The CLOCK 3111T/C SNP is associated with morning gastric motility in healthy young women

Circadian locomotor output cycles kaput (CLOCK) molecule plays major roles in circadian rhythmicity and regulates daily physiological processes including digestive activity. Therefore, we hypothesized that the CLOCK 3111T/C single nucleotide polymorphism (SNP) might have adverse effects on the regulation of gastric motility. Based on the hypothesis, we investigated whether this SNP was associated with morning gastric motility. Ninety-five female university students (19.6±0.2 years) completed life-style questionnaires. Gastric motility, evaluated by electrogastrography (EGG), blood pressure (BP), and heart rate variability (HRV) were measured at 8:30 a.m. after an overnight fast. To determine the gastric motility, the spectral powers and dominant frequency (DF, a peak of the spectrum) of the EGG were calculated. No significant differences were found in breakfast frequency, energy intake, or HRV between CLOCK 3111T/C minor C allele (T/C or C/C) and T/T subjects. However, C allele carriers showed significantly lower DF than T/T subjects, suggesting slower gastric motility. Moreover, C allele carriers had a lower heart rate (HR) and tended to have lower diastolic BP compared with T/T subjects. These results support our hypothesis that this SNP is likely correlated with morning gastric motility. Such attenuated gastric and cardiovascular function that characterized CLOCK 3111C allele carriers could be affecting biological behavior in the morning.