Journal
EBIOMEDICINE
Volume 81, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.ebiom.2022.104130
Keywords
KCNQ2; Gain-of-function; Amitriptyline; Autism; Developmental and epileptic encephalopathy
Funding
- FWO [1861419N, G041821N]
- Queen Elisabeth Medical Foundation for Neurosciences (GSKE)
- KCNQ2-Cure
- Jack Pribaz Foundation
- KCNQ2e.v.
- European Joint Programme on Rare Disease JTC 2020 (TreatKCNQ)
- Italian Ministry for University and Research (MIUR) [PRIN 2017ALCR7C, PRIN 2017YH3SXK]
- Italian Ministry of Health [RF-2019-12370491]
- European Commission H2020 [UNICOM - 875299]
- NINDS [NS49119, NS108874]
- Chalk Family Foundation
- Miles Family Fund
- University of Antwerp (BOF DOCPRO4- project) [42329]
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This study investigated the phenotypes and functional properties associated with KCNQ2 missense variants R144W, R144Q, and R144G. The results revealed that these variants were correlated with developmental delay, language impairment, epilepsy, and autistic features. Amitriptyline was found to block channels carrying the R144Q variant.
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. Copyright (C) 2022 The Authors. Published by Elsevier B.V.
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