Apolipoprotein E - e4
e4/e4 AD patients show markedly more APP
deposition in plaques relative to non-e4 AD
patients
ApoE e4 binds BA4 peptide with greater avidity
than e3 isoform.
ApoE e4 shows significant allelic association in
familial and sporadic late onset AD, and in familial
early onset AD.
e4 heterozygote is 3X more likely to be affected than e2/e3
or e3/e3
e4 homozygote is 8X more likely to be affected
Conclusion: ApoE e4 gene dose is a major risk factor
for late (and possibly early) onset AD.  Inheritance
of two e4 alleles is not necessary and probably not
sufficient to cause AD.