Objectives: In the present study, it was examined whether polymorphism of circadian locomotor output cycle kaput (CLOCK) gene 3111T/C was associated with susceptibility of Alzheimer disease (AD).
Methods: This study was conducted using a case-control method. Genotypes of apolipoprotein E (APOE e4) and CLOCK gene 3111T/C were determined by restriction fragment length polymorphism method and TaqMan assay method, respectively.
Results: In this study, we gathered 296 unrelated AD patients and 423 control subjects. Both in the whole sample and APOE e4 noncarriers, prevalence of C carriers in CLOCK gene 3111T/C in AD patients was significantly higher than that in control subjects (in the whole sample: χ2 = 37.615, P < 0.0001; in APOE e4 noncarriers: χ2 = 46.809, P < 0.0001). However, among APOE e4 carriers, prevalence of C carriers in CLOCK gene 3111T/C between patients and control subjects presents nonsignificant difference (χ2 = 0.812, P = 0.451).
Conclusions: Among APOE e4 noncarriers, C carriers in CLOCK gene 3111T/C were associated with a high susceptibility of AD, but among APOE e4 carriers, the functional polymorphism of CLOCK gene 3111T/C was not associated with the susceptibility of AD.