Succinate semialdehyde dehydrogenase (SSADH; ALDH5A1) deficiency, a rare metabolic disorder that disrupts the normal degradation of GABA, gives rise to a highly heterogeneous neurological phenotype ranging from mild to very severe. The nature of the mutation has so far been reported in patients from
Biochemical and molecular characterization of 18 patients with pyridoxine-dependent epilepsy and mutations of the antiquitin (ALDH7A1) gene
β Scribed by Barbara Plecko; Karl Paul; Eduard Paschke; Sylvia Stoeckler-Ipsiroglu; Eduard Struys; Cornelis Jakobs; Hans Hartmann; Thomas Luecke; Matteo di Capua; Christoph Korenke; Christiane Hikel; Elke Reutershahn; Michael Freilinger; Fritz Baumeister; Friedrich Bosch; Wolfgang Erwa
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 299 KB
- Volume
- 28
- Category
- Article
- ISSN
- 1059-7794
No coin nor oath required. For personal study only.
β¦ Synopsis
Communicated by Arnold Munnich
Patients with pyridoxine dependent epilepsy (PDE) present with early-onset seizures resistant to common anticonvulsants. According to the benefit of pyridoxine (vitamin B 6 ) and recurrence of seizures on pyridoxine withdrawal, patients so far have been classified as having definite, probable, or possible PDE. Recently, PDE has been shown to be caused by a defect of a-amino adipic semialdehyde (AASA) dehydrogenase (antiquitin) in the cerebral lysine degradation pathway. The accumulating compound piperideine-6-carboxylic acid (P6C) was shown to inactivate pyridoxalphosphate (PLP) by a Knoevenagel condensation. Pipecolic acid (PA) and AASA are markedly elevated in urine, plasma, and cerebrospinal fluid (CSF) and thus can be used as biomarkers of the disease. We have investigated 18 patients with neonatal seizure onset, who have been classified as having definite (11), probable (four), or possible (three) PDE. All patients had elevated PA and AASA in plasma (and urine) while on treatment with individual dosages of pyridoxine. Within this cohort, molecular analysis identified 10 novel mutations (six missense mutations, one nonsense mutation, two splice site mutations) within highly conserved regions of the antiquitin gene. Seven mutations were located in exonic sequences and two in introns 7 and 17. Furthermore, a novel deletion of exon 7 was identified. Two of the 36 alleles investigated require further investigation. A known mutation (p.Glu399Gln) was found with marked prevalence, accounting for 12 out of 36 alleles (33%) within our cohort. Pyridoxine withdrawal is no longer needed to establish the diagnosis of ''definite'' PDE. Administration of pyridoxine in PDE may not only correct secondary PLP deficiency, but may also lead to a reduction of AASA (and P6C) as presumably toxic compounds.
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