Risk of tay sachs disease?

My cousin had her baby 4 years ago and the child had Tay Sachs, i have seen this baby getting worse and worse and im terrified that one day when i have children it will turn out the same, im only 18 now so not thinking about starting a family and i will get tested before i have children.
I want to know now without the test how big the risk would be that someone else in the family is also a carrier of the gene?
I know the rate is rising in Irish-Americans and my boyfriend is Irish-American and i am Irish.
I know the information about the disease, statistics etc but so far haven't found any information about the risk of other relatives being carriers, so if anyone knows any information relevant to this, id be very grateful.
Thanks =)

I am going to get tested before i have children which will be a long time off.
Im just looking for information about how likely it is for a relative of someone who is a carrier of tay sachs to also have the same carrier gene.

I can quote statistics all day long, and you still won't know anything. You should be tested, as should your boyfriend if he is the person with whom you expect to have children. Once you have the facts, you can quit worrying, and start to make intelligent plans about child-bearing.

I also have a genetic disorder which became known at the birth of my first child. For my husband and I, we had our particular syndrome verified via genetic testing. We are encouraging his brother and his wife to get the same test done before having children....I don't see why you couldn't either. However, if he is still just a boyfriend, they may balk at the idea of genetic testing. You can always try though.