Association of the Serotonin 2A Receptor rs6311 Polymorphism with Diurnal Preference in Koreans

Genetic polymorphism in HTR2A rs6313 is associated with internet addiction disorder

Introduction

Internet addiction disorder (IAD) has grown into public health concern of global proportions. Previous studies have indicated that individuals with IAD may exhibit altered levels of serotonin and dopamine, which are known to play crucial roles in depression, anxiety, impulsivity, and addiction. Therefore, polymorphisms in the receptors that mediate the effects of serotonin and dopamine and affect their functional states as well as their activities are suspect. In this study, we aimed to investigate the association between IAD and rs6313 (T102C) polymorphism in the serotonin 2A receptor (5-HT2A) gene, (HTR2A).

Methods

Twenty patients with IAD and twenty healthy controls (HCs) were included in this study. Young's Internet Addiction Test (IAT), Self-Rating Anxiety Scale, Self-Rating Depression Scale, Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Barratt Impulse Scale, Pittsburgh Sleep Quality Index (PSQI), and Social Support Rating Scale (SSRS) were used to assess the severity of internet addiction, mental status, impulsive traits, sleep quality, and social support. Genotyping was performed to identify rs6313 polymorphisms in the HTR2A gene of all participants.

Results

The frequencies of the C and T alleles of HTR2A T102C were 28% and 72% in the IAD group and 53% and 47% in the HCs group, respectively, indicating that the differences between these two groups were significant. No significant difference was observed in the distribution of the CC, CT, and TT genotypes of HTR2A gene T102C between the IAD and the HCs groups. Additionally, there was no difference in the distribution of the frequencies of the HTR2A gene T102C CC and CT+TT genotypes between the two groups. However, the distribution between the TT and CC+CT genotypes showed an apparent statistical difference in the HTR2A gene T102C between the two groups. Correlation analysis indicated that the IAT score was positively correlated with the Y-BOCS and BIS scores for the CC+CT genotype in patients with IAD. Moreover, the IAT score was positively correlated with the PSQI score in patients with IAD carrying the TT genotype.

Conclusion

The present study demonstrates that rs6313 in HTR2A is associated with IAD, and that the T allele of rs6313 in HTR2A may be a risk factor for IAD.

The contribution of the 5-hydroxytryptamine receptor 2 A gene polymorphisms rs6311 and rs6313 to Schizophrenia in Iran

OBJECTIVE

Schizophrenia is an acute mental disorder with an undefined etiology. Its high heritability suggests that several genetic variants and polymorphisms may contribute to the severity and emergence of its symptoms. Former molecular evidence has shed some light on the association of serotonergic pathway genetic polymorphisms with schizophrenia. This study aimed to investigate the association between schizophrenia and two SNPs from one haplotype block, which lies in the 5-hydroxytryptamine receptor 2 A (5-HTR2A) gene in the Iranian population.

MATERIAL AND METHODS

Blood samples were collected from one-hundred and fifty-two patients diagnosed with schizophrenia and one-hundred and fifty-eight cases of the healthy control, who were matched in terms of age and gender. The participants were genotyped for rs6311 and rs6313 using PCR-RFLP. R programming language and Haploview software were respectively leveraged for statistical and haplotype inferencing.

RESULTS

The results showed that there was no significant association between rs6313 and schizophrenia. However, the rs6311 T allele was independently associated with schizophrenia, and it was significantly associated with SCZ in an rs6311-rs6313 haplotype. Moreover, the general linear model confirmed the potential predictor role of rs6311 for schizophrenia and the C allele of rs6313 demonstrated a higher frequency among females compared to males.

CONCLUSION

The findings of this study indicated the association of rs6311 and rs6311-rs6313 haplotype with schizophrenia in the Iranian population and also suggested a potential schizophrenia risk predictor role for rs6311.

Chronotype, circadian rhythm, and psychiatric disorders: Recent evidence and potential mechanisms

The circadian rhythm is crucial for physiological and behavioral functions. Chronotype, which represents individual preferences for activity and performance, is associated with human health issues, particularly psychiatric disorders. This narrative review, which focuses on the relationship between chronotype and mental disorders, provides an insight into the potential mechanism. Recent evidence indicates that (1) the evening chronotype is a risk factor for depressive disorders and substance use disorders, whereas the morning chronotype is a protective factor. (2) Evening chronotype individuals with bipolar disorder tend to have more severe symptoms and comorbidities. (3) The evening chronotype is only related to anxiety symptoms. (4) The relationship between chronotype and schizophrenia remains unclear, despite increasing evidence on their link. (5) The evening chronotype is significantly associated with eating disorders, with the majority of studies have focused on binge eating disorders. Furthermore, the underlying mechanisms or influence factors are described in detail, including clock genes, brain characteristics, neuroendocrinology, the light/dark cycle, social factors, psychological factors, and sleep disorders. These findings provide the latest evidence on chronotypes and psychiatric disorders and serve as a valuable reference for researchers.