The overall GnRH plasma concentrations in KC subjects were significantly lower (median, interquartile range (IQR): 67.4 ng/mL, IQR 52.6–87.7 ng/mL) compared to control subjects (100.1 ng/mL, IQR 72.3–177.8 ng/mL, p < 0.0001, Figure 1A). Here, GNRH1 is linked to keratoconus.