbs stay soft and unmuscular.