Genome sequencing and comprehensive rare-variant analysis of 465 families with neurodevelopmental disorders.

Despite significant progress in unraveling the genetic causes of neurodevelopmental disorders (NDDs), a substantial proportion of individuals with NDDs remain without a genetic diagnosis after microarray and/or exome sequencing. Here, we aimed to assess the power of short-read genome sequencing (GS), complemented with long-read GS, to identify causal variants in participants with NDD from the National Institute for Health and Care Research (NIHR) BioResource project. Short-read GS was conducted on 692 individuals (489 affected and 203 unaffected relatives) from 465 families. Additionally, long-read GS was performed on five affected individuals who had structural variants (SVs) in technically challenging regions, had complex SVs, or required distal variant phasing. Causal variants were identified in 36% of affected individuals (177/489), and a further 23% (112/489) had a variant of uncertain significance after multiple rounds of re-analysis. Among all reported variants, 88% (333/380) were coding nuclear SNVs or insertions and deletions (indels), and the remainder were SVs, non-coding variants, and mitochondrial variants. Furthermore, long-read GS facilitated the resolution of challenging SVs and invalidated variants of difficult interpretation from short-read GS. This study demonstrates the value of short-read GS, complemented with long-read GS, in investigating the genetic causes of NDDs. GS provides a comprehensive and unbiased method of identifying all types of variants throughout the nuclear and mitochondrial genomes in individuals with NDD.

L-serine treatment in patients with GRIN-related encephalopathy: a phase 2A, non-randomized study.

GRIN-related disorders are rare developmental encephalopathies with variable manifestations and limited therapeutic options. Here, we present the first non-randomized, open-label, single-arm trial (NCT04646447) designed to evaluate the tolerability and efficacy of L-serine in children with GRIN genetic variants leading to loss-of-function. In this phase 2A trial, patients aged 2-18 years with GRIN loss-of-function pathogenic variants received L-serine for 52 weeks. Primary end points included safety and efficacy by measuring changes in the Vineland Adaptive Behavior Scales, Bayley Scales, age-appropriate Wechsler Scales, Gross Motor Function-88, Sleep Disturbance Scale for Children, Pediatric Quality of Life Inventory, Child Behavior Checklist and the Caregiver-Teacher Report Form following 12 months of treatment. Secondary outcomes included seizure frequency and intensity reduction and EEG improvement. Assessments were performed 3 months and 1 day before starting treatment and 1, 3, 6 and 12 months after beginning the supplement. Twenty-four participants were enrolled (13 males/11 females, mean age 9.8 years, SD 4.8), 23 of whom completed the study. Patients had GRIN2B, GRIN1 and GRIN2A variants (12, 6 and 5 cases, respectively). Their clinical phenotypes showed 91% had intellectual disability (61% severe), 83% had behavioural problems, 78% had movement disorders and 58% had epilepsy. Based on the Vineland Adaptive Behavior Composite standard scores, nine children were classified as mildly impaired (cut-off score > 55), whereas 14 were assigned to the clinically severe group. An improvement was detected in the Daily Living Skills domain (P = 0035) from the Vineland Scales within the mild group. Expressive (P = 0.005), Personal (P = 0.003), Community (P = 0.009), Interpersonal (P = 0.005) and Fine Motor (P = 0.031) subdomains improved for the whole cohort, although improvement was mostly found in the mild group. The Growth Scale Values in the Cognitive subdomain of the Bayley-III Scale showed a significant improvement in the severe group (P = 0.016), with a mean increase of 21.6 points. L-serine treatment was associated with significant improvement in the median Gross Motor Function-88 total score (P = 0.002) and the mean Pediatric Quality of Life total score (P = 0.00068), regardless of severity. L-serine normalized the EEG pattern in five children and the frequency of seizures in one clinically affected child. One patient discontinued treatment due to irritability and insomnia. The trial provides evidence that L-serine is a safe treatment for children with GRIN loss-of-function variants, having the potential to improve adaptive behaviour, motor function and quality of life, with a better response to the treatment in mild phenotypes.

Expanding the phenotypic spectrum of TRAPPC11-related muscular dystrophy: 25 Roma individuals carrying a founder variant.

BACKGROUND: Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of genetically determined muscle disorders. TRAPPC11-related LGMD is an autosomal-recessive condition characterised by muscle weakness and intellectual disability. METHODS: A clinical and histopathological characterisation of 25 Roma individuals with LGMD R18 caused by the homozygous TRAPPC11 c.1287+5G>A variant is reported. Functional effects of the variant on mitochondrial function were investigated. RESULTS: The c.1287+5G>A variant leads to a phenotype characterised by early onset muscle weakness, movement disorder, intellectual disability and elevated serum creatine kinase, which is similar to other series. As novel clinical findings, we found that microcephaly is almost universal and that infections in the first years of life seem to act as triggers for a psychomotor regression and onset of seizures in several individuals with TRAPPC11 variants, who showed pseudometabolic crises triggered by infections. Our functional studies expanded the role of TRAPPC11 deficiency in mitochondrial function, as a decreased mitochondrial ATP production capacity and alterations in the mitochondrial network architecture were detected. CONCLUSION: We provide a comprehensive phenotypic characterisation of the pathogenic variant TRAPPC11 c.1287+5G>A, which is founder in the Roma population. Our observations indicate that some typical features of golgipathies, such as microcephaly and clinical decompensation associated with infections, are prevalent in individuals with LGMD R18.

