OBJECTIVE: To examine the association between the circadian locomotor output 
cycles kaput (CLOCK) gene rs1554483 G/C polymorphism and susceptibility to 
Alzheimer's disease in Chinese people.
METHODS: This case-control study determined apolipoprotein E (APOE) and CLOCK 
rs1554483 G/C genotypes using polymerase chain reaction restriction fragment 
length polymorphism.
RESULTS: Unrelated patients with Alzheimer's disease (n = 130) and healthy 
controls (n = 188) were analysed for an association between the CLOCK gene 
rs1554483 G/C polymorphism and susceptibility to Alzheimer's disease. In the 
whole sample and in APOE ε4 isoform noncarriers, the prevalence of CLOCK gene 
rs1554483 G allele carriers was significantly higher in patients with 
Alzheimer's disease than in controls. Among APOE ε4 carriers, the prevalence of 
CLOCK rs1554483 G allele carriers was not significantly different between 
patients with Alzheimer's disease and controls.
CONCLUSION: Among APOE ε4 noncarriers, but not APOE ε4 carriers, the CLOCK 
rs1554483 G allele was associated with increased susceptibility to Alzheimer's 
disease.