Frequency of the Apolipoprotein E ε4 Allele in a Memory Clinic Cohort in Beijing: A Naturalistic Descriptive Study

OBJECTIVES To describe the distribution of apolipoprotein E (APOE) genotypes among an elderly Chinese patient population with memory complaints treated in a memory clinic in Beijing and to compare the ε4 allele frequency among individuals with subjective cognitive impairment (SCI), mild cognitive impairment (MCI) and Alzheimer's disease (AD). METHODS A total of 385 subjects with memory complaints participated in the study, including 216 patients with AD, 56 with MCI, 17 with SCI, and 96 with other types of cognitive impairment. A total of 75 healthy elderly control subjects were also recruited. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to investigate the APOE genotypes. RESULTS The frequency of the ε4 allele was 19.6 percent for the entire sample of patients who had memory complaints. The APOE allele distribution differed between women and men (22.6% and 14.9%, respectively; p<0.05) in the individuals with memory complaints. Compared with the control group (7.3%), the prevalence of the APOE ε4 allele was significantly higher in the AD (23.6%) and MCI (21.4%) groups and was slightly increased in the SCI (14.7%) group. CONCLUSIONS In the memory clinic, we observed a higher prevalence of the APOE ε4 allele among Chinese AD and MCI patients. A similar trend was observed in patients with SCI. These findings suggest that nondemented APOE ε4 allele carriers with memory complaints may have a greater genetic risk for AD and should be monitored more closely.