Is there an authoritative database to find which genes (SNPs) are already known for which disease? With no limit on the study method. Thanks! (New to biology)
Have a look at [DisGeNET][1]. It is a very well done and well supported database that aggregates and curates information from other sources. We are happy to use it in Open PHACTS (which also offers another way to access it).

 [1]: http://www.disgenet.org