COMT and schizophrenia: Apart from MMP9, hypomethylations have also been detected in other genes, such as AluY A3 CpG (Li et al., 2019), promoter of GRIN2B (Fachim et al., 2019), CpG2 and CpG3 in TREM2 intron 1 (Yoshino et al., 2017), CpG sites in FAM63B and intergenic region on chromosome 16, CpG sites in TBC1D22A (Sugawara et al., 2018), and COMT (Nour El Huda et al., 2018) in schizophrenia compared with controls.