Numerous linkage and association studies by our group and others have implicated DPYSL2 at 8p21.2 in schizophrenia. Here we explore DPYSL2 for functional variation that underlies these associations. We sequenced all 14 exons of DPYSL2 as well as 27 conserved noncoding regions at the locus in 137 cases and 151 controls. We identified 120 variants, eight of which we genotyped in an additional 729 cases and 1542 controls. Several were significantly associated with schizophrenia, including a three single-nucleotide polymorphism (SNP) haplotype in the proximal promoter, two SNPs in intron 1, and a polymorphic dinucleotide repeat in the 5′-untranslated region that alters sequences predicted to be involved in translational regulation by mammalian target of rapamycin signaling. The 3-SNP promoter haplotype and the sequence surrounding one of the intron 1 SNPs direct tissue-specific expression in the nervous systems of Zebrafish in a pattern consistent with the two endogenous dpysl2 paralogs. In addition, two SNP haplotypes over the coding exons and 3′ end of DPYSL2 showed association with opposing sex-specific risks. These data suggest that these polymorphic, schizophrenia-associated sequences function as regulatory elements for DPYSL2 expression. In transient transfection assays, the high risk allele of the polymorphic dinucleotide repeat diminished reporter expression by 3- to 4-fold. Both the high- and low-risk alleles respond to allosteric mTOR inhibition by rapamycin until, at high drug levels, allelic differences are eliminated. Our results suggest that reduced transcription and mTOR-regulated translation of certain DPYSL2 isoforms increase the risk for schizophrenia.

We previously reported a schizophrenia-associated polymorphic CT di-nucleotide repeat (DNR) at the 5′-untranslated repeat (UTR) of DPYSL2, which responds to mammalian target of Rapamycin (mTOR) signaling with allelic differences in reporter assays. Now using microarray analysis, we show that the DNR alleles interact differentially with specific proteins, including the mTOR-related protein HuD/ELAVL4. We confirm the differential binding to HuD and other known mTOR effectors by electrophoretic mobility shift assays. We edit HEK293 cells by CRISPR/Cas9 to carry the schizophrenia risk variant (13DNR) and observe a significant reduction of the corresponding CRMP2 isoform. These edited cells confirm the response to mTOR inhibitors and show a twofold shortening of the cellular projections. Transcriptome analysis of these modified cells by RNA-seq shows changes in 12.7% of expressed transcripts at a false discovery rate of 0.05. These transcripts are enriched in immunity-related genes, overlap significantly with those modified by the schizophrenia-associated gene, ZNF804A, and have a reverse expression signature from that seen with antipsychotic drugs. Our results support the functional importance of the DPYSL2 DNR and a role for mTOR signaling in schizophrenia.

Objectives: Genome-Wide Association Studies (GWAS) of Schizophrenia (SCZ) have provided new biological insights; however, most cohorts are of European ancestry. As a result, derived polygenic risk scores (PRS) show decreased predictive power when applied to populations of different ancestries. We aimed to assess the feasibility of a large-scale data collection in Hanoi, Vietnam, contribute to international efforts to diversify ancestry in SCZ genetic research and examine the transferability of SCZ-PRS to individuals of Vietnamese Kinh ancestry. Methods:In a pilot study, 368 individuals (including 190 SCZ cases) were recruited at the Hanoi Medical University's associated psychiatric hospitals and outpatient facilities. Data collection included sociodemographic data, baseline clinical data, clinical interviews assessing symptom severity and genome-wide SNP genotyping. SCZ-PRS were generated using different training data sets: i) European, ii) East-Asian and iii) trans-ancestry GWAS summary statistics from the latest SCZ GWAS meta-analysis.Results: SCZ-PRS significantly predicted case status in Vietnamese individuals using mixedancestry (R 2 liability=4.9%, p=6.83*10 -8 ), East-Asian (R 2 liability=4.5%, p=2.73*10 -7 ) and European (R 2 liability=3.8%, p = 1.79*10 -6 ) discovery samples. Discussion: Our results corroborate previous findings of reduced PRS predictive power across populations, highlighting the importance of ancestral diversity in GWA studies.