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.