Association between apolipoprotein E promoter-219G/T polymorphism and total cholesterol level in patients with Alzheimer disease

BACKGROUND: Many researches have suggested that apolipoprotein E (APOE) and total cholesterol metabolism are closely related with dementia. In the supposed theory, 219 site of APOE promoter region is near gene coding region, so its polymorphism may result in the abnormality of APOE gene and protein expression, and finally lead to dementia. OBJECTIVE: To observe the association between APOE promoter-219G/T polymorphisms with serum total cholesterol in patients with Alzheimer disease, and compare it with non-dementia people. DESIGN: Case-control, comparative observation. SETTING: Department of Neurology, Fengtian Hospital of Shenyang Medical College. PARTICIPANTS: Fifty-five dementia patients including 27 males and 28 females aged (66±3) years and treated in the Department of Neurology, Fengtian Hospital were selected from January 2002 to December 2005 as the Alzheimer disease group. They all diagnosed according to the DSM-Ⅳdiagnostic criteria of Alzheimer disease instituted by American Psychiatry Association in 1994. Meanwhile, 44 none-dementia patients including 21 males and 23 females aged (66±3) years were selected from other clinical departments of Fengtian Hospital as control group. All the participants were informed the detection and agreed. METHODS: Genomic DNA was extracted from the peripheral blood of all subjects, then "NEST"PCR, DNA sequence and enzyme digestion were adopted to detect the expression of APOE promoter-219 polymorphism, following by biomedical statistics analysis based on the clinical total cholesterol level. MAIN OUTCOME MEASURES: Polymorphism of APOE promoter-219 G/T and total cholesterol level. RESULTS: All 55 dementia patients and 44 non-dementia ones were involved in the result analysis. ①Allele and genotype frequency: The T allele frequency of the Alzheimer disease group was significantly higher than that in the control group [88.2% (97/110), 54.5% (48/88)], while G allele frequency was remarkably lower than that in the control group [11.8%(13/110), 45.5%(40/88), χ2=8.2, P < 0.01]. The TT allele frequency of the Alzheimer disease group was significantly higher than that in the control group [76% (42/55), 48% (21/44)], while GT+GG allele frequency was remarkably lower than that in the control group [24%(13/55), 52%(23/44), χ2=8.7, P < 0.01]. ②Total cholesterol level: The level of the TT genotype patients in the Alzheimer group was obviously higher than that in GT+GG genotype patients (t =2.46, P < 0.05); the cholesterol level in the two genotypes of the control group was similar (P > 0.05). CONCLUSION: TT genotype and allele T in the APOE promoter-219 polymorphisms are the sensitive gene, and genotype TT has a relationship with the increase of total cholesterol level.