KCNQ2 encephalopathy: A case due to a de novo deletion

Carlotta Spagnoli, Grazia Gabriella Salerno, Alessandro Iodice, Daniele Frattini, Francesco Pisani, Carlo Fusco

Research output: Contribution to journalArticle

Abstract

KCNQ2 encephalopathy is characterized by severely abnormal EEG, neonatal-onset epilepsy and developmental delay. It is caused by mutations (typically missense) in the KCNQ2 gene, encoding the voltage gated potassium channel Kv7.2 and leading to a negative-dominant effect. We present one case experiencing recurrent neonatal seizures with changing hemispheres of origin, reminiscent of epilepsy of infancy with migrating focal seizures. At 9. months of age the patient is still seizure-free on carbamazepine, although he is developing a spastic-dystonic tetraplegia with severe dysphagia. He harbors a de novo deletion (c.913_915del [p.Phe305del)]), only described once in a couple of severely affected twins, and leading to the deletion of a phenylalanine residue in the pore domain of the channel. In conclusion, our case is the second described with encephalopathy due to this specific deletion (the one and only deletion so far reported in KCNQ2 encephalopathy). Thus, deletion is a newly described mechanism highlighting how not only missense mutations but also deletions in the channel hot spots can lead to a severe phenotype. Furthermore he presented ictal EEG features similar to epilepsy of infancy with migrating focal seizures not previously described.

Original languageEnglish
JournalBrain and Development
DOIs
Publication statusAccepted/In press - Feb 3 2017

Keywords

  • Deletion
  • EEG
  • Genetic
  • KCNQ2 encephalopathy
  • Neonatal-onset epilepsy

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Developmental Neuroscience
  • Clinical Neurology

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