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Background: Metabolic risk factors represent a major cause of increased coronary heart disease morbidity and mortality among psychosis patients. Although antipsychotic medication may lead to hyperglycemia, an association to severe mental illness was established before the introduction of antipsychotics. Methods: We investigated the association between metabolic risk genes and elevated fasting glucose level in patients with schizophrenia spectrum disorder. We applied two association models; (i) case-case where psychosis patients with elevated fasting glucose level (≥5.6 mmol/l) or diagnosed diabetes (n=263) were compared to patients with normal glucose level (n=389), and (ii) case-control model where psychosis patients with elevated fasting glucose level were compared to population-derived controls (n=494). Association analyses were adjusted for age, sex, smoking, family history of diabetes, and waist circumference. (iii) We also investigated whether metabolic genes were associated with schizophrenia spectrum disorder independent of fasting glucose. Results: No differences between schizophrenia spectrum diagnoses regarding genetic associations with increased fasting glucose were detected. In a case-case model, a genetic variant in IGF2BP2 was associated with elevated fasting glucose level among persons with schizophrenia spectrum disorder. In a case-control model associations were found with genetic variants in the NOTCH2, THADA, WFS1, P2RX7, and MNTR1B. A genetic variant in PPARD was nominally associated with schizophrenia spectrum disorder independent of glucose level. Conclusion: Our findings indicate that common metabolic polymorphisms associated with elevated fasting glucose among schizophrenia spectrum disorder patients may at least partially be explained by increased vulnerability in schizophrenia spectrum disorders for genes associate with elevated fasting glucose in the population.

Objective: Recent genetic studies have demonstrated that Single Nucleotide Polymorphism (SNP) rs35767(C/T) in the IGF1 gene promoter is associated with insulin resistance and serum IGF-I levels and thereby implicated that IGF1 has genetic effect in Type 2 Diabetes (T2D). The present study aimed to investigate the alteration of DNA methylation levels of the IGF1 gene in T2D. Subjects and methods: A total of 688 Swedish men with Normal Glucose Tolerance (NGT) or T2D were selected from Stockholm Diabetes Prevention Program. DNA methylation levels at rs35767 SNP-CpG site and other three CpG sites (P1-P3) in the IGF1 gene promoter region were analyzed with PyroMark Assays and bisulfite pyrosequencing. Fasting serum IGF-I levels were measured with an in-house radio-immunoassay. Results: DNA methylation levels at CpG site P3 of the IGF1 gene promoter were increased in T2D patients compared with NGT subjects (84.8% vs. 74.2%, P

Objective: RGS9 is a member of the family of Regulators of G-Protein Signaling (RGS) proteins defined by the presence of an RGS domain which can accelerate the GTPase-activity of G protein Gα subunits. An insertion/deletion (I/D) polymorphism of the nucleotide sequence TTTCT (rs3215227) has been identified in the human RGS9 gene, which matches the consensus high affinity binding motif for the ubiquitously expressed RNA binding Polypyrimidine Tract Binding Protein (PTB). In this study, we evaluate the genetic association and functional relevance of this polymorphism in type 2 diabetes and obesity. Subjects and methods: We genotyped a larger population of 9272 Chinese and Malaysian individuals for the RGS9 I/D polymorphism using Taq Man allelic discrimination protocols. We found that the D allele of the RGS9 polymorphism was associated with a decreased prevalence of obesity in women (P=0.003, OR=0.753 95%CI 0.625-0.906) and girls (P=0.002, OR=0.604 95%CI 0.437-0.835). The association was moderate in boys (P=0.038, OR=0.724 95%CI 0.533-0.983) and not significant in men. Furthermore, we found that the transcript deletion variant exhibited a 10-fold reduction in PTB binding in vitro and that the splicing of the deletion variant was less affected by PTB co-expression. Conclusions: We provide genetic and biochemical data to support a genetic role of RGS9 in obesity but unlikely in T2D. The RGS9 I/D polymorphism influence the post-transcriptional processing of the gene through an altered affinity for the splicing factor PTB and are associated with obesity.