Alzheimer’s Disease AD of Jon SDSUGrad Sandbox TEST11 Apolipoprotein E
Thursday, December 11th, 2008APOE-?4 has been shown to cause an increased susceptibility to Alzheimer’s disease.[3] The pivotal role of ApoE in AD was first identified through linkage analysis by Margaret Pericak-Vance while working in the Roses lab at Duke University. Linkage studies were followed by association analysis confirming the role of the APOE-?4 allele.
Although 40-65% of AD patients have at least one copy of the 4 allele ApoE4 is not a determinant of the disease - at least a third of patients with AD are ApoE4 negative and some ApoE4 homozygotes never develop the disease.
Among ApoE4 carriers, another gene, GAB2, is thought to further influence the risk of getting AD.[4]
There is also evidence that the 2 allele may serve a protective role in AD.[5]
Thus, the genotype most at risk for Alzheimer’s disease and at earlier age is ApoE 4,4. The ApoE 3,4 genotype is at increased risk, though not to the degree that those homozygous for ApoE 4 are. The genotype ApoE 3,3 is considered at normal risk for Alzheimer’s disease. The genotype ApoE 2,3 is considered at less risk for Alzheimer’s disease. Interestingly, people with both a copy of the 2 allele and the 4 allele, ApoE 2,4, are at normal risk similar to the ApoE 3,3 genotype.