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Do Caucasian and Asian clocks tick differently?

A A Barbosa1, M Pedrazzoli, B D V Koike

  • 1Departamento de Psicobiologia, Instituto do Sono, Universidade Federal de São Paulo, São Paulo, Brasil.

Brazilian Journal of Medical and Biological Research = Revista Brasileira De Pesquisas Medicas E Biologicas
|December 8, 2009
PubMed
Summary
This summary is machine-generated.

Genetic variations in Period 3 (PER3) and Clock (CLOCK) genes show distinct allele frequencies between Asian and Caucasian populations in Brazil. These findings highlight ethnic differences in circadian rhythm genetics and their evolutionary implications.

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Area of Science:

  • Genetics
  • Chronobiology
  • Human Evolution

Background:

  • The Period 3 (PER3) and Clock (CLOCK) genes are crucial for the mammalian molecular circadian system.
  • Previous studies indicate associations between clock gene polymorphisms and circadian phenotypes across diverse populations.
  • Ethnic variations in allele frequency and genotyping distribution for clock genes are consistently reported.

Purpose of the Study:

  • To investigate and compare the distribution patterns of PER3 and CLOCK gene polymorphisms in Asian and Caucasian populations residing in Brazil.
  • To explore potential clues regarding human evolutionary processes influencing circadian rhythms.
  • To assess the impact of ethnic variations on the interpretation of circadian rhythm association studies.

Main Methods:

  • Evaluation of two well-studied polymorphisms: a variable number of tandem repeats (VNTR) in the PER3 gene and a single nucleotide polymorphism (SNP) in the CLOCK gene.
  • Analysis of genetic data from 109 individuals of Asian descent and 135 individuals of Caucasian descent living in Brazil.
  • Statistical comparison of allele frequencies between the two ethnic groups.

Main Results:

  • Significantly higher frequencies of the shorter allele (4 repeats) in PER3 and the T allele in CLOCK were observed in the Asian population (0.86 and 0.84, respectively) compared to the Caucasian population (0.69 and 0.71, respectively).
  • The study confirmed distinct distribution patterns of these specific PER3 and CLOCK gene polymorphisms between the Asian and Caucasian ethnic groups.
  • The observed genetic differences underscore ethnic variations in circadian clock gene polymorphisms.

Conclusions:

  • Ethnic variations in PER3 and CLOCK gene polymorphisms are evident between Asian and Caucasian populations in Brazil.
  • These genetic differences have implications for interpreting results from circadian rhythm association studies.
  • The findings raise questions about the evolutionary pressures that have shaped these variations in human circadian clock genes.