Over the past 10 years, I have worked with a doctor who is researching Huntington's Disease (HD). This terrible malady causes the degradation and eventual failure of neurons in brain cells and almost always ends in death at a fairly early age.
He contacted me because I had traced the descendancy and lineage of my great aunt and her husband. His first contact asked if I had ever observed or exhibited a list of symptoms that he included in his letter. I hadn't seen them in our branch of the family but did note that the profile of early deaths and other issues were frequently found in my great aunts branch of our family.
This confirmed his suspicions and I was able to put him in contact with several of my extended cousins from that branch. They knew that some members of the family had HD but had no idea of its extent and impact on the entire branch. In fact, it has devastated every family unit in that branch. Now that they know how it affects personalities and actions, they better understand why certain events occurred in the lives of some family members.
The HD gene was introduced into the family by the husband of my great aunt and thus none of the siblings of my great aunt have the problem.
Thinking about the implications of a 'bad' gene in my own genetic makeup, I started to document the cause of death of my own ancestors and their families. The results weren't a total surprise, but the problem was much more prevalent than I would have ever dreamed. My father's side of the family predominately died of heart diseases and / or heart attacks. My mother's side of the family either lived long healthy lives or had heart and nervous problems.
When I created a graphical descendancy chart for my 2nd great grandparents and colored each box showing the cause of death, it was instantly apparent that my chance of dying with heart related problems is very high.
Scientists and other researchers have used genealogical data to track the proclivity of diseases in their patients for a number of years. With the now fairly common use of DNA mapping, science is able to predict inherited genetic weaknesses with surprising precision.
If you haven't taken the time to research and study the cause of death or illnesses in your own ancestral families, you'll probably want to do it soon. The knowledge could help save your life as you use it to work with your physician to find a lifestyle and preventative treatments that will at least partially mitigate your own genetic weaknesses.