title: Circadian rhythm genes CLOCK and PER3 polymorphisms and morning gastric motility in humans.
abstract: BACKGROUND
  Clock genes regulate circadian rhythm and are involved in various physiological processes, including digestion. We therefore investigated the association between the CLOCK 3111T/C single nucleotide polymorphism and the Period3 (PER3) variable-number tandem-repeat polymorphism (either 4 or 5 repeats 54 nt in length) with morning gastric motility.
  
  
  METHODS
  Lifestyle questionnaires and anthropometric measurements were performed with 173 female volunteers (mean age, 19.4 years). Gastric motility, evaluated by electrogastrography (EGG), blood pressure, and heart rate levels were measured at 8:30 a.m. after an overnight fast. For gastric motility, the spectral powers (% normal power) and dominant frequency (DF, peak of the power spectrum) of the EGG were evaluated. The CLOCK and PER3 polymorphisms were determined by polymerase chain reaction (PCR) restriction fragment length polymorphism analysis.
  
  
  RESULTS
  Subjects with the CLOCK C allele (T/C or C/C genotypes: n = 59) showed a significantly lower DF (mean, 2.56 cpm) than those with the T/T genotype (n = 114, 2.81 cpm, P < 0.05). Subjects with the longer PER3 allele (PER34/5 or PER35/5 genotypes: n = 65) also showed a significantly lower DF (2.55 cpm) than those with the shorter PER34/4 genotype (n = 108, 2.83 cpm, P < 0.05). Furthermore, subjects with both the T/C or C/C and PER34/5 or PER35/5 genotypes showed a significantly lower DF (2.43 cpm, P < 0.05) than subjects with other combinations of the alleles (T/T and PER34/4 genotype, T/C or C/C and PER34/4 genotypes, and T/T and PER34/5 or PER35/5 genotypes).
  
  
  CONCLUSIONS
  These results suggest that minor polymorphisms of the circadian rhythm genes CLOCK and PER3 may be associated with poor morning gastric motility, and may have a combinatorial effect. The present findings may offer a new viewpoint on the role of circadian rhythm genes on the peripheral circadian systems, including the time-keeping function of the gut.
authors.affiliation: Graduate School of Human Science and Environment, University of Hyogo, Hyogo, Japan.
authors.forename: Mitsue
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: Department of Clinical Laboratory Medicine, Jichi Medical University, Shimotsuke-Tochigi, Japan; Division of Preventive Medicine, Clinical Research Institute for Endocrine and Metabolic Disease, National Hospital Organization, Kyoto Medical Center, Kyoto, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kotani
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute for Endocrine and Metabolic Disease, National Hospital Organization, Kyoto Medical Center, Kyoto, Japan.
authors.forename: Kokoro
authors.initials: K
authors.lastname: Tsuzaki
authors.affiliation: Graduate School of Human Science and Environment, University of Hyogo, Hyogo, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Takagi
authors.affiliation: Graduate School of Human Science and Environment, University of Hyogo, Hyogo, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Motokubota
authors.affiliation: Graduate School of Human Science and Environment, University of Hyogo, Hyogo, Japan.
authors.forename: Naho
authors.initials: N
authors.lastname: Komai
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute for Endocrine and Metabolic Disease, National Hospital Organization, Kyoto Medical Center, Kyoto, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Sakane
authors.affiliation: Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Moritani
authors.affiliation: Graduate School of Human Science and Environment, University of Hyogo, Hyogo, Japan.
authors.forename: Narumi
authors.initials: N
authors.lastname: Nagai
mesh_terms: D000204:Activity Cycles; D056926:CLOCK Proteins / Q000235:genetics*; D005260:Female; D005769:Gastrointestinal Motility / Q000235:genetics*; D006801:Humans; D056950:Period Circadian Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D055815:Young Adult
chemical_list: C512644:PER3 protein, human; D056950:Period Circadian Proteins; D056926:CLOCK Proteins; C538943:CLOCK protein, human