Consistent with GnRH concentrations in plasma, the overall GnRH saliva concentrations in KC subjects were significantly lower (77.7 pg/mL, IQR 32.3–158.0 pg/mL) compared to control subjects (118.6 pg/mL, IQR 67.7–203.6 pg/mL, p = 0.0007, Figure 2A). Here, GNRH1 is linked to keratoconus.