TLR6 and obstructive sleep apnea syndrome: DNA methylation over 28 cytosine-phosphate-guanine (CpG) sites of the TLR2 promoter region and 3 CpG sites of the TLR6 gene body, and their protein expressions were measured by using pyrosequencing and ELISA methods in 18 heathy subjects (HS) and 58 patients with severe OSA (divided into 18 non-EDS and 40 EDS group).