The reversion of FPR2 under-expression in the long-term (> 1 year) severe OSA patients on CPAP as compared with that in the treatment-naïve OSA group but not in those after > 6-month CPAP home treatment in the 9 selected patients indicate that FPR2 insufficiency induced by chronic IHR in OSA may require a longer time to recovery. The gene discussed is FPR2; the disease is obstructive sleep apnea syndrome.