Question: Which ApoE isoform is associated with atherosclerosis and Alzheimer's disease?

Context:
Among three isoforms, the apoE4 isoform is associated with increased frequency of atherosclerosis and Alzheimer's disease (AD). 
Homozygosity for ApoE epsilon4 is associated with atherosclerosis and Alzheimer's disease whereas ApoE epsilon2 and epsilon3 tend to be protective.
Importantly, lipoproteins containing the apoE3 isoform had higher TGF-beta levels and bioactivity than those containing apoE4, a major genetic risk factor for atherosclerosis and Alzheimer's disease. 
ApoE4 is positively associated with atherosclerosis and late-onset and sporadic Alzheimer's disease (AD). 
Isoform (allele)-specific effects include the association of apoE2 with the genetic disorder type III hyperlipoproteinemia and with both increased and decreased risk for atherosclerosis and the association of apoE4 with increased risk for both atherosclerosis and Alzheimer's disease, impaired cognitive function, and reduced neurite outgrowth; isoform-specific differences in cellular signaling events may also exist. 
Although APOE-epsilon3 is considered a longevity gene, APOE-epsilon4 is a dual risk factor to atherosclerosis and Alzheimer disease.
The apolipoprotein E (apoE) type epsilon 4 isoform specifies increased cerebral and cerebrovascular accumulation of amyloid-beta protein (A beta) and contributes to the genetic susceptibility underlying a large proportion (approximately 60%) of typical, sporadic Alzheimer disease.
The structural preference of apoE4 to remain functional in solution may explain the enhanced opportunity of apoE4 isoform to display its pathophysiologic functions in atherosclerosis and Alzheimer disease.
The apolipoprotein E (APOE) E4 allele is associated with Alzheimer's disease, cardiovascular disease, and decreased longevity.
The apolipoprotein E type 4 allele is a susceptibility gene for late-onset Alzheimer's disease.
The apolipoprotein E (ApoE) ε4 allele is the strongest risk factor of sporadic Alzheimers disease (AD), however, the fluid concentrations of ApoE and its different isoforms (ApoE2, ApoE3 and ApoE4) in AD patients and among APOE genotypes (APOE ε2, ε3, ε4) remain controversial
Among three isoforms, the apoE4 isoform is associated with increased frequency of atherosclerosis and Alzheimers disease (AD)
Homozygosity for ApoE epsilon4 is associated with atherosclerosis and Alzheimers disease whereas ApoE epsilon2 and epsilon3 tend to be protective
Homozygosity for ApoE epsilon4 is associated with atherosclerosis and Alzheimer's disease whereas ApoE epsilon2 and epsilon3 tend to be protective. 
Although APOE-epsilon3 is considered a longevity gene, APOE-epsilon4 is a dual risk factor to atherosclerosis and Alzheimer disease. 
The apoE4 allele is a major risk factor for late-onset familial and sporadic Alzheimer's disease (AD) and is associated with a poor outcome after brain injury. 
Among three isoforms, the apoE4 isoform is associated with increased frequency of atherosclerosis and Alzheimer's disease (AD).
Homozygosity for ApoE epsilon4 is associated with atherosclerosis and Alzheimer's disease whereas ApoE epsilon2 and epsilon3 tend to be protective.
Importantly, lipoproteins containing the apoE3 isoform had higher TGF-beta levels and bioactivity than those containing apoE4, a major genetic risk factor for atherosclerosis and Alzheimer's disease.
Isoform (allele)-specific effects include the association of apoE2 with the genetic disorder type III hyperlipoproteinemia and with both increased and decreased risk for atherosclerosis and the association of apoE4 with increased risk for both atherosclerosis and Alzheimer's disease, impaired cognitive function, and reduced neurite outgrowth; isoform-specific differences in cellular signaling events may also exist.
The decreased antioxidant activity of E4 could contribute to its association with Alzheimer's disease, cardiovascular disease and decreased longevity.
The isoform apoE4 is associated with an increased risk of Alzheimer's disease and it has been postulated that high intracellular cholesterol levels promote the amyloidogenic processing of amyloid precursor protein.
Among three ɛ2, ɛ3, ɛ4 alleles, ɛ4 allele is associated with the increase in cholesterol level, risk of atherosclerosis and Alzheimer disease, while ɛ2 allele is associated with the decrease in cholesterol level and risk of atherosclerosis.
Although APOE-epsilon3 is considered a longevity gene, APOE-epsilon4 is a dual risk factor to atherosclerosis and Alzheimer disease.
The structural preference of apoE4 to remain functional in solution may explain the enhanced opportunity of apoE4 isoform to display its pathophysiologic functions in atherosclerosis and Alzheimer disease..

Answer: The ApoE4 isoform is associated with increased frequency of atherosclerosis and Alzheimer's disease (AD).
Exact answer: ApoE4 isoform, Apolipoprotein E4 isoform