Objective  The aim of this study was to observe the mRNA expression of DNA methyl-transferase(DNMT) and methyl-CpG binding protein(MeCP) in the peripheral blood mononuclear cells from GPP patients, and to explore the potential role of DNA methylation in the pathogenesis of GPP.

  Methods  Clinical data of 9 GPP patients admitted or hospitalized at the Department of Dermatology of Peking Union Medical College Hospital from December 2015 to December 2016 were retrospectively collected. Ten healthy people who underwent a physical examination in the same hospital during the same period were randomly selected as the control group; their age and gender were matched with those of GPP patients. Peripheral blood mononuclear cells were isolated from 10 ml blood of the elbow median vein using density gradient centrifugation. Total RNA was extracted from peripheral blood mononuclear cells by Trizol method; mRNA expression levels of DNMT1, DNMT3a, DNMT3b, MBD1, MBD2, MBD3, MBD4, and MeCP2 were detected by real-time PCR. The correlation of age and GPP severity with the expression level of these mRNAs was observed and analyzed.

  Results  Compared with the healthy subjects, the relative expressions of DNMT3a, DNMT3b, MBD1, MBD2, and MBD4 mRNA in peripheral blood mononuclear cells from GPP patients were higher than those from the healthy controls DNMT3a:0.000 17(0.000 06, 0.001 15) vs. 0.000 03(0.000 02, 0.000 04), DNMT3b 0.000 04± 0.000 02 vs. 0.000 02±0.000 01, MBD1 0.001 01±0.000 45 vs. 0.000 46±0.000 15, MBD2 0.002 61±0.000 39 vs. 0.001 85±0.000 52; and MBD4 0.004 29±0.001 60 vs. 0.001 57±0.000 55, all P < 0.05. There was no correlation between age and GPP severity with the mRNA expression of the above factors (all P > 0.05).

  Conclusions  Methylation related regulatory genes are abnormally expressed in GPP patients, and do not correlate with age or the disease severity.