Discrepancies between apolipoprotein E phenotyping and genotyping in the elderly

We estimated the frequencies of phenotype (isoelectric focusing; IEF) vs, g enotype (PCR/Hhal) discordance in a sample of an aged population (> 65 year s). Both phenotype and genotype techniques have been used in the study of a polipoprotein E (apoE) polymorphism in 125 elderly subjects. The discordance between phenotype and genotype was unresolved in 11 (8.8%) of the 125 unrelated subjects studied. We observed a significant associatio n between the presence of the E4 allele and both Alzheimer's disease (chi ( 2) = 13, p<0.001) and increased cholesterol concentration (Mann Whitney, p< 0.03). These relationships were not affected by the techniques used. Our results indicate that transcriptional modulation and post-transductiona l modifications in normal ageing and in aged-related diseases may explain i n part discrepancies between gene analysis and protein characterisation.