GABBR1 and obstructive sleep apnea syndrome: None of the three SNPs in the leptin receptor (LEPR), the matrix metallopeptidase 9 (MMP9), and the Gamma-aminobutyric acid type B receptor subunit 1 (GABBR1), the association of which with OSA diagnosis was validated in their study, was associated with other non-OSA clinical traits once they controlled for multiple testing (5).