Going back to autosomal dominance, I’ve found some illustrations of these things called pedigrees which show the heredity of a family. These couple of diagrams below should help explain Huntington’s a little better.
This is the basic key to reading every pedigree ever. This is pretty straightforward so I don’t think I need to talk about this one too much.
Here’s a pedigree that shows the pattern of inheritance of autosomal dominance, like in Huntington’s.
Basically, the thing that shows it’s not a gender-linked disease like colorblindness or hemophilia, is that affected people can pass it on to both sons and daughters. Also, it shows up in every single generation, even though the usual ratios that are associated with Mendelian genetics cannot always come true (autosomal dominance usually affects half of the offspring, and it’s very, very rare that these ratios are found in humans because of the immense complexity of humans.)
Now, with Huntington’s (which I really hope is NOT my life story), the problem is, it’s not expressed until later – I found a graph somewhere that shows the fact that it has a very late onset. You don’t know you have Huntington’s until late…
...way late.
The problem for us is that this is too late to know to not plan for a family – unless we get the test to determine whether I have it. At my age, only about ten or fifteen percent of people affected by Huntington’s show symptoms. There’s where the biggest problem lies – we just don’t know what lies in our genes. My father is getting to the “good” part of the spectrum – at 48, about 70 or 75 percent of people with Huntington’s would show signs of the disease. However, there’s still the chance. But I still have to find out more about Huntington’s before I can make a decision as to whether to go against my father’s wishes. I guess now I should find out about what Huntington’s does to people. This is not going to be pretty.
-By now, fairly depressed thinking about this,Julie
