It says the disease has run in the family for 6 generations. This kind of mutation shouldn't exist.. in nature they wouldn't survive two days, but in our modern society they have for 150 years or so..
http://www.guba.com/flash/300001313...9451:2bdd5d4711b070a8eb5836a6227176f42f68a297
http://www.guba.com/flash/300001313...9451:2bdd5d4711b070a8eb5836a6227176f42f68a297