title: Genetic differences in human circadian clock genes among worldwide populations.
abstract: The daily biological clock regulates the timing of sleep and physiological processes that are of fundamental importance to human health, performance, and well-being. Environmental parameters of relevance to biological clocks include (1) daily fluctuations in light intensity and temperature, and (2) seasonal changes in photoperiod (day length) and temperature; these parameters vary dramatically as a function of latitude and locale. In wide-ranging species other than humans, natural selection has genetically optimized adaptiveness along latitudinal clines. Is there evidence for selection of clock gene alleles along latitudinal/photoperiod clines in humans? A number of polymorphisms in the human clock genes Per2, Per3, Clock, and AANAT have been reported as alleles that could be subject to selection. In addition, this investigation discovered several novel polymorphisms in the human Arntl and Arntl2 genes that may have functional impact upon the expression of these clock transcriptional factors. The frequency distribution of these clock gene polymorphisms is reported for diverse populations of African Americans, European Americans, Ghanaians, Han Chinese, and Papua New Guineans (including 5 subpopulations within Papua New Guinea). There are significant differences in the frequency distribution of clock gene alleles among these populations. Population genetic analyses indicate that these differences are likely to arise from genetic drift rather than from natural selection.
authors.affiliation: Department of Biological Sciences, Neuroscience Graduate Program, Vanderbilt University, Nashville, TN, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Ciarleglio
authors.forename: Kelli K
authors.initials: KK
authors.lastname: Ryckman
authors.forename: Stein V
authors.initials: SV
authors.lastname: Servick
authors.forename: Akiko
authors.initials: A
authors.lastname: Hida
authors.forename: Sam
authors.initials: S
authors.lastname: Robbins
authors.forename: Nancy
authors.initials: N
authors.lastname: Wells
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hicks
authors.forename: Sydney A
authors.initials: SA
authors.lastname: Larson
authors.forename: Joshua P
authors.initials: JP
authors.lastname: Wiedermann
authors.forename: Krista
authors.initials: K
authors.lastname: Carver
authors.forename: Nalo
authors.initials: N
authors.lastname: Hamilton
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Kidd
authors.forename: Judith R
authors.initials: JR
authors.lastname: Kidd
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Smith
authors.forename: Jonathan
authors.initials: J
authors.lastname: Friedlaender
authors.forename: Douglas G
authors.initials: DG
authors.lastname: McMahon
authors.forename: Scott M
authors.initials: SM
authors.lastname: Williams
authors.forename: Marshall L
authors.initials: ML
authors.lastname: Summar
authors.forename: Carl Hirschie
authors.initials: CH
authors.lastname: Johnson
mesh_terms: D056930:ARNTL Transcription Factors; D001741:Black or African American; D000483:Alleles; D044466:Asian People; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D001683:Biological Clocks / Q000235:genetics* / Q000502:physiology; D056926:CLOCK Proteins; D002940:Circadian Rhythm / Q000235:genetics* / Q000502:physiology; D004247:DNA / Q000235:genetics; D005787:Gene Frequency; D005796:Genes; D005869:Ghana; D006801:Humans; D008027:Light; D009512:New Guinea; D017440:Photoperiod; D011110:Polymorphism, Genetic; D011153:Population / Q000235:genetics*; D012621:Seasons; D013696:Temperature; D015534:Trans-Activators / Q000235:genetics*; D014481:United States; D044465:White People
chemical_list: D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D004247:DNA; D015534:Trans-Activators; C538960:BMAL1 protein, human; C486615:BMAL2 protein, human; C538943:CLOCK protein, human