Comment by dekhn
4 days ago
You were asking about individual mutations, like SNPs or small indels?
Very few diseases are caused by individual mutations like that (typically only monogenic Mendelian). Individual mutations typically cause an increased propensity, or severity, rather than being the sole or root cause of a disease.
I work with monogenic diseases, where a single mutation (or a pair in the same gene for recessive conditions) does cause disease. There's a lot of them. Your statement isn't true for these.
You're talking about polygenic traits. That's a different ball game entirely.
Sorry, I should have said: the preponderance of people with disease suffer from (a small number of) polygenic trait diseases, while if you sum up all the monogenic diseases, it's a smaller number of people with disease by far. You're correct that there are many monogenic diseases but the vast majority of them are extremely rare.
In short, if you solve a monogenic disease you help maybe 20-30 million worldwide (and then you have to solve other ones), if you solve CVD,type 2 diabets, hypertension- each of those is 500+M people. So in general, we would expect to have more impact with polygenic, although they tend to be far harder to treat because of the complexity.