Talking with a genetic counsellor would be really beneficial to you, Little Crow. Genetic testing is different to a lot of other medical testing in that your results can often give information about other people.
If you go ahead with testing, and are found to carry the same gene as your grandmother, this will also show that your Mum must also be a carrier. SO even though, she doesn't want to know she will find out by default.
This is not a reason for you NOT to get testing, but one of the issues you will have to take into consideration when making your decisions.
Look after yourself when thinking about all these issues, it can be tough.
Monnie24, For those with a family history of genetic disease, with a known gene mutation, genetic testing is often available to family members at no cost.