APOE genotype in the diagnosis of Alzheimer's disease in patients with cognitive impairment.

Background: Although an association between the apolipoprotein E (APOE) ε4 allele and increased risk of Alzheimer's disease (AD) is established, the utility of APOE genotyping in the clinical diagnosis of AD is still under investigation.

Methods: Medical records of 89 patients with cognitive impairment and APOE genotype data underwent a retrospective review.

Results: Comparison of age, age at onset, education, Mini-Mental State Examination, months of follow-up, and family history of dementia did not reveal statistical difference among the patients with different APOE genotypes. The APOE ε4 carriers had a higher percentage of AD diagnoses after a median 16 months follow-up than non-APOE ε4 carriers. The APOE ε4 designation had a high sensitivity and high positive predictive value for the diagnosis of AD but a low negative predictive value and specificity.

Conclusions: The APOE genotyping may be helpful in diagnosing AD especially in patients presenting with atypical features or early age of onset of dementia.