Using whole genome DNA methylation analysis, we have identified interleukin 1 receptor type 2 hypomethylation and androgen receptor hypermethylation as an important determinant of disease severity of OSA, and natriuretic peptide 2 hypomethylation and speckled protein 140 hypermethylation as a biomarker for vulnerability to excessive daytime sleepiness (EDS) in OSA [16]. The gene discussed is AR; the disease is obstructive sleep apnea syndrome.