Abstract Background Substance use and smoking exert devastating impact on sleep, especially hindering the ease of falling asleep, compromising the sleep maintenance, and distorting the sleep cycles. PERIOD genes are believed to play a role in individual differences in sleep timing by influencing circadian. Objective The aim of this study was to ascertain whether Per3 VNTR variant affects suspectibility of individuals to substance use disorder (SUD) and smoking status in a Turkish population. Methods A total of 549 subjects, including 212 SUD patients, 160 smoker, and 177 healthy controls, matched by ethnicity, age, and gender, were recruited in a case-control study. Genotyping of Per3 variant was performed using PCR method. Results When the SUD, smoker groups and controls were compared in terms of 5R/5R, 5R/4R, 4R/4R genotypes, no significant difference was observed. Besides, allele frequencies of Per3 VNTR were similar among the groups. Discussion Our data indicate that Per3 VNTR variant is not associated with the risk of SUD and smoking status in our population.

Abstract Objectives Schizophrenia (Sch) is a severe and chronic mental illness. Smoking prevalence is higher in patients with Sch than general population. We aimed to investigate the effects of MAOB gene A644G variant on nicotine dependence (ND) and Sch+ND risk in Turkish population and to evaluate by bioinformatic analysis. Methods Present study included 161 individuals with ND, 223 patients with Sch+ND, and 96 non-smoker controls. MAOB A644G variant was analyzed using PCR-RFLP method. As the MAOB gene is located on the X chromosome, each gender was analysed separately. Results The total distributions of AA, AG and GG genotypes of MAOB gene A644G were 44.7%, 22.4% and 32.9% in the ND group, 45.3%, 25.1% and 29.6% in the Sch+ND group and, 44.8, 22.9% and 32.3% in non-smoker controls. No significant differences were observed between groups for the MAOB A644G genotype and allele frequencies when female group compared to male group (p > 0.05). Examination of disease associations of SNPs from each miRNA gene region in GWAS databases yielded results for aging, bipolar disorder, autoimmune, and neurological diseases. Discussion Our results indicate that the MAOB gene A644G variant is not associated with ND and/or Sch susceptibility in the Turkish population.

Abstract Background: Oxidative stress induced DNA damage has been assumed to contribute to the etiopathogenesis of schizophrenia (Sch). Smoking prevalence was more common in patients with Sch. The X-ray repair cross-complementation group 4 (XRCC4) gene plays an important role in the repair of DNA double-strand breaks. Objective: The purpose of this study was to investigate whether XRCC4 rs6869366 polymorphism has a relationship both in nicotine dependence (ND) and Sch+ND risk. Methods: One hundred and four patients with Sch+ND, 133 subjects with ND only and 70 healthy controls were enrolled in the study. XRCC4 rs6869366 polymorphism was analyzed using PCR-RFLP assay. Results: The frequency of XRCC4 rs6869366 GG genotype was more common in the ND and Sch+ND group than controls (p = 0.001 and p = 0.001, respectively). XRCC4 rs6869366 TT genotype was lower in both ND and Sch+ND group compared to controls (p = 0.001 and p = 0.001, respectively). Also, XRCC4 rs6869366 G allele was higher in Sch+ND group than controls (p = 0.001) while XRCC4 rs6869366 T allele was lower in ND group than healthy controls (p=0.001). XRCC4 rs6869366 GT genotype was lower in ND group than control group (p = 0.003). Discussion: These results suggested that the XRCC4 rs6869366 polymorphism G related genotype/allele was associated with susceptibility to both ND and Sch+ND in a Turkish population.