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Diagnostic Services

Genetics Lab


Pyridoxine-Dependent Seizures Known Mutation Analysis

The patients with pyridoxine-dependent seizures (PDS) classically present with neonatal seizures, unresponsive to conventional anticonvulsant therapy but which can be controlled with pyridoxine monotherapy. Less commonly, later-onset cases present through the second to third year of life. In PDS, seizures are typically prolonged but can also include self-limiting partial, generalized, atonic, or myoclonic seizures or infantile spasms. Although most PDS patients show a rapid response to pyridoxine treatment, some show a transient response to common anticonvulsants or a poor initial response to pyridoxine.

PDS, a rare autosomal recessive disease, is caused by a deficiency of the enzyme alpha-aminoadipic semialdehyde dehydrogenase, encoded by the ALDH7A1 gene. Mutations in the ALDH7A1 gene and subsequent enzyme deficiency lead to an accumulation of alpha-aminoadipic semialdehyde (AASA) and a deficiency of the active form of vitamin B6, which is needed as a cofactor for many reactions in the central nervous system including metabolism of neurotransmitters such as dopamine, glutamate, GABA and serotonin.

Mutations in the ALDH7A1 gene account for ~95% of patients with PDS who have documented elevation of AASA. All individuals studied in families with the classic neonatal presentation have at least one mutation in the ALDH7A1 gene. The detection rate for individuals with atypical presentation of pyridoxine dependent seizures is not known.

Test Name: Pyridoxine-Dependent Seizures Known Mutation Analysis
Test Code:
Test Description:
Polymerase Chain Reaction (PCR) followed by sequence analysis of the ALDH7A1 gene for known mutations.
This test is used for carrier testing at-risk relatives and prenatal testing for confirmed carriers. Mutations must be known.
Related Tests: Maternal Cell Contamination - DNA  
Maternal DNA is compared to fetal DNA to evaluate whether maternal cell contamination of the fetal sample has occurred.

Pyridoxine-Dependent Seizures Sequencing Analysis  
DNA sequence analysis of all 18 exons and flanking regions of the ALDH7A1 gene

Clinical Links: Pyridoxine-Dependent Seizures GeneReview
Mon - Fri
Turnaround Time:
1-2 weeks
PCR followed by Sequencing
Reference Range:
Interpretive report will be provided
Consent Form:
Sample Requirements: Type
Whole blood: 1-3 mL in EDTA (purple top) or ACD (yellow top).
DNA: 5 micrograms extracted DNA.
Prenatal samples: 2 T-25 flasks

Do not spin. Keep at room temperature. Send cultured fetal cells in appropriate media.

Room temperature via overnight shipping. Blood samples must be processed within 3 days of collection
Samples Received:
Monday - Friday 8am - 5pm PST
Special Considerations:
For prenatal testing, mutations must be known and maternal cell contamination testing is required (ordered separately).
Please e-mail Lab Client Services ( or call at 206-987-2617 with any billing questions
CPT Code:
Please e-mail Lab Client Services ( or call at 206-987-2617 with any billing questions