PER3 VNTR variant and susceptibility to smoking status/substance use disorder in a Turkish population

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.

The correlation between PER3 rs2640908 polymorphism and colorectal Cancer in the Japanese population

Background: Colorectal cancer (CRC) is one of the most common cancers in Japan. Many factors influence this cancer, one of which is circadian rhythm disruption. Our research investigated the correlation between singlenucleotide polymorphisms (SNPs) in the Period 3 (PER3) (rs2640908), which is one of the circadian genes, and colorectal cancer in the Japanese population. Methods: The study participants consisted of 121 cases and 197 controls. DNA was extracted from participants' peripheral blood cells, and polymerase chain reaction­restriction fragment length polymorphism analysis (PCRRFLP) was performed to detect genotypes of PER3. Results: Participants with T/T genotype were at lower risk of developing colorectal cancer than participants with C/C genotype (adjusted ORs = 0.32 (95% CI: 0.15­0.63)). When stratified by gender and smoking status, T/T genotype were associated with a decreased susceptibility to cancer in males only (adjusted ORs: 0.23 (95% CI: 0.09­0.59)), T/T genotype were also associated with a decreased susceptibility to cancer among both smokers and non-smokers. Conclusions: A significant association was found between the T allele of PER3 polymorphism and a reduced risk of colorectal cancer, especially in males. Smoking status showed no association with the relationship between PER3 genotype and CRC carcinogenesis (AU)

Association Study between Per3 Gene Polymorphism and Diurnal Preference / 수면정신생리

OBJECTIVE: Diurnal preference is an attribute reflecting whether people are alert and preferring to be active either early or late in the day. It also referred to as chronotype or morningness-eveningness trait. The PER3 genes have been known to influence diurnal preference. In this study, we have investigated the associations between the PER3 gene polymorphisms and diurnal preference in a healthy young population, controlling for the social and environmental confounding factors. METHODS: The participants in this experiment included 299 unrelated medical college students (M=191, F=108), with a mean age of 22.9 years. Diurnal preference was measured by a single administration of the 13-item Composite Scale for Morningness (CSM). Genotyping of the PER3 VNTR (rs57875989) was performed using polymerase chain reaction. A two-tailed alpha of 0.05 was chosen. RESULTS: The mean+/-SD score on the CSM scale for all subjects was 31.90+/-6.39. There was no significant difference in total CSM score between gender groups, although females showed a trend towards higher morningness score. Although PER3 5R/5R showed the tendency towards high CSM scores, there were no significant differences on CSM scores among genotypes and allele status of PER3 VNTR (rs57875989). CONCLUSIONS: We could not confirm that the PER3 VNTR is associated with diurnal preference in a Korean healthy young population. The future studies need to investigate the association between diurnal preference and other polymorphisms of PER3 gene in larger sample of Korean young healthy population.

Do Caucasian and Asian clocks tick differently?

The Period 3 and Clock genes are important components of the mammalian molecular circadian system. Studies have shown association between polymorphisms in these clock genes and circadian phenotypes in different populations. Nevertheless, differences in the pattern of allele frequency and genotyping distribution are systematically observed in studies with different ethnic groups. To investigate and compare the pattern of distribution in a sample of Asian and Caucasian populations living in Brazil, we evaluated two well-studied polymorphisms in the clock genes: a variable number of tandem repeats (VNTR) in PER3 and a single nucleotide polymorphism (SNP) in CLOCK. The aim of this investigation was to search for clues about human evolutionary processes related to circadian rhythms. We selected 109 Asian and 135 Caucasian descendants. The frequencies of the shorter allele (4 repeats) in the PER3 gene and the T allele in the CLOCK gene among Asians (0.86 and 0.84, respectively) were significantly higher than among Caucasians (0.69 and 0.71, respectively). Our results directly confirmed the different distribution of these polymorphisms between the Asian and Caucasian ethnic groups. Given the genetic differences found between groups, two points became evident: first, ethnic variations may have implications for the interpretation of results in circadian rhythm association studies, and second, the question may be raised about which evolutionary conditions shaped these genetic clock variations.