My grandfather on my father's side was diagnosed with als at 56 and died months later. he's the only one who's had it as far as i know. my father is now almost 60 with no symptoms of als. what are the chances that familial als runs in my family?

Difficult to assess but one can now be tested by drawing blood and tested for the gene. If you want to know. Discuss with family Dr.

ALS is relatively uncommon, about 5-6 cases per 100,000, and familial ALS is but 10% of these. Therefore, rather unlikely there is any genetic component. Thus, based on actual statistics, it is unlikely, that FALS "runs in...family".