NSUN2 and Alzheimer disease: However, while quantitative real-time PCR (QPCR) analysis did not show a significant difference in the levels of NSun2 mRNA in the hippocampal formation, prefrontal cortex NSun2 mRNA levels were significantly higher in AD brains, suggesting a compensatory mechanism in the prefrontal cortex, a brain area that degenerates later in the disease process (Supplementary Fig. 3, online resource).