KCNT1 gain of function in 2 epilepsy phenotypes is reversed by quinidine

Authors

  • Carol J. Milligan PhD,

    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
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  • Melody Li BSc,

    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
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  • Elena V. Gazina PhD,

    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
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  • Sarah E. Heron PhD,

    1. School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
    2. Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
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  • Umesh Nair BSc,

    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
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  • Chantel Trager BSc,

    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
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  • Christopher A. Reid PhD,

    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
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  • Anu Venkat MD,

    1. Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
    2. Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA
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  • Donald P. Younkin MD,

    1. Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA
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  • Dennis J. Dlugos MD,

    1. Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
    2. Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA
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  • Slavé Petrovski PhD,

    1. Center for Human Genome Variation, Duke University School of Medicine, Durham, NC
    2. Department of Medicine, Austin Health and Royal Melbourne Hospital, University of Melbourne, Austin Hospital, Heidelberg, Australia
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  • David B. Goldstein PhD,

    1. Center for Human Genome Variation, Duke University School of Medicine, Durham, NC
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  • Leanne M. Dibbens PhD,

    1. School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
    2. Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
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  • Ingrid E. Scheffer MBBS, PhD,

    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
    2. Epilepsy Research Centre, Department of Medicine, University of Melbourne, Melbourne, Australia
    3. Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia
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  • Samuel F. Berkovic MD,

    1. Epilepsy Research Centre, Department of Medicine, University of Melbourne, Melbourne, Australia
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  • Steven Petrou PhD

    Corresponding author
    1. Ion Channels and Disease Group, Epilepsy Division, Florey Institute of Neuroscience and Mental Health, Parkville, Australia
    2. Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Australia
    3. Centre for Neural Engineering, University of Melbourne, Melbourne, Australia
    • Address correspondence to Dr Petrou, Florey Institute of Neuroscience and Mental Health, Kenneth Myer Building, 30 Royal Parade, Parkville, Victoria, Australia, 3010. E-mail: spetrou@unimelb.edu.au

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Abstract

Objective

Mutations in KCNT1 have been implicated in autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) and epilepsy of infancy with migrating focal seizures (EIMFS). More recently, a whole exome sequencing study of epileptic encephalopathies identified an additional de novo mutation in 1 proband with EIMFS. We aim to investigate the electrophysiological and pharmacological characteristics of hKCNT1 mutations and examine developmental expression levels.

Methods

Here we use a Xenopus laevis oocyte-based automated 2-electrode voltage clamp assay. The effects of quinidine (100 and 300μM) are also tested. Using quantitative reverse transcriptase polymerase chain reaction, the relative levels of mouse brain mKcnt1 mRNA expression are determined.

Results

We demonstrate that KCNT1 mutations implicated in epilepsy cause a marked increase in function. Importantly, there is a significant group difference in gain of function between mutations associated with ADNFLE and EIMFS. Finally, exposure to quinidine significantly reduces this gain of function for all mutations studied.

Interpretation

These results establish direction for a targeted therapy and potentially exemplify a translational paradigm for in vitro studies informing novel therapies in a neuropsychiatric disease. Ann Neurol 2014;75:581–590

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