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. METHODS: Genetic and electroclinical data of 27 individuals (22 unrelated and 2 families) harboring 20 different GABRA1 variants were collected and accompanied by 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 electroencephalographic posterior epileptiform discharges) was described for variants in the extracellular domain and the small transmembrane loops. These variants displayed loss-of-function (LoF) effects, and the patients generally had a favorable 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 delineation of specific subphenotypes for LoF and GoF variants, through 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 pathomechanism and a precision medicine approach in GABRA1-related disorders. Further studies in larger populations are needed to provide a conclusive genotype-phenotype correlation. ANN NEUROL 2023.

[Treatment of status epilepticus in children and adults].

This review finds that, in children and adults with epilepsy, there are several treatment options. Multiple antiseizure medications are available and in case of drug-resistant epilepsy, a non-pharmacological approach is recommended, including epilepsy surgery, vagus nerve stimulation, or ketogenic diet treatment. The aim of the treatment is to avoid further seizures, but also to avoid negative cognitive, psychological, and social consequences of epilepsy.

Elp2 mutations perturb the epitranscriptome and lead to a complex neurodevelopmental phenotype.

Intellectual disability (ID) and autism spectrum disorder (ASD) are the most common neurodevelopmental disorders and are characterized by substantial impairment in intellectual and adaptive functioning, with their genetic and molecular basis remaining largely unknown. Here, we identify biallelic variants in the gene encoding one of the Elongator complex subunits, ELP2, in patients with ID and ASD. Modelling the variants in mice recapitulates the patient features, with brain imaging and tractography analysis revealing microcephaly, loss of white matter tract integrity and an aberrant functional connectome. We show that the Elp2 mutations negatively impact the activity of the complex and its function in translation via tRNA modification. Further, we elucidate that the mutations perturb protein homeostasis leading to impaired neurogenesis, myelin loss and neurodegeneration. Collectively, our data demonstrate an unexpected role for tRNA modification in the pathogenesis of monogenic ID and ASD and define Elp2 as a key regulator of brain development.

Choroid plexus hyperplasia and chromosome 9p gains.

Choroid plexus hyperplasia leading to communicating hydrocephalus is a rare disorder with only 24 patients reported so far in the literature. Furthermore, genetic information is only available for six of these cases: In one patient the condition was associated with trisomy 9p, in one patient with trisomy 9 mosaicism and in three patients with tetrasomy 9p. Here, we describe four additional patients with choroid plexus hyperplasia leading to various levels of hydrocephalus, and gain of the entire chromosome 9p region: Three with trisomy 9p and one with tetrasomy 9p. The three patients with trisomy 9p were siblings. Normal karyotypes were identified in the lymphocytes of the parents. Likely one of the parents is a mosaic for a cell line with trisomy 9p in the gonads. We demonstrate the importance of correctly diagnosing choroid plexus hyperplasia as the cause of hydrocephalus in patients with chromosome 9p gain since ventriculoperitoneal shunting is likely to fail due to intolerable formation of ascites.

[Possible side effects from HPV vaccination in Denmark].

HPV vaccination offers protection against ~70% of cervical cancers, however, serious concerns have been raised about the possible side effects from HPV vaccination. Studies have found no increased risk of neurologic disease, autoimmune disorder, thromboembolic disease, postural orthostatic tachycardia syndrome, or complex regional pain syndrome in HPV-vaccinated persons compared to unvaccinated persons. Affected individuals should undergo a proper clinical examination to ensure a correct diagnosis and treatment, because symptoms might arise due to a somatic, psychiatric or functional disorder.