While GDE2 activity is disrupted in neurodegenerative diseases affecting cognition, and Gde2KO mice display behavioral deficits associated with hippocampal dysfunction (Nakamura et al., 2021; Westerhaus et al., 2022; Daudelin et al., 2024), the role of GDE2 in the hippocampus has not been addressed. Here, GDPD5 is linked to neurodegenerative disease.