As a heuristic model, one can consider a cascade from the studied phenotypic syndrome to the genes, with different levels of analysis: syndrome-mediating dimension/trait; self-report measure/clinical interview; laboratory behavioral task performance; cognitive task performance; psychophysiological task performance; functional, structural and neurochemical imaging; postmortem neurochemistry, cell structure, mRNA expression; genotype.19 These complementary approaches, when used in the identification of endophenotypes for SB may provide convergent validity for the most promising endophenotypes,17, 19, 20, 21 while noting that predicting rare events such as SB (especially completed suicides) adds to the difficulties of such research.22, 23
