What have we learned? We now have a sizable body of empirical results relevant to the common “versus” rare variant debate. All common psychiatric disorders with sufficiently large samples have a predominant common-disease/common variant contribution (26–28). Indeed, this is widely seen across human complex diseases like type 2 diabetes mellitus (29), and anthropometric traits like height (30) and body mass (31). Demonstrating a major role of common genetic variation on risk for human complex traits (including psychiatric disorders) is so widely and consistently documented that it is no longer particularly newsworthy.
