Study of a Functional Polymorphism in the PER3 Gene and Diurnal Preference in a Colombian Sample

Abstract

Polymorphisms in human clock genes have been evaluated as potential factors influencing circadian phenotypes in several populations. There are conflicting results for the association of a VNTR in the PER3 gene and diurnal preference in different studies. The objective of this study was to investigate the association between diurnal preference and daytime somnolence with the PER3 VNTR polymorphism (rs57875989) in healthy subjects from Colombia, a Latin American population.A total of 294 undergraduate university students from Bogotá, Colombia participated in this study. Two validated self-report questionnaires, the Composite Scale of Morningness (CSM) and the Epworth Sleep Scale (ESS) were used to assess diurnal preference and daytime somnolence, respectively. Individuals were genotyped for the PER3 VNTR using conventional PCR. Statistical comparisons were carried out with PLINK and SNPStats programs.The PER3 VNTR polymorphism was not associated with either diurnal preference or daytime somnolence in this population. No significant differences in mean scores for those scales were found between PER3 VNTR genotypes. In addition, there were no differences in allelic or genotypic frequencies between chronotype categories. This is consistent with several negative findings in other populations, indicating that the proposed influence of this polymorphism in diurnal preference, and related endophenotypes of neuropsychiatric importance, needs further clarification. This is the first report of molecular genetics of human circadian phenotypes in a Spanish-speaking population.

PER Gene Family Polymorphisms in Relation to Cluster Headache and Circadian Rhythm in Sweden

“…There have been conflicting results regarding the long tandem repeat rs57875989 and its association with diurnal preference [22,[34][35][36]. There are multiple studies which, in agreement with our results, did not find a correlation between chronotype and rs57875989 [34][35][36].…”

“…Hida et al found the G allele of rs228697 to be linked with eveningness, while the C allele was connected to morningness, in a large material consisting of 925 controls [21]. There have been conflicting results regarding the long tandem repeat rs57875989 and its association with diurnal preference [22,[34][35][36]. There are multiple studies which, in agreement with our results, did not find a correlation between chronotype and rs57875989 [34][35][36].…”

“…Genotype based on diurnal preference was also investigated to see if our results could back-up previous findings by other research groups [12,14,17,21,22,[34][35][36]. No significant association was found between any of the genetic variants and diurnal preference.…”

Diurnal preference, mood and the response to morning light in relation to polymorphisms in the human clock gene PER3

“…In the present study, no relationship was observed between the PER3 4 – PER3 5 VNTR polymorphism and diurnal preference. The available literature is conflicting in this respect, with at least three studies documenting this association 7 , 16 , 17 and others failing to replicate it 18 – 20 . Several factors could explain these discrepancies.…”

Investigation of gene-gene interactions of clock genes for chronotype in a healthy Korean population

“…Several positive associations for chronotype in European populations have been reported. In addition, negative findings were also reported for European populations [39][40][41] and Asian populations [42,43]. The circadian clock system consists mainly of transcription-translation feedback loops in the internal timekeeping clock.…”