Genomics, 2014). In fact, neurodevelopmental disorders like schizophrenia, which only a few decades ago were thought to be caused primarily by the home rearing environment, are not all that different in their genetic architecture from complex medical diseases like coronary heart disease or type 2 diabetes (Visscher, Brown, McCarthy, & Yang, 2012). The small effect of any individual common genetic variant is undetectable without an adequately powered design. A longstanding hope is that individual genetic effects on endophenotypes will be larger, thereby increasing power to detect genetic variants related to disease and psychiatric disorders. However, relatively few reports put endophenotypes to the ultimate test, evaluating whether in fact an endophenotype can be used to identify molecular genetic variants associated with psychopathology. Those that exist have been largely restricted to candidate gene investigations or small sample reports that, if they have generated positive results, have not been verified. Our recent work, which constitutes the most comprehensive large sample molecular genetic investigation of electrophysiological endophenotypes undertaken to date (described in detail below, see W. G. Iacono, 2014a), provides little basis for optimism that endophenotypes will live up to the hope that they will lead to breakthroughs in the identification of psychopathology relevant
