DNA Methylation Changes in Intron 1 of in Japanese Schizophrenia Subjects.

A hypothesis for schizophrenia (SCZ) called the "microglia hypothesis" has been suggested. In SCZ, expression of () mRNA is higher in leukocytes than in healthy individuals. Here, the methylation rates of four CpG sites in intron 1 that may bind important transcription factors and the correlation between the methylation rate and mRNA expression were determined. We compared the methylation rates in SCZ patients and age-matched controls ( = 50 each). SCZ patients had significantly lower methylation rates of CpG 2 (17.0 ± 6.7 vs. 20.2 ± 5.0; = 0.02) and CpG 3 (23.8 ± 8.2 vs. 28.1 ± 6.2; = 0.01). The average methylation rate (15.3 ± 5.2 vs. 17.6 ± 3.9; = 0.009) was also lower. A significant negative correlation was found between mRNA expression and the methylation rate of CpG 2 ( = -0.252, = 0.012). SCZ susceptibility markers may include low methylation at intron 1 and increased mRNA levels. Our pilot study requires validation with higher numbers of participants and with other myeloid cell types.