Mutations in the PEPD gene result in Prolidase Deficiency, which is characterized by accumulation of imidodipeptides, the di- and tri-peptides containing proline or hydroxyproline. Encoded by the PEPD gene located at 19q12-q13.11, prolidase is a ubiquitous cytosolic enzyme that catalyzes hydrolysis of oligopeptides with a C-terminal proline or hydroxyproline residues. It plays an essential role in the later stage of degradation of endogenous and dietary proteins rich in proline and hydroxyproline.
Mutations in PEPD can be identified using next generation sequencing or targeted variant analysis. Deletions have also been observed in patients with Prolidase Deficiency, and deletion and duplication testing are available.