Journal
BRAZILIAN JOURNAL OF MEDICAL AND BIOLOGICAL RESEARCH
Volume 41, Issue 8, Pages 716-721Publisher
ASSOC BRAS DIVULG CIENTIFICA
DOI: 10.1590/S0100-879X2008000800013
Keywords
human clock genes; chronotype; morningness/eveningness; association studies; latitudinal hypothesis
Categories
Ask authors/readers for more resources
Individual circadian clocks entrain differently to environmental cycles (zeitgebers, e. g., light and darkness), earlier or later within the day, leading to different chronotypes. In human populations, the distribution of chronotypes forms a bell-shaped curve, with the extreme early and late types - larks and owls, respectively - at its ends. Human chronotype, which can be assessed by the timing of an individual's sleep-wake cycle, is partly influenced by genetic factors - known from animal experimentation. Here, we review population genetic studies which have used a questionnaire probing individual daily timing preference for associations with polymorphisms in clock genes. We discuss their inherent limitations and suggest an alternative approach combining a short questionnaire (Munich ChronoType Questionnaire, MCTQ), which assesses chronotype in a quantitative manner, with a genome-wide analysis (GWA). The advantages of these methods in comparison to assessing time-of-day preferences and single nucleotide polymorphism genotyping are discussed. In the future, global studies of chronotype using the MCTQ and GWA may also contribute to understanding the influence of seasons, latitude ( e. g., different photoperiods), and climate on allele frequencies and chronotype distribution in different populations.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available