SPECIFICITY, SENSITIVITY, AND PREDICTIVE VALUE OF APOLIPOPROTEIN-E GENOTYPING FOR SPORADIC ALZHEIMERS-DISEASE

Background We aimed to determine the specificity, sensitivity, and pre dictive value of apolipoprotein E(APOE) genotyping in 67 consecutive P atients with clinical diagnoses of sporadic Alzheimer's disease (AD) w ho underwent necropsy. Methods We studied patients who attended the Du ke Memory Disorders Clinic and were diagnosed as having probable AD. T hese patients were followed up until they died, APOE genotyping was do ne during life in most cases, but in some brain tissue obtained at nec ropsy was used. Members of known AD families were excluded. Findings A fter neuropathological examination 57 (85%) of 67 of our patients were confirmed as having AD including all 43 who had at least one APOE-is an element of 4 allele. None of the patients found not to have AD carr ied an is an element of 4 allele, In this series, the specificity of t he is an element of 4 allele was 100%, the sensitivity 75%, the positi ve predictive value 100%, and the negative predictive value 42%. In th is necropsy-confirmed series, the is an element of 4/is an element of 4 genotype predicted AD with 100% accuracy. The is an element of 3/is an element of 4 and is an element of 2/is an element of 4 genotypes we re also unexpectedly highly specific for AD. Interpretation Data from hundreds of necropsy-confirmed non-AD patients in other longitudinal n ecropsy series will allow the predictive value oi APOE genotypes to be assessed with useful confidence limits.