Understanding paralogous epilepsy-associated GABA receptor variants: Clinical implications, mechanisms, and potential pitfalls.

Recent discoveries have revealed that genetic variants in γ-aminobutyric acid type A (GABA) receptor subunits can lead to both gain-of-function (GOF) and loss-of-function (LOF) receptors. GABA receptors, however, have a pseudosymmetrical pentameric assembly, and curiously diverse functional outcomes have been reported for certain homologous variants in paralogous genes (paralogous variants). To investigate this, we assembled a cohort of 11 individuals harboring paralogous M1 proline missense variants in , , and Seven mutations (α1, α1, β2, β3, β3, γ2, and γ2) in α1β2/3γ2 receptors were analyzed using electrophysiological examinations and molecular dynamics simulations.

Distinct neurodevelopmental and epileptic phenotypes associated with gain- and loss-of-function GABRB2 variants.

Background: Variants in GABRB2, encoding the β2 subunit of the γ-aminobutyric acid type A (GABA) receptor, can result in a diverse range of conditions, ranging from febrile seizures to severe developmental and epileptic encephalopathies. However, the mechanisms underlying the risk of developing milder vs more severe forms of disorder remain unclear. In this study, we conducted a comprehensive genotype-phenotype correlation analysis in a cohort of individuals with GABRB2 variants.

Correlations of receptor desensitization of gain-of-function GABRB3 variants with clinical severity.

Genetic variants associated with developmental and epileptic encephalopathies have been identified in the GABRB3 gene that encodes the β3 subunit of GABAA receptors. Typically, variants alter receptor sensitivity to GABA resulting in either gain- or loss-of-function, which correlates with patient phenotypes. However, it is unclear how another important receptor property, desensitization, contributes to the greater clinical severity of gain-of-function variants.

GABA receptors in epilepsy: Elucidating phenotypic divergence through functional analysis of genetic variants.

Normal brain function requires a tightly regulated balance between excitatory and inhibitory neurotransmissions. γ-Aminobutyric acid type A (GABA) receptors represent the major class of inhibitory ion channels in the mammalian brain. Dysregulation of these receptors and/or their associated pathways is strongly implicated in the pathophysiology of epilepsy.

GABRA1-Related Disorders: From Genetic to Functional Pathways.

Objective: Variants in GABRA1 have been associated with a broad epilepsy spectrum, ranging from genetic generalized epilepsies to developmental and epileptic encephalopathies. However, our understanding of what determines the phenotype severity and best treatment options remains inadequate. We therefore aimed to analyze the electroclinical features and the functional effects of GABRA1 variants to establish genotype-phenotype correlations.