Epileptic Disorders
MENUATP6V1B2-related epileptic encephalopathy Volume 22, numéro 3, June 2020
- Mots-clés : ATP6V1B2, Zimmermann-Laband syndrome 1, Zimmermann-Laband syndrome 2, epileptic encephalopathy, dominant deafness onychodystrophy, epilepsy
- DOI : 10.1684/epd.2020.1166
- Page(s) : 317-22
- Année de parution : 2020
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].