MKS3/TMEM67 mutations are a major cause of COACH syndrome, a joubert syndrome related disorder with liver involvement

The acronym COACH defines an autosomal recessive condition of Cerebellar vermis hypo/ aplasia, Oligophrenia, congenital Ataxia, Coloboma and Hepatic fibrosis. Patients present the “molar tooth sign”, a midbrain-hindbrain malformation pathognomonic for Joubert Syndrome (JS) and Related Disorders (JSRDs). The main feature of COACH is congenital hepatic fibrosis (CHF), resulting from malformation of the embryonic ductal plate. CHF is invariably found also in Meckel syndrome (MS), a lethal ciliopathy already found to be allelic with JSRDs at the CEP290 and RPGRIP1L genes. Recently, mutations in the MKS3 gene (approved symbol TMEM67), causative of about 7% MS cases, have been detected in few Meckel-like and pure JS patients. Analysis of MKS3 in 14 COACH families identified mutations in 8 (57%). Features such as colobomas and nephronophthisis were found only in a subset of mutated cases. These data confirm COACH as a distinct JSRD subgroup with core features of JS plus CHF, which major gene is MKS3, and further strengthen gene-phenotype correlates in JSRDs

Pathogenic variants in STXBP1 and in genes for GABAa receptor subunities cause atypical rett/rett-like phenotypes

Rett syndrome (RTT) is a neurodevelopmental disorder, affecting 1 in 10,000 girls. Intellectual disability, loss of speech and hand skills with stereotypies, seizures and ataxia are recurrent features. Stringent diagnostic criteria distinguish classical Rett, caused by a MECP2 pathogenic variant in 95% of cases, from atypical girls, 40-73% carrying MECP2 variants, and rarely CDKL5 and FOXG1 alterations. A large fraction of atypical and RTT-like patients remain without genetic cause. Next Generation Sequencing (NGS) targeted to multigene panels/Whole Exome Sequencing (WES) in 137 girls suspected for RTT led to the identification of a de novo variant in STXBP1 gene in four atypical RTT and two RTT-like girls. De novo pathogenic variants-one in GABRB2 and, for first time, one in GABRG2-were disclosed in classic and atypical RTT patients. Interestingly, the GABRG2 variant occurred at low rate percentage in blood and buccal swabs, reinforcing the relevance of mosaicism in neurological disorders. We confirm the role of STXBP1 in atypical RTT/RTT-like patients if early psychomotor delay and epilepsy before 2 years of age are observed, indicating its inclusion in the RTT diagnostic panel. Lastly, we report pathogenic variants in Gamma-aminobutyric acid-A (GABAa) receptors as a cause of atypical/classic RTT phenotype, in accordance with the deregulation of GABAergic pathway observed in MECP2 defective in vitro and in vivo models

Effect of sodium phenylbutyrate/taurursodiol on tracheostomy/ventilation-free survival and hospitalisation in amyotrophic lateral sclerosis: long-term results from the CENTAUR trial

BACKGROUND: Coformulated sodium phenylbutyrate/taurursodiol (PB/TURSO) was shown to prolong survival and slow functional decline in amyotrophic lateral sclerosis (ALS). OBJECTIVE: Determine whether PB/TURSO prolonged tracheostomy/ventilation-free survival and/or reduced first hospitalisation in participants with ALS in the CENTAUR trial. METHODS: Adults with El Escorial Definite ALS ≤18 months from symptom onset were randomised to PB/ TURSO or placebo for 6 months. Those completing randomised treatment could enrol in an open-label extension (OLE) phase and receive PB/TURSO for ≤30 months. Times to the following individual or combined key events were compared in the originally randomised treatment groups over a period spanning trial start through July 2020 (longest postrandomisation follow-up, 35 months): death, tracheostomy, permanent assisted ventilation (PAV) and first hospitalisation. RESULTS: Risk of any key event was 47% lower in those originally randomised to PB/TURSO (n=87) versus placebo (n=48, 71% of whom received delayed-start PB/TURSO in the OLE phase) (HR=0.53; 95% CI 0.35 to 0.81; p=0.003). Risks of death or tracheostomy/PAV (HR=0.51; 95% CI 0.32 to 0.84; p=0.007) and first hospitalisation (HR=0.56; 95% CI 0.34 to 0.95; p=0.03) were also decreased in those originally randomised to PB/TURSO. CONCLUSIONS: Early PB/TURSO prolonged tracheostomy/PAV-free survival and delayed first hospitalisation in ALS. TRIAL REGISTRATION NUMBER: NCT03127514; NCT03488524

Safety and efficacy of oral levosimendan in people with amyotrophic lateral sclerosis (the REFALS study): a randomised, double-blind, placebo-controlled phase 3 trial

