RPP21 and schizophrenia: This SNP is localized between NOTCH4 and BTNL, both of which have been implicated in SZ susceptibility.52, 53 An interaction of NOTCH4 with cognition and SZ was also reported in another study.54 rs3130375, the most significant SNP in an international schizophrenia consortium (ISC) study (comprised of multiple European GWASs) is associated with accuracy in the working memory domain and is localized to RPP21, which is involved in processing of 5′ leader sequences of precursor t-RNA.