ARNTL, CLOCK and PER3 polymorphisms - links with chronotype and affective dimensions

Area of Science:

• Genetics
• Psychiatry
• Chronobiology

Background:

• Previous research linked specific gene single nucleotide polymorphisms (SNPs) in ARNTL, TIM, and PER3 to affective temperaments in bipolar disorder patients.
• The relationship between chronotype, affective temperaments, and genetic predispositions requires further investigation in non-clinical populations.

Purpose of the Study:

• To investigate if ARNTL, TIM, and PER3 gene SNPs associated with affective temperaments in bipolar patients are also present in a non-clinical student sample.
• To explore the relationship between these SNPs and other affective dimensions, as well as their role in mediating the connection between chronotype and affective traits.

Main Methods:

• Genotyping of seven single nucleotide polymorphisms (SNPs) in the ARNTL, TIM, and PER3 genes.
• Administration of multiple questionnaires assessing temperament, depression, stress, general health, seasonality, and chronotype to 338 university students.
• Statistical analysis to examine associations between SNPs, affective temperaments, dimensions, and chronotype.

Main Results:

• ARNTL rs7107287 showed nominal association with cyclothymic temperament, depressive symptoms, stress, mental health, and seasonality impact.
• TIM rs10876890 was nominally associated with hyperthymic temperament, and TIM rs2291738 with chronotype.
• The study found that different SNPs related to chronotype and affective temperaments, suggesting they do not underpin the observed relationships between eveningness/morningness and affective dysfunction.

Conclusions:

• The study suggests distinct genetic underpinnings for chronotype and affective temperaments/dimensions in a non-clinical sample.
• Observed associations between chronotype (eveningness/morningness) and affective traits (e.g., dysthymic, hyperthymic temperaments, depressive symptoms) were not explained by the investigated SNPs.
• The identified SNP associations require further replication as they did not meet stringent statistical significance criteria (Bonferroni correction).