DKK4 and ablepharon macrostomia syndrome: In addition, Lu et al. identified four cytokines including IGFBP6 (insulin-like growth factor binding protein 6), Dkk4 (dickkopf WNT signaling pathway inhibitor 4), SAA1 (serum amyloid A1), and IL-17RA (interleukin 17 receptor A), which might predict AMS susceptibility in a low-altitude environment (Lu et al., 2016).