Keywords: ALDH7A1; Alpha-aminoadipic acid semialdehyde; CSF; CSF pipecolic acid; CSF-PA; P-PA; P6C; PA; PDE; PDE caused by ALDH7A1 genetic defect; PDE-ALDH7A1; Pipecolic acid; Pyridoxine dependent epilepsy; U-PA; alpha-aminoadipic acid semialdehyde; alpha-aminoadipic semialdehyde dehydrogenase; cerebral spinal fluid; pipecolic acid; piperidine 6-carboxylic acid; plasma pipecolic acid; pyridoxine dependent epilepsy; urine pipecolic acid; α-AASA; α-AASAD.