We begin by reviewing the development of the endophenotype construct and update the criteria that endophenotypes should satisfy given the current state of knowledge regarding the genetics of complex traits. Next, we consider how to use molecular genetic methods and analytic techniques to gain insights into the biology of endophenotypes. These recommendations are derived in part from our experience evaluating the molecular genetic basis of 17 endophenotypes that we published as a special issue in Psychophysiology in December 2014. Included in the special issue is an article devoted to molecular genetic methodology (W. G. Iacono, Malone, Vaidyanathan, & Vrieze, 2014a). We recommend this methods article, which was written as a tutorial and included a glossary of technical terms, to our readers who desire better understanding of the molecular and statistical techniques we discuss here. We follow discussion of our special issue with a selective review and critique of electrophysiological endophenotypes in light of our recommended best practices. We conclude by considering future directions for endophenotype research.
