AR and obstructive sleep apnea syndrome: We found that Interleukin1 receptor 2 (IL-1 R2) hypomethylation and Androgen receptor (AR) hypermethylation may constitute an important determinant of disease severity, while Natriuretic peptide receptor2 (NPR2) hypomethylation and speckled protein 140 (SP140) hypermethylation may provide a biomarker for vulnerability to excessive daytime sleepiness in OSA [81].