BDNF level is reduced in the glaucomatous retina (Pease et al., 2000; Quigley et al., 2000; Fabiani et al., 2016) as well as in several brain areas of AD (Connor et al., 1997; Michalski and Fahnestock, 2003; Peng et al., 2005), thus contributing to advancing the hypothesis that a scarce availability of BDNF renders neurons more vulnerable. The gene discussed is BDNF; the disease is Alzheimer disease.