The Relationship Of Apolipoprotein E Polymorphism And Age At Onset Of Alzheimer's Disease

Background and PurposeThe ApoE?4 allele have been considered risk factors both late-onset familial alzheimer's disease(FAD)and the late-onset sporadic alzheimer's disease(SAD). ApoE?4 allele and the age of onset(AAO) of AD may be relevant. But this effect was great differences among different ethnic and ApoE genotype of AD patients. since ApoE allele and genotype distribution were different among different types of AD. Few studies on this aspect of domestic, the main focus on the relationship between APOE gene and AAO of SAD. To expore the correlation between the ApoE Polymorphism and AAO of SAD and FAD patients of Han population in China. MethodsThere were 238 Probable AD patients:40 patients with FAD, with at least 1 family member with dementia; 198 patients with SAD; We used polymerasechain reaction-restriction fragment lengthpolymorphism(PCR-RLFP) to test ApoE genotype. We used ?2 tests for categorical variables and analysis of variance in ApoE allele and genotype distribution among different types of AD. The linkage between ApoE polymorphism and AAO of SAD and FAD were analyzed by one-way ANOVA.General Linear Model(GLM) is used to analyze the influence factors of AAO of SAD. ResultsThe mean age of the total AD patients was(73.8±6.1) years. The mean AAO of AD was significantly lower in FAD than in SAD:(71.7±5.2)years vs(74.3±6.2) years(P<0.05). There was no significant difference in ApoE allele and genotype distribution between SAD and FAD. A statistically significant dose effect of the ApoE genetype was present for AAO in SAD(F=2.525,P=0.042), the order of age were?2/3>?3/3>?3/4>?2/4>?4/4, but not in FAD(F=1.124,P=0.352). There was no significant difference on AAO of AD with SAD and FAD Whether they carry ?2 gene.The decrease in AAO of AD with increasing number of APOE ?4 alleles was significant among patients with SAD(AD: F=6.223, P=0.002; SAD: F=4.316, P=0.0015), but not those with FAD(F=1.728, P=0.192). We used GLM that adjusted Other factors with AAO of SAD yielded the following result: there was no significant difference on AAO of SAD when hypertension, hypercholesterolaemia and stroke were present, The decrease in AAO of AD with increasing number of APOE ?4 alleles was significant among patients with SAD, diabetes mellitus has marginal statistically significant differences for its onset age(P=0.058). ConclusionsThe mean AAO of AD was significantly lower in FAD than in SAD; There was no significant difference in ApoE allele and genotype distribution between SAD and FAD;Apolipoprotein E ?4 had a consistent lowering effect on AAO of SAD in a dose-dependent manner. but this was no significant difference in SAD.