P3-173: Apolipoprotein E frequency in posterior cortical atrophy and typical Alzheimer’s disease

Abstract

Typical Alzheimer's disease (AD) is characterized by early episodic memory loss, whereas Posterior Cortical Atrophy (PCA) is characterized by visual agnosias, with a relative sparing of episodic memory early in the disease course. The majority of cases of PCA share pathological features with those of typical AD. A well defined risk factor of typical AD is the presence of the apolipoprotein E (APOE) 4 allele. To compare the APOE 4 allele frequency in typical AD and PCA. We conducted a case control study in which the APOE status was determined on 22 patients who fulfilled clinical criteria for PCA, were longitudinally assessed in our Alzheimer's Disease Research Centre and had stored DNA. These patients were matched for age at onset and sex to 37 cases of typical AD diagnosed by the NINCDS–ADRDA criteria, and 38 controls. The APOE4 allele frequency was compared using a chi–square test. Furthermore, the PCA cases were stratified by age at onset > 60 to access for possible interaction. There was no difference in years of education, or disease severity based on the MMSE, between the cases with PCA and typical AD. The mean age at onset was 60 years in both groups. The APOE4 allele frequency was 29.5% for PCA, 47.0% for typical AD, and 7.9% for controls. There was no difference in APOE 4 allele frequency between the cases of PCA and typical AD (p=0.47), or between PCA and controls (p=0.12). However, there was a difference between typical AD cases and normal controls (p =0.004). There was no difference when the PCA cases were stratified by age at onset > 60. We did not find any evidence for a difference in the APOE 4 allele frequency between PCA and typical AD.