Genetic Interaction Network And Methodologies To Infer These

Question

[rich.a.schaefer]

First of all Im having a question about gene interaction networks. How exactly do they differ from gene regulatory networks? I mean its clear that epistasis interaction are a common theme in them. But what does that mean? I mean epistatic effects are in the end effect protein interactions, right? For example the BioGRID database distingushes between physical and genetic interactions. Whats the difference.

Second question. What are the current methodologies to infer genetic interactions. It is possible to infer genetic interactions from expression data alone?`And what are the current approaches? Mostly in Genetical Genomics studies?

Thanks