The case of a patient who presented with neonatal seizures unresponsive to conventional antiepile... more The case of a patient who presented with neonatal seizures unresponsive to conventional antiepileptic drugs and pyridoxine is reported. The baby girl was subsequently treated with pyridoxal 5'-phosphate (PLP) on day 20 of life, and showed rapid seizure control and normal development, with only mildly abnormal liver function tests at the current age of 6 years. Sequencing of the pyridox(am)ine 5'-phosphate oxidase (PNPO) gene revealed a heterozygous insertion of a single base in exon 7. The second allele was found to be normal although the patient may carry a mutation in another gene of the vitamin B6 pathway. Follow-up at 6 years of age showed a seizure-free young girl (on 42 mg/kg/day PLP) with normal development but mild elevation of liver function tests. A high index of suspicion for metabolic disease must be kept in mind with neonatal seizures unresponsive to conventional treatment.
In the mouse, neurotransmitter metabolism can be regulated by modulation of the synthesis of pyri... more In the mouse, neurotransmitter metabolism can be regulated by modulation of the synthesis of pyridoxal 5'-phosphate and failure to maintain pyridoxal phosphate (PLP) levels results in epilepsy. This study of five patients with neonatal epileptic encephalopathy suggests that the same is true in man. Cerebrospinal fluid and urine analyses indicated reduced activity of aromatic L-amino acid decarboxylase and other PLP-dependent enzymes. Seizures ceased with the administration of PLP, having been resistant to treatment with pyridoxine, suggesting a defect of pyridox(am)ine 5'-phosphate oxidase (PNPO). Sequencing of the PNPO gene identified homozygous missense, splice site and stop codon mutations. Expression studies in Chinese hamster ovary cells showed that the splice site (IVS3-1g>a) and stop codon (X262Q) mutations were null activity mutations and that the missense mutation (R229W) markedly reduced pyridox(am)ine phosphate oxidase activity. Maintenance of optimal PLP level...
Seventy-five percent of patients with pyridoxine-dependent epilepsy (PDE) due to Antiquitin (ATQ)... more Seventy-five percent of patients with pyridoxine-dependent epilepsy (PDE) due to Antiquitin (ATQ) deficiency suffer from developmental delay and/or intellectual disability (IQ < 70) despite seizure control. An observational study showed that adjunct treatment with a lysine-restricted diet is safe, results in partial normalization of lysine intermediates in body fluids, and may have beneficial effects on seizure control and psychomotor development. In analogy to the NICE guideline process, the international PDE Consortium, an open platform uniting scientists and clinicians working in the field of this metabolic epilepsy, during four workshops (2010-2013) developed a recommendation for a lysine-restricted diet in PDE, with the aim of standardizing its implementation and monitoring of patients. Additionally, a proposal for a further observational study is suggested. (1) All patients with confirmed ATQ deficiency are eligible for adjunct treatment with lysine-restricted diet, unless treatment with pyridoxine alone has resulted in complete symptom resolution, including normal behavior and development. (2) Lysine restriction should be started as early as possible; the optimal duration remains undetermined. (3) The diet should be implemented and the patient be monitored according to these recommendations in order to assure best possible quality of care and safety. The implementation of this recommendation will provide a unique and a much needed opportunity to gather data with which to refine the recommendation as well as improve our understanding of outcomes of individuals affected by this rare disease. We therefore propose an international observational study that would utilize freely accessible, online data sharing technologies to generate more evidence.
The case of a patient who presented with neonatal seizures unresponsive to conventional antiepile... more The case of a patient who presented with neonatal seizures unresponsive to conventional antiepileptic drugs and pyridoxine is reported. The baby girl was subsequently treated with pyridoxal 5'-phosphate (PLP) on day 20 of life, and showed rapid seizure control and normal development, with only mildly abnormal liver function tests at the current age of 6 years. Sequencing of the pyridox(am)ine 5'-phosphate oxidase (PNPO) gene revealed a heterozygous insertion of a single base in exon 7. The second allele was found to be normal although the patient may carry a mutation in another gene of the vitamin B6 pathway. Follow-up at 6 years of age showed a seizure-free young girl (on 42 mg/kg/day PLP) with normal development but mild elevation of liver function tests. A high index of suspicion for metabolic disease must be kept in mind with neonatal seizures unresponsive to conventional treatment.
In the mouse, neurotransmitter metabolism can be regulated by modulation of the synthesis of pyri... more In the mouse, neurotransmitter metabolism can be regulated by modulation of the synthesis of pyridoxal 5'-phosphate and failure to maintain pyridoxal phosphate (PLP) levels results in epilepsy. This study of five patients with neonatal epileptic encephalopathy suggests that the same is true in man. Cerebrospinal fluid and urine analyses indicated reduced activity of aromatic L-amino acid decarboxylase and other PLP-dependent enzymes. Seizures ceased with the administration of PLP, having been resistant to treatment with pyridoxine, suggesting a defect of pyridox(am)ine 5'-phosphate oxidase (PNPO). Sequencing of the PNPO gene identified homozygous missense, splice site and stop codon mutations. Expression studies in Chinese hamster ovary cells showed that the splice site (IVS3-1g>a) and stop codon (X262Q) mutations were null activity mutations and that the missense mutation (R229W) markedly reduced pyridox(am)ine phosphate oxidase activity. Maintenance of optimal PLP level...
Seventy-five percent of patients with pyridoxine-dependent epilepsy (PDE) due to Antiquitin (ATQ)... more Seventy-five percent of patients with pyridoxine-dependent epilepsy (PDE) due to Antiquitin (ATQ) deficiency suffer from developmental delay and/or intellectual disability (IQ < 70) despite seizure control. An observational study showed that adjunct treatment with a lysine-restricted diet is safe, results in partial normalization of lysine intermediates in body fluids, and may have beneficial effects on seizure control and psychomotor development. In analogy to the NICE guideline process, the international PDE Consortium, an open platform uniting scientists and clinicians working in the field of this metabolic epilepsy, during four workshops (2010-2013) developed a recommendation for a lysine-restricted diet in PDE, with the aim of standardizing its implementation and monitoring of patients. Additionally, a proposal for a further observational study is suggested. (1) All patients with confirmed ATQ deficiency are eligible for adjunct treatment with lysine-restricted diet, unless treatment with pyridoxine alone has resulted in complete symptom resolution, including normal behavior and development. (2) Lysine restriction should be started as early as possible; the optimal duration remains undetermined. (3) The diet should be implemented and the patient be monitored according to these recommendations in order to assure best possible quality of care and safety. The implementation of this recommendation will provide a unique and a much needed opportunity to gather data with which to refine the recommendation as well as improve our understanding of outcomes of individuals affected by this rare disease. We therefore propose an international observational study that would utilize freely accessible, online data sharing technologies to generate more evidence.
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