HD is a dominant trait. My brother-in-law died of it as well as his father. His brother is also has it. There are many in our area with HD.
Onset at around age 40 is bad too, because you've usually already had your kids and passed it on to the next generation.
My sympathies to your family. Are most of the younger folks in your area taking the new genetic test, or are they just letting the chips fall where they may?