ALDH7A1 and hyperprolinemia type 2: Regarding the implications of our findings for the pathophysiological understanding of HPII, it is interesting to note that for PDE-ALDH7A1, the analogous P6C-adduct biomarkers were found to have epileptogenic potential in a zebrafish model system and could also be detected in brain tissue of PDE-ALDH7A1 patients.