ANKK1 and schizophrenia: To date, there are inconsistent results from several association studies of ANKK1 polymorphism with schizophrenia and its clinical phenotypes (Alfimova et al., 2017, 2018; Arab & Elhawary, 2015; Eisenstein et al., 2017; Nkam et al., 2017; Parsons et al., 2007; Ponce et al., 2009; Wishart et al., 2011; Yao, Pan, Ding, Pang, & Wang, 2015; Zhang et al., 2014).