[ckayatek]

Known makers make up less than half of known hereditary cases of ALS. That is in families with a history of ALS, only about 30-40% cases have been tracked down to mutations in a single gene. SOD1 mutations are the most common form of familial ALS but like I said, if you had a novel mutation, meaning one that hadn't been observed before, you'd really have no idea. Also if you have one of many previously identified mutations that have been observed in only a few or even a single patient, you still couldn't be sure you'd get ALS.