My non-identical twin has HD, what are my chances?

Q. I’m a dizygotic twin, I’m 27, and my brother has Huntington’s Disease (it started around the age of 18). In this situation, am I still at a 50% risk condition of having the gene or, because I’m a dizygotic twin, I have a lower or even null risk of HD?

Bruno, Young Adult, Brazil

A. Hi Bruno,

Thanks for the email. I assume that one of your parents carries the gene?

If you are a dizygotic twin you have the same risk (for carrying the HD gene) as your brother, which is 50%.

With best wishes

Hugh Rickards