CTCF and Alzheimer disease: Sanchez-Mut et al. have identified PM20D1 (localized within the PARK16 locus and encoding for the peptidase M20-domain containing protein one enzyme with both hydrolase and peptidase activities; N-fatty acyl amino acid synthase/hydrolase) as being a methylation and expression quantitative trait locus (mQTL) coupled to an AD-risk associated haplotype, which displays enhancer-like characteristics and contacts the PM20D1 promoter via a haplotype-dependent, CTCF (CCCTC-binding-) transcription-factor-mediated chromatin loop [27].