A silent polymorphism in the PER1 gene associates with extreme diurnal preference in humans

J Hum Genet. 2006;51(12):1122-1125. doi: 10.1007/s10038-006-0060-y. Epub 2006 Oct 19.


The three PERIOD proteins form a major negative feedback component of the molecular mechanism governing the periodicity of the vertebrate circadian clock. Genetic variations within the human PER2 and PER3 genes have been linked with diurnal preference and disorders of sleep timing. We screened the coding region of PER1, as well as the 5'- and 3'-untranslated regions and the promoter region, for polymorphisms. The T2434C polymorphism in exon 18, a synonymous substitution, associated with extreme diurnal preference. The C allele was more frequent in subjects with extreme morning preference (frequency=0.24) than in subjects with extreme evening preference (frequency=0.12). No significant association was observed between either allele and delayed sleep phase syndrome. This polymorphism may have a direct effect on RNA translatability, or be in linkage disequilibrium with another polymorphism which affects PER1 expression at the DNA, RNA, or protein level. This is the first reported association between a PER1 polymorphism and extreme diurnal preference. Functionally important polymorphisms in PER1 are rare, which may indicate that it is subject to more stringent selection pressure than the other PER genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions
  • 5' Untranslated Regions
  • Cell Cycle Proteins / genetics*
  • Circadian Rhythm / genetics*
  • Gene Frequency
  • Humans
  • Period Circadian Proteins
  • Polymorphism, Genetic*
  • Promoter Regions, Genetic
  • Sleep / genetics
  • Sleep Disorders, Circadian Rhythm / genetics


  • 3' Untranslated Regions
  • 5' Untranslated Regions
  • Cell Cycle Proteins
  • PER1 protein, human
  • Period Circadian Proteins