Search

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 analyse the electro-clinical features and the functional effects of GABRA1-variants to establish genotype–phenotype correlations. Methods Genetic and electro-clinical data of 27 individuals (22 unrelated and 2 families) harbouring 20 different GABRA1 variants were collected and accompanied with functional analysis of 19 variants. Results Individuals in this cohort could be assigned into different clinical subgroups based on the functional effect of their variant and its structural position within the GABRA1 subunit. A homogenous phenotype with mild cognitive impairment and infantile-onset epilepsy (focal seizures, fever sensitivity and EEG posterior epileptiform discharges) was described for variants in the extra-cellular domain and the small transmembrane loops. These variants displayed loss-of-function (LoF) effects and the patients generally had a favourable outcome. A more severe phenotype was associated with variants in the pore-forming transmembrane helices. These variants displayed either gain-of-function (GoF) or LoF effects. GoF-variants were associated with severe early-onset neurodevelopmental disorders, including early infantile developmental and epileptic encephalopathy. Interpretation Our data expand the genetic and phenotypic spectrum of GABRA1-epilepsies and permit to delineate specific sub-phenotypes for LoF and GoF variants, though the heterogeneity of phenotypes and variants. Generally, variants in the transmembrane helices cause more severe phenotypes, in particular GoF variants. These findings establish the basis for a better understanding of the patho-mechanism and precision medicine approach in, 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 analyse the electro-clinical features and the functional effects of GABRA1-variants to establish genotype-phenotype correlations.METHODS: Genetic and electro-clinical data of 27 individuals (22 unrelated and 2 families) harbouring 20 different GABRA1 variants were collected and accompanied with functional analysis of 19 variants.RESULTS: Individuals in this cohort could be assigned into different clinical subgroups based on the functional effect of their variant and its structural position within the GABRA1 subunit. A homogenous phenotype with mild cognitive impairment and infantile-onset epilepsy (focal seizures, fever sensitivity and EEG posterior epileptiform discharges) was described for variants in the extra-cellular domain and the small transmembrane loops. These variants displayed loss-of-function (LoF) effects and the patients generally had a favourable outcome. A more severe phenotype was associated with variants in the pore-forming transmembrane helices. These variants displayed either gain-of-function (GoF) or LoF effects. GoF-variants were associated with severe early-onset neurodevelopmental disorders, including early infantile developmental and epileptic encephalopathy.INTERPRETATION: Our data expand the genetic and phenotypic spectrum of GABRA1-epilepsies and permit to delineate specific sub-phenotypes for LoF and GoF variants, though the heterogeneity of phenotypes and variants. Generally, variants in the transmembrane helices cause more severe phenotypes, in particular GoF variants. These findings establish the basis for a better understanding of the patho-mechanism and precision medicine approach in GABRA1-related di

Gene variants that dysregulate signaling through the RAS-MAPK pathway cause cardiofaciocutaneous syndrome (CFCS), a rare multi-system disorder. Infantile epileptic spasms syndrome (IESS) and other forms of epilepsy are among the most serious complications. To investigate clinical presentation, treatment outcomes, and genotype-phenotype associations in CFCS patients with IESS, molecular genetics and clinical neurological history were reviewed across two large clinical research cohorts (n = 180). IESS presented in 18/180 (10%) cases, including 16 patients with BRAF variants and 2 with MAP2K1 variants. Among IESS patients with BRAF variants, 16/16 (100%) had sequence changes affecting the protein kinase domain (exons 11-16), although only 57% of total BRAF variants occurred in this domain. Clinical onset of spasms occurred at a median age of 5.4 months (range: 1-24 months). Among 13/18 patients whose IESS resolved with anti-seizure medications, 10 were treated with ACTH and/or vigabatrin. A substantial majority of CFCS patients with IESS subsequently developed other epilepsy types (16/18; 89%). In terms of neurodevelopmental outcomes, gross motor function and verbal communication were more limited in patients with a history of IESS compared to those without IESS. These findings can inform clinical neurological care guidelines for CFCS and development of relevant pre-clinical models for severe epilepsy phenotypes.