To obtain a comprehensive DNA methylation signature specific for the epidermal component of psoriasis and to analyze methylation changes during therapy, we performed genome-wide DNA methylation profiling of epidermal cells from 12 patients undergoing narrow-band UVB phototherapy and 12 corresponding healthy controls. A distinct DNA methylation pattern was seen in psoriasis compared to controls. An overall hypomethylation was found in psoriasis and 3665 methylation variable positions were identified. The DNA methylation pattern was reversed at the end of phototherapy in patients with clinical response.
Bisulphite converted DNA from the 47 samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip.