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Epilepsy due to 20q13.33 subtelomere deletion masquerading as pyridoxine-dependent epilepsy

Authors

  • Heather C. Mefford,

    1. Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, Washington
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  • Joseph Cook,

    1. Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, Washington
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  • Sidney M. Gospe Jr.

    Corresponding author
    1. Division of Pediatric Neurology, Departments of Neurology and Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, Washington
    • Seattle Children's Hospital 4800 Sand Point Way NE Neurology, B-5552 Seattle, WA 98105.
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  • How to Cite this Article: Mefford HC, Cook J, Gospe SM. 2012. Epilepsy due to 20q13.33 subtelomere deletion masquerading as pyridoxine-dependent epilepsy. Am J Med Genet Part A 158A: 3190–3195.

Abstract

A cause of antiepileptic medication resistant seizures presenting in neonates and young infants is pyridoxine-dependent epilepsy (PDE), an organic aciduria, which is due to recessive mutations in the ALDH7A1 gene, resulting in deficiency of antiquitin. Since the discovery of molecular basis of this disorder, a few patients have been reported with a similar clinical phenotype but without evidence of antiqutin dysfunction. We report on a patient who had carried a clinical diagnosis of PDE for 7 years, but who was than shown to have normal ALDH7A1 sequencing and the absence of biomarkers characteristic of this familial epilepsy. Array comparative genomic hybridization (CGH) demonstrated a 1.5-Mb terminal deletion of the long arm of chromosome 20, which included deletion of the KCNQ2 and CHRNA4 genes, both of which have been associated with specific epilepsy syndromes. We suggest that this boy's neonatal epilepsy and neurodevelopmental disabilities are secondary to this deletion and that his clinical response to pyridoxine was coincidental. This patient's history emphasizes the utility of array CGH in the evaluation of children with epilepsy of unknown etiology. © 2012 Wiley Periodicals, Inc.

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