Kanahara, N. | Search bioRxiv

bioRxiv2019

Genetic risks of schizophrenia identified in a matched case-control study

BackgroundGenetic association studies of schizophrenia may be confounded by the pathological heterogeneity and multifactorial nature of this disease. We demonstrated previously that combinations of the three functional single nucleotide polymorphisms (SNPs) rs10770141 of tyrosine hydroxylase (TH) gene, rs4680 of catechol-O-methyltransferase (COMT) gene, and rs1800497 of dopamine D2 receptor (DRD2) gene may be associated with schizophrenia onset, and we tested those associations herein. Methods: We conducted a secondary study of 2,542 individuals in age- and sex-matched case-control populations. The schizophrenia diagnosis was based on the DSM-IV. To reduce the influence of confounders (age and sex), we performed a propensity score matching analysis. Genotyping and associative analyses of rs10770141, rs4680, and rs1800497 with schizophrenia were performed. Results: We analyzed 1,271 schizophrenics (male/female: 574/698; age 47.4{+/-}13.9 years) and 1,271 matched controls (male/female: 603/669; age 46.5{+/-}13.4 years). The estimated odds ratios (ORs) were 1.245 (p<0.001) for rs4680, 1.727 (p<0.0001) for rs1800497, and 1.788 (p<0.0001) for rs10770141. Double SNP analyses revealed the ORs of 2.010 (p<0.0001) for the combination of rs4680*rs1800497, 1.871 (p<0.001) for rs1800497*rs10770141, and 1.428 (p=0.068) for rs4680*rs1800497. Among the individuals with any of the three double SNP risk combinations (which accounted for 35.8% of the involved patients), the estimated OR was 2.224 (p<0.0001). Conclusions: In this validation study, the combinations of functional polymorphisms related to dopaminergic genes were associated with the development of schizophrenia. Analyzing combinations of functional polymorphisms with the control of possible confounders may provide new insights for association research.

genetics↗

bioRxiv2018

Genetic combination risk for schizophrenia

Summary ParagraphSchizophrenia is a highly hereditary mental disease1 related to abnormal dopaminergic activities.2,3 To elucidate the mechanisms underlying schizophrenias development, genomic studies have sought to identify the pathogenic genetic polymorphisms. Large-scale genome-wide association studies (GWAS) have reported potential candidate loci that contribute to schizophrenias development.4,5 The risk genetic profiles are not yet established. Here we show that the combination of three functional single nucleotide polymorphisms (SNPs) related to the key factors of dopaminergic signaling can be used to predict the risk of schizophrenias development, though none of the SNPs is known to be associated by itself. These functional SNPs were reported to demonstrate directional influences in their parent gene activity, perhaps characterizing the integrated properties of dopaminergic signaling. Interestingly, the risk combination presented here included the major genotype as well as the minor polymorphisms, suggesting a possible association of unaffected activities of some dopamine-related genes with the disease development. The phenotype speculated based on the allelic status seemed consistent with the conventional pathophysiological hypotheses, although recently developed predictive methods, such as the polygenic risk score, could miss this potent pathogenic role of carrying a normal genotype by evaluating only minor polymorphisms. Our results demonstrate the presence of a subtype in schizophrenia with the favored genetic background related to dopamine signaling. Our findings indicate the possibility that the combinations could characterize integrated biological functions (including neurotransmission) and therefore identify individuals with a disease risk. The biological microenvironment indicated by the functional SNPs could bring an insight to elucidate the pathogenic mechanisms of developing schizophrenia. Furthermore, we believe that our approach will contribute to the development of innovative means to predict disease risks even for other multi-factorial diseases and then, the following preventive medicine.

neuroscience↗