Genome-wide DNA methylation study in Chinese Systemic Lupus Erythematosus

Epigenetic alternations in addition to genetic factors are important contributors to the pathogenesis of Systemic Lupus Erythematosus (SLE). Recent studies revealed that aberrant changes in DNA methylation occur in SLE patients, and potentially contributes to the pathogenesis. Using genome-wide DNA methylation microarray, the Illumina Infinium HumanMethylation450 BeadChip, we compared the DNA methylation level of white blood cells between Chinese female SLE patients with that of healthy controls. There was no difference in global levels of DNA methylation between SLE patients and controls. However, we identified 36 CpG sites with differential loss of DNA methylation and 8 CpG sites with differential gain of DNA methylation, representing 26 genes and 7 genes respectively. Surprisingly, nearly half of the hypomethylated CpG sites were located in the CpG shores, which implicated the functional importance of loss of DNA methylation in the CpG shores in SLE. The DNA methylation data of 12 SLE was compared with 10 sex- and ethnic-matched healthy controls. All the patients are self-reported to be Chinese and all met the criteria of the American College of Rheumatology for SLE diagnosis. Genomic DNA was bisulfite converted and DNA methylation was measured by HumanMethylation450 BeadChip.