So, more depressing stuff about Huntington's. Yay.
The inheritance of Huntington’s was a hard subject for me to research. I might have to break this post up into a few different ones. I don’t know if I can make it through all the way without breaking down… the emotion involved in contemplating that this could possibly happen to me is just too much.
In any case, here it is. There are a bunch of different types of inheritance methods based upon Mendelian genetics. The basic ideas behind Mendelian genetics are simple: It’s an easy cross, the kind of square with the mom and dad on two sides, each donating one characteristic, the Punnett square , as seen below.
But the thing with Huntington’s is, if it’s in your family even once, then it will most likely be passed on. It’s passed on as what’s called an “autosomal dominant.” Let me break this down by word. Autosomal means that it’s not passed on as a sex chromosome (not passed on on either the X or Y chromosome, which are the chromosomes that determine your gender). Dominant means that, among the two alleles that make up who you are, if one of the alleles is a dominant allele, then it will be expressed no matter what the other allele is. Basically a dominant allele masks the expression of other alleles and makes sure it is the only allele expressed. That’s why it’s so dangerous to have Huntington’s – those repeats will be passed on to all your kids, and the kids of your kids, and so on and so on. I’m sorry, but I have to cut this post off. I just can’t keep thinking about this much longer today.
