1. KCNT2-Related Disorders: Phenotypes, Functional, and Pharmacological Properties
- Author
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Cioclu, M.C., Mosca, I., Ambrosino, P., Puzo, D., Bayat, A., Wortmann, S.B., Koch, J., Strehlow, V., Shirai, K., Matsumoto, N., Sanders, S.J., Michaud, V., Legendre, M., Riva, A., Striano, P., Muhle, H., Pendziwiat, M., Lesca, G., Mangano, G.D., Nardello, R., Lemke, J.R., Møller, R.S., Soldovieri, M.V., Kamsteeg, E.J., Rubboli, G., Taglialatela, M., Cioclu, M.C., Mosca, I., Ambrosino, P., Puzo, D., Bayat, A., Wortmann, S.B., Koch, J., Strehlow, V., Shirai, K., Matsumoto, N., Sanders, S.J., Michaud, V., Legendre, M., Riva, A., Striano, P., Muhle, H., Pendziwiat, M., Lesca, G., Mangano, G.D., Nardello, R., Lemke, J.R., Møller, R.S., Soldovieri, M.V., Kamsteeg, E.J., Rubboli, G., and Taglialatela, M.
- Abstract
Item does not contain fulltext, OBJECTIVE: Pathogenic variants in KCNT2 are rare causes of developmental epileptic encephalopathy (DEE). We herein describe the phenotypic and genetic features of patients with KCNT2-related DEE, and the in vitro functional and pharmacological properties of KCNT2 channels carrying 14 novel or previously untested variants. METHODS: Twenty-five patients harboring KCNT2 variants were investigated: 12 were identified through an international collaborative network, 13 were retrieved from the literature. Clinical data were collected and included in a standardized phenotyping sheet. Novel variants were detected using exome sequencing and classified using ACMG criteria. Functional and pharmacological studies were performed by whole-cell electrophysiology in HEK-293 and SH-SY5Y cells. RESULTS: The phenotypic spectrum encompassed: (a) intellectual disability/developmental delay (21/22 individuals with available information), ranging from mild to severe/profound; (b) epilepsy (15/25); (c) neurological impairment, with altered muscle tone (14/22); (d) dysmorphisms (13/20). Nineteen pathogenic KCNT2 variants were found (9 new, 10 reported previously): 16 missense, 1 in-frame deletion of a single amino acid, 1 nonsense, and 1 frameshift. Among tested variants, 8 showed gain-of-function (GoF), and 6 loss-of-function (LoF) features when expressed heterologously in vitro. Quinidine and fluoxetine blocked all GoF variants, whereas loxapine and riluzole activated some LoF variants while blocking others. INTERPRETATION: We expanded the phenotypic and genotypic spectrum of KCNT2-related disorders, highlighting novel genotype-phenotype associations. Pathogenic KCNT2 variants cause GoF or LoF in vitro phenotypes, and each shows a unique pharmacological profile, suggesting the need for in vitro functional and pharmacological investigation to enable targeted therapies based on the molecular phenotype. ANN NEUROL 2023;94:332-349.
- Published
- 2023