APOE hypermethylation is associated with autism spectrum disorder in a Chinese population

Abnormal apolipoprotein E (APOE) methylation has been demonstrated to be associated with Alzheimer's disease, which may have overlapping mechanisms with autism spectrum disorder (ASD). Thus, the purpose of the present study was to assess the possible link between APOE methylation and ASD. Genomic DNA was extracted from peripheral blood and subjected to a methylation assay. SYBR green-based quantitative methylation-specific polymerase chain reaction analysis was used to measure APOE methylation in 62 pediatric patients with ASD and 73 age-matched healthy subjects. The APOE methylation in each sample was expressed as a percentage of methylation of a reference (PMR). The results indicated that APOE methylation in pediatric patients with ASD was significantly higher than that in the healthy controls (median PMR, 33 vs. 11%; P=2.36×10^-10). Receiver operating characteristic curve demonstrated that PMR of 15.4% was the optimal cut-off for predicting ASD (area under curve, 0.817; sensitivity, 93.5%; specificity, 72.6%; P=2.36×10^-10). In summary, the present results indicated that APOE hypermethylation in peripheral blood DNA may be used as a diagnostic biomarker for ASD.