levoleucovorin and allysine

α-Amino adipic semialdehyde (α-AASA) accumulates in body fluids from patients with pyridoxine-dependent epilepsy because of mutations in antiquitin (ALDH7A1) and serves as the biomarker for this condition. We have recently found that the urinary excretion of α-AASA was also increased in molybdenum cofactor and sulfite oxidase deficiencies. The seizures in pyridoxine-dependent epilepsy are caused by lowered cerebral levels of pyridoxal-5-phosphate (PLP), the bioactive form of pyridoxine (vitamin B(6)), which can be corrected by the supplementation of pyridoxine. The nonenzymatic trapping of PLP by the cyclic form of α-AASA is causative for the lowered cerebral PLP levels. We describe 2 siblings with clinically evident pyridoxine-responsive seizures associated with increased urinary excretion of α-AASA. Subsequent metabolic investigations revealed several metabolic abnormities, all indicative for molybdenum cofactor deficiency. Molecular investigations indeed revealed a known homozygous mutation in the MOCS2 gene. Based upon the clinically evident pyridoxine-responsive seizures in these 2 siblings, we recommend considering pyridoxine supplementation to patients affected with molybdenum cofactor or sulfite oxidase deficiencies.

Topics: 2-Aminoadipic Acid; Aldehyde Dehydrogenase; Brain; Child, Preschool; Consanguinity; Developmental Disabilities; Diagnosis, Differential; Diffusion Magnetic Resonance Imaging; DNA Mutational Analysis; Electroencephalography; Epilepsy; Exons; Female; Genetic Carrier Screening; Homozygote; Humans; Infant; Infant, Newborn; Leucovorin; Male; Metal Metabolism, Inborn Errors; Molybdoferredoxin; Neurologic Examination; Pyridoxal Phosphate; Pyridoxine; Sequence Analysis, DNA; Sulfurtransferases

Pyridoxine-dependent seizures (PDS) is an autosomal recessive disorder characterized by seizures presenting in neonates or infants up to 3 years of age which respond to pharmacological doses of pyridoxine. Alpha-aminoadipic semialdehyde dehydrogenase (antiquitin) deficiency was identified as an underlying defect in PDS characterized by accumulation of alpha-aminoadipic semialdehyde (alpha-AASA) as a specific marker and recently folinic acid-responsive seizures (FRS) were found to be allelic to PDS as the putative mutations were identified in the antiquitin gene (ALDH7A1). alpha-AASA is known to be in reversible equilibrium with its cyclic Shiff base, delta(1)-piperideine-6-carboxylate (P6C). Pipecolic acid (PA) is another biomarker often elevated but is not specific to PDS. Here, we developed the liquid chromatography-mass spectrometry (LC-MS/MS) method to determine the analytes of alpha-AASA, P6C and PA simultaneously in plasma and validated the assay using samples from confirmed cases. This approach eliminates the extra time and expense of running multiple assays and provides valuable information for the rapid diagnosis and treatment of patients with PDS and FRS which potentially could lead to a better outcome with improved quality of life. The stability study showed that alpha-AASA and P6C were unstable even at -20 degrees C. A careful sample handling with immediate freezing and testing is required for reliable result.

Topics: 2-Aminoadipic Acid; Aldehyde Dehydrogenase; Animals; Calibration; Cattle; Child; Child, Preschool; Chromatography, Liquid; Humans; Leucovorin; Mass Spectrometry; Picolinic Acids; Pipecolic Acids; Protein Stability; Seizures; Temperature; Time Factors