Alpha Aminoadipic Semialdehyde (Urine)

Urine Alpha aminoadipic semialdehyde (AASA) is useful for diagnosing pyridoxine-dependent seizures (PDS) and folinic acid-responsive seizures (FRS). Elevation of AASA can also occur in molybdenum cofactor deficiency. Urine AASA may also be used for assessment of Variants of Uncertain Significance (VUS) identified during genetic testing (e.g. Next Generation Sequencing or Capillary Sequencing Testing). Pyridoxine dependent seizures is a genetic disorder characterized by seizures in neonates or infants up to 3 years of age, which in general, respond to a pharmacologic dose of pyridoxine (vitamin B6). AASA dehyrogenase (antiquin) deficiency is the underlying defect. Piperideine-6-Carboxylate (P6C) is the cyclic isomer of AASA and the equilibrium between P6C and AASA is PH dependent. P6P reacts with pyridoxal 5'-phosphate and leads to deficiency of this cofactor. Folinic responsive seizures and PDS are allelic, and caused mutations in the ALDH7A1 gene. Biochemical testing should be done prior to gene sequencing, and can be done regardless of pyridoxine therapy.