GENETIC

  MY AUNT DIED LAST JUNE FROM ALS, HER SISTER, MY OTHER AUNT DIED LAST NIGHT FROM ALS.  THIS DISEASE CAME OUT OF    NO WHERE ?  I HAVE 3 OTHER AUNTS STILL LIVING PLUS MY MOM, HOW WORRIED SHOULD I BE? THEY RANGE FROM 65 TO 86. I READ SOMETHING ABOUT A GENE OR CHROMOSOME, BUT DID NOT UNDERSTAND.  CAN ANYBODY HELP ?    
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I am sorry to hear about your aunts.
In general, ALS is not a genetic disease, but there is a genetic form.
The last time I reviewed the numbers, about 10% of cases of ALS are familial - that is, hereditary. That means 90% are not. If you have two relatives who each had ALS, that suggests possibly a genetic form but that doesn't mean it is written in stone.
Of the 10% of ALS which runs in families, about 10% of those cases (total about 1% of all ALS) is related to a specific defective enzyme. That is the copper-zinc superoxide dismutase (Cu-Zn SOD), which you may have seen because there is a lot of research interest.
For specific questions, you may want to consult with an ALS expert. We have such an expert here at CCF. You may call 800 223-2273 and ask for neurology appointments to arrange an evaluation, if you have any symptoms you are concerned about.
CCF MD mdf.