Genomics. What does that tell us??

http://tx.english-ch.com/teacher/bien/others/family-genomics-links-dna-to-disease/

There are now 93 regions of the human genome that have been associated with schizophrenia...

"You might say, what is this telling us?
The answer is, we don't always know, but I'll tell you one thing-- four of those genes encode different subunits of exactly the same multi-protein complex that is a certain calcium channel in neurons.
That's not an accident.
That tells you in a way you would have never guessed.
And only genetics can tell you that particular L-type calcium channel-- four subunits there-- carry mutations, all of which are associated." 7.00x Intro to Biology- The Secret of Life

"It is up to about 47 genes that have been associated with hereditary risk of breast cancer. Some of them have weak effects.
They explain, oh, I don't know, about a 1/6 of the inheritance.
There are a bunch of strong mutations-- Mendelian-like forms-- they explain about a 1/6 so far. Together, they might explain about 1/3 so far. It's by no means done. But this is what's going on."

"A polygenic disease is a disease that is associated with mutations in more than one gene. For many polygenic diseases, the mutations associated with the disease do not directly result in a disease phenotype but are, instead, correlated with an increase in the risk of having the disease phenotype. " 

Eric Lander PhD, "Intro to Biology, the Secret of Life", MOOC MITx , June 2013.