HPS4 and schizophrenia: The major findings of our study were as follows: (1) the HPS4 rs713998 polymorphism was significantly associated with executive function in Japanese patients with schizophrenia, and (2) the polymorphisms (rs9608491 and rs713998) and haplotypic variants (rs9608491-713998 and rs61276843-9608491-713998) in HPS4 were significantly associated with working memory in Japanese healthy controls.