Pyridoxine dependent seizures (PDS) is a genetic disorder characterized by seizures presenting in neonates or infants up to 3 years of age, which respond to pharmacological dose of pyridoxine (vitamin B6). Alpha-aminoadipic semialdehyde dehydrogenase (antiquitin) deficiency in lysine degradation pathway was identified as an underlying defect. PDS is characterized by accumulation of α-aminoadipic semialdehyde (α-AASA) and piperideine-6-carboxylate (P6C) in body fluids (plasma, urine, cerebrospinal fluid) and can be used as biochemical markers of the disease. Recently, folinic acid-responsive seizures, a form of seizures that respond to treatment with folinic acid are found due to alpha-aminoadipic semialdehyde dehydrogenase (antiquitin) deficiency and mutations in the ALDH7A1 gene. This method simultaneously determines α-AASA and P6C in plasma and serum for diagnosis of PDS and folinic acid-responsive seizures (FRS).