SMS and X-linked intellectual disability, Snyder type: Gain-of-function mutations in the C-terminus of ODC have been connected to Bachmann-Bupp Syndrome (BABS; OMIM #619075) (Bupp et al., 2018; Rajasekaran et al., 2021; VanSickle et al., 2021; Bupp et al., 2022) and loss-of-function mutations in spermine synthase are associated with Snyder-Robinson Syndrome (SRS) (Albert et al., 1993; Cason et al., 2003; Starks et al., 2018).