ATP6V1B2-related epileptic encephalopathy.

Epileptic disorders : international epilepsy journal with videotape 2020 Jun 01

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ATP6V1B2 encodes a subunit of the lysosomal transmembrane proton pump necessary for adequate functioning of several acid hydrolases. De novo monoallelic variants of this gene have been associated with two distinct phenotypes: Zimmermann-Laband syndrome 2 (ZLS2), an intellectual deficiency/multiple malformation syndrome, and dominant deafness onychodystrophy (DDOD), a multiple malformation syndrome without cognitive involvement. Epilepsy is not observed in DDOD, is variably present in ZLS2, but is a common feature in Zimmermann-Laband syndrome 1 (ZLS1) (caused by monoallelic pathogenic variants in KCNH1) and Zimmermann-Laband syndrome-like (ZLSL) (associated with KCNK4 variants). Herein, we report a case of an infant with severe epileptic encephalopathy with microcephaly and profound developmental delay, associated with a novel de novo loss-of-function variant in ATP6V1B2, diagnosed by whole-exome sequencing. This finding expands the spectrum of ATP6V1B2-associated disorders and adds ATP6V1B2 as a new member for the growing list of early-onset epileptic encephalopathy genes. [Published with video sequence].

Citation

Luciana Midori Inuzuka, Lúcia Inês Macedo-Souza, Bruno Della-Rippa, Fabiola Paoli Monteiro, Daniel de Souza Delgado, Luis Filipe Godoy, Luiza Ramos, Larissa Sampaio de Athayde Costa, Eliana Garzon, Fernando Kok. ATP6V1B2-related epileptic encephalopathy. Epileptic disorders : international epilepsy journal with videotape. 2020 Jun 01;22(3):317-322