In the wet AMD group, the serum concentration of YKL‐40 (1251.84 ± 118.94 pg·mL−1) was markedly higher than that in the healthy subjects (751.19 ± 73.79 pg·mL−1, P = 0.0090) (Fig. 1A). The gene discussed is CHI3L1; the disease is age-related macular degeneration.