KCNQ2 R144 variants cause neurodevelopmental disability with language impairment and autistic features without neonatal seizures through a gain-of-function mechanism

Francesco Miceli, Charissa Millevert, Maria Virginia Soldovieri, Ilaria Mosca, Paolo Ambrosino, Lidia Carotenuto, Dewi Schrader, Hyun Kyung Lee, James Riviello, William Hong, Sarah Risen, Lisa Emrick, Hitha Amin, Dorothée Ville, Patrick Edery, Julitta de Bellescize, Vincent Michaud, Julien Van-Gils, Cyril Goizet, Marjolein H WillemsenTjitske Kleefstra, Rikke S Møller, Allan Bayat, Orrin Devinsky, Tristan Sands, G Christoph Korenke, Gerhard Kluger, Heather C Mefford, Eva Brilstra, Gaetan Lesca, Mathieu Milh, Edward C Cooper, Maurizio Taglialatela, Sarah Weckhuysen

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Abstract

BACKGROUND: Prior studies have revealed remarkable phenotypic heterogeneity in KCNQ2-related disorders, correlated with effects on biophysical features of heterologously expressed channels. Here, we assessed phenotypes and functional properties associated with KCNQ2 missense variants R144W, R144Q, and R144G. We also explored in vitro blockade of channels carrying R144Q mutant subunits by amitriptyline.

METHODS: Patients were identified using the RIKEE database and through clinical collaborators. Phenotypes were collected by a standardized questionnaire. Functional and pharmacological properties of variant subunits were analyzed by whole-cell patch-clamp recordings.

FINDINGS: Detailed clinical information on fifteen patients (14 novel and 1 previously published) was analyzed. All patients had developmental delay with prominent language impairment. R144Q patients were more severely affected than R144W patients. Infantile to childhood onset epilepsy occurred in 40%, while 67% of sleep-EEGs showed sleep-activated epileptiform activity. Ten patients (67%) showed autistic features. Activation gating of homomeric Kv7.2 R144W/Q/G channels was left-shifted, suggesting gain-of-function effects. Amitriptyline blocked channels containing Kv7.2 and Kv7.2 R144Q subunits.

INTERPRETATION: Patients carrying KCNQ2 R144 gain-of-function variants have developmental delay with prominent language impairment, autistic features, often accompanied by infantile- to childhood-onset epilepsy and EEG sleep-activated epileptiform activity. The absence of neonatal seizures is a robust and important clinical differentiator between KCNQ2 gain-of-function and loss-of-function variants. The Kv7.2/7.3 channel blocker amitriptyline might represent a targeted treatment.

FUNDING: Supported by FWO, GSKE, KCNQ2-Cure, Jack Pribaz Foundation, European Joint Programme on Rare Disease 2020, the Italian Ministry for University and Research, the Italian Ministry of Health, the European Commission, the University of Antwerp, NINDS, and Chalk Family Foundation.

Original languageEnglish
Article number104130
Pages (from-to)1-15
JournalEBioMedicine
Volume81
DOIs
Publication statusPublished - Jul 2022

Keywords

  • Amitriptyline
  • Autistic Disorder
  • Epilepsy
  • Gain of Function Mutation
  • Humans
  • Infant, Newborn
  • Infant, Newborn, Diseases
  • KCNQ2 Potassium Channel/genetics
  • Language Development Disorders
  • Seizures
  • Autism
  • KCNQ2
  • Gain-of-function
  • Developmental and epileptic encephalopathy

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