Since then, more neurotrophic factors, including brain-derived neurotrophic factor (BDNF; LaVail et al., 1992), ciliary neurotrophic factor (CNTF; Unoki and LaVail, 1994), glial cell line-derived neurotrophic factor (GDNF; Buch et al., 2006), and pigment epithelium-derived factor (PEDF; Miyazaki et al., 2003), have been found to effectively counter retinal degeneration. The gene discussed is GDNF; the disease is retinal degeneration.