Structural mapping of GABRB3 variants reveals genotype-phenotype correlations.

Area of Science:

• Neurogenetics
• Epilepsy Research
• Developmental Neuroscience

Background:

• Pathogenic variants in the GABRB3 gene are linked to diverse neurodevelopmental disorders, including epileptic encephalopathies and intellectual disability (ID).
• Understanding the precise genotype-phenotype correlations is crucial for accurate diagnosis and management.

Purpose of the Study:

• To deepen the understanding of phenotypes associated with GABRB3 variants.
• To investigate genotype-phenotype correlations within a large cohort of affected individuals.

Main Methods:

• Analysis of electro-clinical data from a large international cohort, including novel and previously published cases with GABRB3 variants.
• Mapping missense variants onto the 3D structure of the GABRB3 subunit.
• Investigating clinical phenotypes related to specific structural domains.

Main Results:

• Characterization of 71 individuals with GABRB3 variants, revealing a wide phenotypic spectrum.
• Correlation of variant location with phenotype: extracellular domain variants associated with generalized epilepsy and mild-to-moderate ID.
• Variants in the pore-lining transmembrane and extracellular domains linked to focal epilepsy and severe ID.

Conclusions:

• Established genotype-phenotype correlations for GABRB3 variants provide valuable insights for genetic counseling and treatment.
• Further research into functional differences may elucidate the basis of observed phenotypic variability.