A lot of people seem to click on this one looking for tuberous sclerosis or tuberculosis, so here’s a little information:
Tuberculosis is a highly communicable illness known in the 1800s as ‘consumption’ because it causes wasting in the end stages. Modern medicine has done a good job of eradicating it…and of creating super-resistant strains that are also highly communicable. At present, the main solution is to isolate the sufferer. (Which probably makes their suffering worse.)
Tuberous sclerosis is a genetic disorder that causes function-disrupting ‘tubers’ to form in the brain…somewhat like MS, but not quite: it doesn’t follow the relapsing-remitting patterns (I think). Also ‘House, M.D.’ tells me that the tubers can form anywhere.
And you should really double check this information, as it’s been a while since I had to know this stuff.