BACKGROUND: Apolipoprotein E (ApoE) gene polymorphism is associated with the onset of Alzheimer disease (AD), most of the researchers reported that ApoE ε4 allele accounts for familial AD as well as for sporadic AD.OBJECTIVE: This study was designed to validate the relationship between ApoE gene polymorphism and the sporadic AD in Aged Adults in Urumqi, and to evaluate the value of ApoE gene for prediction the risk of sporadic AD.DESIGN: Controlled comparative study based on patients.SETTING: It was conducted at the Institute of Clinical Medicine and the Neurological Department of Urumqi General Hospital of Lanzhou Military Area Command of Chinese PLA.PARTICIPANTS: From January 2001 to January 2003, 60 aged inpatients and outpatients at the Neurological Department of Urumqi General Hospital of Lanzhou Military Area Command of Chinese PLA and elderly in the Old People's Home were screened for AD. Of all these participants,28 were males and 32 were females, with an age from 52 to 91, in average of (74.2±19.5) years old, They had 0-16 years education, in average of 4.43 years, 28 were illiterate, 13 were at primary school educational level,12 were at junior middle school educational level, 4 were at high school educational level and 3 were at college educational level. From February to December 2002, 90 genetically unrelated individuals with healthy physical examination findings in Xinjiang area were selected into control group, 59males and 31 females, with an age from 50 to 101 years old, in average of (69.9±25.5) years old, have 0-16 year's education, in average of 7.96years. Of all the controls, 14 were illiterate, 23 were at primary educational level, 25 were at junior middle school educational level, 21 were at high school educational level and 7 were at college educational level. Informed consents were obtained from all the participants.METHODS: 5 Ml blood samples, anticoagulated with ethylene diamine tetraacetic acid (EDTA), were drawn from each participant. Then genome DNA was extracted from peripheral white blood cells using the phenolchloroform method. A fragment containing polymorphism site in exon 4 of ApoE were amplified using the polymerase chain reaction (PCR), were digested with Hha I and were identified using electrophoresis and silver staining. Then, ApoE genotypes and the frequency of ApoE alleles were compared between AD group and control group.MAIN OUTCOME MEASURES: ① ApoE genotypes and the frequency of ApoE alleles were measured in AD group and control group. ② The frequency of ApoE alleles were calculated in participants with different sex,age and educational level in AD group and control group.RESULTS: Sixty patients with AD and 90 healthy individuals participated this investigation. All of them entered the statistical analysis procedure.① The frequency of ε3/ε4 and ε4/ε4 alleles was higher in AD group than in control group (26.67%,11.11%; 3.33%, 1.11%; P ＜ 0.05). The frequency of e2/ε3 in AD group were lower than control group (5.00%,14.00%, P ＜0.05). ② The frequency of ApoE ε4 allele were higher in AD group as compared with control group (17.50%, 7.22%, P ＜ 0.05). The frequency of ApoE ε2 allele were lower in AD group (6.67%, 13.33%, P ＜ 0.05). ③ The frequency of ApoE ε4 allele in females were higher in AD group than in control group (20.97%, 5.00%, P ＜ 0.01). ④ In AD group, patients ≥ 75 years old have a lower frequency of ApoE ε4 allele compared to those less than 75 years (8.57%, 30.00%, P ＜ 0.01). And in individuals less than 75 years old, the frequency of ApoE ε4 allele were higher in AD group than that in control group (30.00%, 7.02%, P ＜ 0.01). ⑤ In illiterate persons and the individuals with only primary school educational level, the frequency of ApoE ε4 allele were higher in AD group than that in control group (10.00%, 0.56%, P ＜ 0.001; 5.00%,1.12%, P ＜ 0.01).CONCLUSION: ① It is proved that ApoE ε4 allele is significantly associated with sporadicAD in Urumqi and ε3/ε4 is the major genotype. ② ApoE ε2 allele has a protective effect on onset of AD. ③ Those individuals，female,less than 75,lower educational level or carrying ApoE ε4 allele take a higher risk of AD.