Interestingly, in a study of 54 primary canine OSA subjects [63], two clades were identified that differed significantly with regard to expression of genes involved in the cytokine pathway, including changes in expression regarding VCAM1, CDKN1A, SERPING1, IFIT2, ICAM2, TLR3, TNFRSF11A and ISG15 [63]. Here, ISG15 is linked to obstructive sleep apnea syndrome.