Structural mapping of GABRB3 variants reveals genotype-phenotype correlations

Johannesen, Katrine M.; Iqbal, Sumaiya; Guazzi, Milena; Mohammadi, Nazanin A.; Perez-Palma, Eduardo; Schaefer, Elise; De Saint Martin, Anne; Abiwarde, Marie Therese; McTague, Amy; Pons, Roser; Piton, Amelie; Kurian, Manju A.; Ambegaonkar, Gautam; Firth, Helen; Sanchis-Juan, Alba; et. al.


Purpose: Pathogenic variants in GABRB3 have been associated with a spectrum of phenotypes from severe developmental disorders and epileptic encephalopathies to milder epilepsy syndromes and mild intellectual disability (ID). In this study, we analyzed a large cohort of individuals with GABRB3 variants to deepen the phenotypic understanding and investigate genotype-phenotype correlations. Methods: Through an international collaboration, we analyzed electro-clinical data of unpublished individuals with variants in GABRB3, and we reviewed previously published cases. All missense variants were mapped onto the 3-dimensional structure of the GABRB3 subunit, and clinical phenotypes associated with the different key structural domains were investigated. Results: We characterized 71 individuals with GABRB3 variants, including 22 novel subjects, expressing a wide spectrum of phenotypes. Interestingly, phenotypes correlated with structural locations of the variants. Generalized epilepsy, with a median age at onset of 12 months, and mild-to-moderate ID were associated with variants in the extracellular domain. Focal epilepsy with earlier onset (median: age 4 months) and severe ID were associated with variants in both the pore-lining helical transmembrane domain and the extracellular domain. Conclusion: These genotype-phenotype correlations will aid the genetic counseling and treatment of individuals affected by GABRB3-related disorders. Future studies may reveal whether functional differences underlie the phenotypic differences. (C) 2021 American College of Medical Genetics and Genomics. Published by Elsevier Inc. All rights reserved.

Más información

Título según WOS: ID WOS:000797902900012 Not found in local WOS DB
Título de la Revista: GENETICS IN MEDICINE
Volumen: 24
Número: 3
Editorial: Elsevier Science Inc.
Fecha de publicación: 2022
Página de inicio: 681
Página final: 693


Notas: ISI