Previous studies have shown that leukocyte telomere length (LTL) is shorter[131] and SIRT1 protein levels are lower in OSA patients compared with healthy subjects.[132] A few studies reported recovery in blood levels of SIRT1 protein following successful nasal CPAP treatment of OSA.[132] One clinical trial which investigated the effect of MAD treatment on circulating LTL and SIRT1 protein levels in peripheral blood mononuclear cells with 40 moderate to severe OSA patients for 3 months reported that OSA patients had lower LTL and SIRT1 protein levels compared with healthy subjects. The gene discussed is SIRT1; the disease is obstructive sleep apnea syndrome.