The disorder — fragile X-associated tremor-ataxia syndrome — causes tremors, balance problems and dementia that become progressively more severe with age.

This is the same Fragile X, as in Fragile X syndrome that causes retardation. (though in this case, according to the article it's a "proto-mutation" - I'm going to guess that implies the mutated segment is repeated more times than is correct, but not so much as to cause full-on Fragile X syndrome) This would therefore mostly be an issue for men in families with a history of Fragile X syndrome.

Women are at significantly less risk because they have a 2nd X chromosome, which would usually be free of mutation. Though it should be possible for a woman to be affected if both her X chromosomes had Fragile X mutations.

Anyway, a new neurodegenerative disease. You don't hear that every day.