DAO and kidney disorder: The level of D-Alanine increases up to 82 μM in patients with kidney diseases (Hesaka et al. 2019; Kimura et al. 2016, 2023) or 100 μM in Dao-deficient rodents (Gonda et al. 2023; Karakawa et al. 2013; Miyoshi et al. 2009).