Apolipoprotein E: high-avidity binding to beta-amyloid and increased frequency of type 4 allele in late-onset familial Alzheimer disease.

TLDR

Apolipoprotein E localizes to senile plaques, vascular amyloid, and neurofibrillary tangles, binds the beta‑amyloid A4 peptide with high avidity via residues 12‑28, and its gene on chromosome 19q13.2 lies within a region linked to late‑onset familial Alzheimer disease. The study proposes a functional role for the APOE‑E4 isoform in the pathogenesis of late‑onset familial Alzheimer disease. Analysis showed a highly significant association between the APOE‑E4 allele and late‑onset familial Alzheimer disease, with an allele frequency of 0.50 in affected patients versus 0.16 in controls (Z = 2.44, P = 0.014).

Abstract

Apolipoprotein E is immunochemically localized to the senile plaques, vascular amyloid, and neurofibrillary tangles of Alzheimer disease. In vitro, apolipoprotein E in cerebrospinal fluid binds to synthetic beta A4 peptide (the primary constituent of the senile plaque) with high avidity. Amino acids 12-28 of the beta A4 peptide are required. The gene for apolipoprotein E is located on chromosome 19q13.2, within the region previously associated with linkage of late-onset familial Alzheimer disease. Analysis of apolipoprotein E alleles in Alzheimer disease and controls demonstrated that there was a highly significant association of apolipoprotein E type 4 allele (APOE-epsilon 4) and late-onset familial Alzheimer disease. The allele frequency of the APOE-epsilon 4 in 30 random affected patients, each from a different Alzheimer disease family, was 0.50 +/- 0.06; the allele frequency of APOE-epsilon 4 in 91 age-matched unrelated controls was 0.16 +/- 0.03 (Z = 2.44, P = 0.014). A functional role of the apolipoprotein E-E4 isoform in the pathogenesis of late-onset familial Alzheimer disease is suggested.