There is a growing feeling that genetic testing will offer major changes in medicine, and that both diagnosis and drugs will be tailor made to each of us based on detailed analysis of our DNA some time in the next few years.
While appealing, this unfortunately is an extremely unlikely scenario. It turns out that only a few, relatively rare, diseases are due to changes in single gene function. Probably the most common is sickle cell anemia, and there are a handful of others. There are, for...