Background: There is an urgent unmet need for new therapies in amyotrophic lateral sclerosis. In a clinical study with healthy volunteers, levosimendan, a calcium sensitiser, was shown to improve neuromechanical efficiency and contractile function of the human diaphragm. We aimed to evaluate the safety and efficacy of oral levosimendan in people with amyotrophic lateral sclerosis, with a focus on respiratory function. Methods: The REFALS study is a randomised, double-blind, placebo-controlled phase 3 trial at 99 amyotrophic lateral sclerosis specialist centres in 14 countries worldwide. People with amyotrophic lateral sclerosis were eligible for participation if they were at least 18 years of age and had a sitting slow vital capacity (SVC) of 60–90% predicted. Participants were randomly assigned (2:1) by interactive web-response system to receive either levosimendan or placebo. The capsules for oral administration were identical in appearance to maintain blinding of participants and investigators. The primary endpoint was the change from baseline in supine SVC at 12 weeks, assessed as the percentage of predicted normal sitting SVC. The key secondary endpoint was the combined assessment of function and survival (CAFS) up to 48 weeks. Analyses were done in the intention-to-treat population, comprising all participants who were randomly assigned. This trial is registered at ClinicalTrials.gov (NCT03505021) and has been completed. An extension study (REFALS-ES; NCT03948178) has also been completed, but will be reported separately. Findings: Between June 21, 2018, and June 28, 2019, 871 people were screened for the study, of whom 496 were randomly assigned either levosimendan (n=329) or placebo (n=167). Participants were followed up between June 27, 2018 and June 26, 2020, for a median duration of 50·1 (IQR 37·5–51·1) weeks. The median duration of treatment was 47·9 (IQR 26·4–48·1) weeks. Change from baseline in supine SVC at 12 weeks was –6·73% with levosimendan and –6·99% with placebo, with no significant difference between the treatments (estimated treatment difference 0·26%, 95% CI –2·03 to 2·55, p=0·83). Similarly, at week 48, CAFS did not differ between treatment groups (least squares mean change from baseline 10·69, 95% CI –15·74 to 37·12; nominal p value=0·43). The most frequent adverse events were increased heart rate (106 [33%] of 326 receiving levosimendan vs 12 [7%] of 166 receiving placebo), fall (85 [26%] vs 48 [29%]), headache (93 [29%] vs 36 [22%]), and dyspnoea (59 [18%] vs 32 [19%]). 33 (10%) participants allocated levosimendan and 20 (12%) assigned placebo died during the trial, mainly due to respiratory failure or progression of amyotrophic lateral sclerosis. Interpretation: Levosimendan was not superior to placebo in maintaining respiratory function in a broad population with amyotrophic lateral sclerosis. Although levosimendan was generally well tolerated, increased heart rate and headache occurred more frequently with levosimendan than with placebo. The possibility of a clinically relevant subgroup of responsive individuals requires further evaluation. Funding: Orion Corporation

PURA-Related Developmental and Epileptic Encephalopathy Phenotypic and Genotypic Spectrum

Background and Objectives Purine-rich element-binding protein A (PURA) gene encodes Pur-α, a conserved protein essential for normal postnatal brain development. Recently, a PURA syndrome characterized by intellectual disability, hypotonia, epilepsy, and dysmorphic features was suggested. The aim of this study was to define and expand the phenotypic spectrum of PURA syndrome by collecting data, including EEG, from a large cohort of affected patients. Methods Data on unpublished and published cases were collected through the PURA Syndrome Foundation and the literature. Data on clinical, genetic, neuroimaging, and neurophysiologic features were obtained. Results A cohort of 142 patients was included. Characteristics of the PURA syndrome included neonatal hypotonia, feeding difficulties, and respiratory distress. Sixty percent of the patients developed epilepsy with myoclonic, generalized tonic-clonic, focal seizures, and/or epileptic spasms. EEG showed generalized, multifocal, or focal epileptic abnormalities. Lennox-Gastaut was the most common epilepsy syndrome. Drug refractoriness was common: 33.3% achieved seizure freedom. We found 97 pathogenic variants in PURA without any clear genotype-phenotype associations. Discussion The PURA syndrome presents with a developmental and epileptic encephalopathy with characteristics recognizable from neonatal age, which should prompt genetic screening. Sixty percent have drug-resistant epilepsy with focal or generalized seizures. We collected more than 90 pathogenic variants without observing overt genotype-phenotype associations

Effect of sodium phenylbutyrate/taurursodiol on tracheostomy/ventilation-free survival and hospitalisation in amyotrophic lateral sclerosis: long-term results from the CENTAUR trial

BackgroundCoformulated sodium phenylbutyrate/taurursodiol (PB/TURSO) was shown to prolong survival and slow functional decline in amyotrophic lateral sclerosis (ALS).ObjectiveDetermine whether PB/TURSO prolonged tracheostomy/ventilation-free survival and/or reduced first hospitalisation in participants with ALS in the CENTAUR trial.MethodsAdults with El Escorial Definite ALS ≤18 months from symptom onset were randomised to PB/ TURSO or placebo for 6 months. Those completing randomised treatment could enrol in an open-label extension (OLE) phase and receive PB/TURSO for ≤30 months. Times to the following individual or combined key events were compared in the originally randomised treatment groups over a period spanning trial start through July 2020 (longest postrandomisation follow-up, 35 months): death, tracheostomy, permanent assisted ventilation (PAV) and first hospitalisation.ResultsRisk of any key event was 47% lower in those originally randomised to PB/TURSO (n=87) versus placebo (n=48, 71% of whom received delayed-start PB/TURSO in the OLE phase) (HR=0.53; 95% CI 0.35 to 0.81; p=0.003). Risks of death or tracheostomy/PAV (HR=0.51; 95% CI 0.32 to 0.84; p=0.007) and first hospitalisation (HR=0.56; 95% CI 0.34 to 0.95; p=0.03) were also decreased in those originally randomised to PB/TURSO.ConclusionsEarly PB/TURSO prolonged tracheostomy/PAV-free survival and delayed first hospitalisation in ALS.Trial registration numberNCT03127514; NCT03488524