Abstract
Objective: Pathogenic variants in KCNB1, encoding the voltage-gated potassium channel KV2.1, are associated with developmental and epileptic encephalopathy (DEE). Previous functional studies on a limited number of KCNB1 variants indicated a range of molecular mechanisms by which variants affect channel function, including loss of voltage sensitivity, loss of ion selectivity, and reduced cell-surface expression. Methods: We evaluated a series of 17 KCNB1 variants associated with DEE or other neurodevelopmental disorders (NDDs) to rapidly ascertain channel dysfunction using high-throughput functional assays. Specifically, we investigated the biophysical properties and cell-surface expression of variant KV2.1 channels expressed in heterologous cells using high-throughput automated electrophysiology and immunocytochemistry–flow cytometry. Results: Pathogenic variants exhibited diverse functional defects, including altered current density and shifts in the voltage dependence of activation and/or inactivation, as homotetramers or when coexpressed with wild-type KV2.1. Quantification of protein expression also identified variants with reduced total KV2.1 expression or deficient cell-surface expression. Interpretation: Our study establishes a platform for rapid screening of KV2.1 functional defects caused by KCNB1 variants associated with DEE and other NDDs. This will aid in establishing KCNB1 variant pathogenicity and the mechanism of dysfunction, which will enable targeted strategies for therapeutic intervention based on molecular phenotype. ANN NEUROL 2019;86:899–912.
Original language | English (US) |
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Pages (from-to) | 899-912 |
Number of pages | 14 |
Journal | Annals of neurology |
Volume | 86 |
Issue number | 6 |
DOIs | |
State | Published - Dec 1 2019 |
Funding
This work was supported by funding from NIH National Institute of Neurological Disorders and Stroke grants R01 NS053792 (J.A.K.), U54 NS108874 (A.L.G.), and K08 NS097633 (E.M.G.), the Ann & Robert H. Lurie Children's Hospital of Chicago Precision Medicine Initiative (J.J.M., J.B.O., S.N.M.), and the Pediatric Physician‐Scientist Research Award (S.N.M.). A.T. is supported by Scripps Research Translational Institute and an NIH National Center for Advancing Translation Sciences Clinical and Translational Science Award (5 UL1 TR001114). A.P. was supported by the Translational Research Program, Boston Children's Hospital. S.K.K. is supported by a predoctoral fellowship from the American Epilepsy Society. We thank the patients and their families for their cooperation; and T. Abramova, R. Desai, N. Hawkins, T. Thaxton, and A. Huffman for technical assistance.
ASJC Scopus subject areas
- Neurology
- Clinical Neurology