age of testing should be 18 or over. As to whether you should be tested when you turn 18 depends on whether or not you would like to find out your gene status. Some people like to know but a large amount of people do not get tested. So it is a very personal choice. If you would like to speak to someone about it you can contact your local Huntington's association or if you want to connect with others in similar circumstances add Greg Chaine (HWA) on Facebook and send a message asking to be added to the National HD Alliance for Young People. I hope this is helpful. My brother has CAG of 42. My wife acquired Mystenia Gravis after my son was born. If my son has HD could it cause Mystenia Gravis in my wife? - Terry (48) Terry, Myaesthenia gravis is completely unrelated to HD. Your son's gene status is totally  unrelated to your wife getting myaesthenia gravis. It was just a fluke that she got it and that her & your son is at some risk of inheriting the HD gene. If your brother has HD & you have not had a gene test then your risk of carrying the HD gene, even if you do not have symptoms, is 1 in 2 (i.e. a 50:50 chance). Your son's risk of carrying the gene is 1 in 4. If your brother has HD & you have been shown to be gene negative, then your