Outbreak of Enterovirus Infection with Neurological Presentations in a Pediatric Population in Northern Spain: A Clinical Observational Study.

OBJECTIVE: The study aimed to describe the cases of neurological disease related to the outbreak of enterovirus (EV) in three regions in Northern Spain during 2016. MATERIALS AND METHODS: Multicenter retrospective observational study. Clinical, radiological, and microbiological data were analyzed from patients younger than 15 years with confirmed EV-associated neurological disease admitted to 10 hospitals of Asturias, Cantabria, and Castile and Leon between January 1 and December 31, 2016. RESULTS: Fifty-five patients were included. Median age was 24 months (interquartile range = 18.5 months). Fifteen patients were classified as aseptic meningitis (27.3%). In total, 37 cases presented brainstem encephalitis (67.3%), 25 of them due to EV-A71 with excellent prognosis (84.6% asymptomatic 2 months following the onset). Three cases of acute flaccid myelitis (5.5%) by EV-D68 were reported and presented persistent paresis 2 months following the onset. Microbiological diagnosis by reverse transcriptase polymerase chain reaction was performed in all cases, finding EV in cerebrospinal fluid in meningitis, but not in brainstem encephalitis and acute flaccid myelitis, where EV was found in respiratory or rectal samples. Step therapy was administrated with intravenous immunoglobulin (IVIG; 32.7%), methylprednisolone (10%), and plasmapheresis (3.6%). Four patients received fluoxetine (7.3%). Twenty patients needed to be admitted to pediatric intensive care unit (36.4%). CONCLUSION: Clinical, microbiological, and radiological diagnosis is essential in outbreaks of EV neurological disease, taking into account that it can be difficult to identify EV-A71 and EV-D68 in CSF, requiring throat or rectal samples. There is not specific treatment to these conditions and the efficacy and understanding of the mechanism of action of immune-modulatory treatment (IVIG, corticosteroids, and plasmapheresis) is limited.

Paradigmatic De Novo GRIN1 Variants Recapitulate Pathophysiological Mechanisms Underlying GRIN1-Related Disorder Clinical Spectrum.

BACKGROUND: GRIN-related disorders (GRD), the so-called grinpathies, is a group of rare encephalopathies caused by mutations affecting GRIN genes (mostly GRIN1, GRIN2A and GRIN2B genes), which encode for the GluN subunit of the N-methyl D-aspartate (NMDA) type ionotropic glutamate receptors. A growing number of functional studies indicate that GRIN-encoded GluN1 subunit disturbances can be dichotomically classified into gain- and loss-of-function, although intermediate complex scenarios are often present. METHODS: In this study, we aimed to delineate the structural and functional alterations of GRIN1 disease-associated variants, and their correlations with clinical symptoms in a Spanish cohort of 15 paediatric encephalopathy patients harbouring these variants. RESULTS: Patients harbouring GRIN1 disease-associated variants have been clinically deeply-phenotyped. Further, using computational and in vitro approaches, we identified different critical checkpoints affecting GluN1 biogenesis (protein stability, subunit assembly and surface trafficking) and/or NMDAR biophysical properties, and their association with GRD clinical symptoms. CONCLUSIONS: Our findings show a strong correlation between GRIN1 variants-associated structural and functional outcomes. This structural-functional stratification provides relevant insights of genotype-phenotype association, contributing to future precision medicine of GRIN1-related encephalopathies.

[Prevalence of autism spectrum disorders in USA, Europe and Spain: coincidences and discrepancies]. / Prevalencia de los trastornos del espectro autista en niños en Estados Unidos, Europa y España: coincidencias y discrepancias.

Autism spectrum disorders are a heterogeneous group of disorders that share the presence of two core symptoms: problems in social interaction / communication and the tendency to present restricted interests and repetitive behavior. Over the last years, several epidemiologic studies have been published by different authors in diverse countries, having all of them shown two common characteristics: a global increase in the prevalence rates of autism spectrum disorders, and the existence of a great geographical variability no only between geographical areas, but also within the same geographical areas. At the present manuscript, we analyze some of the most recent prevalence data published in USA and some European countries (including Spain). All of them show different prevalence rates, ranging from 1/59 children with autism spectrum disorders in the USA to 1/806 in Portugal. In a second part, we briefly describe some of the current scientific hypotheses that try to explain this variability.

Los trastornos del espectro autista (TEA) engloban a un grupo heterogéneo de trastornos del neurodesarrollo que tienen en común la presencia de problemas para la interacción/comunicación social y la tendencia a mostrar intereses restringidos o conductas repetitivas. Diversos estudios epidemiológicos realizados en diferentes países en los últimos años han mostrado de forma consistente dos características: el incremento progresivo en la prevalencia de los TEA a nivel mundial y la existencia de una gran variabilidad geográfica entre territorios y dentro de un mismo territorio. En el presente artículo analizamos los datos de prevalencia más recientemente publicados en EE.UU. y en diversos países de Europa (incluyendo España), que muestran tasas de prevalencia muy variables, con un rango que abarca desde 1/59 niños con trastornos del espectro autista en EE. UU., hasta 1/806 en Portugal. En un segundo tiempo describimos brevemente algunas de las principales hipótesis que intentan explicar esta variabilidad.

[Para-infectious seizures: A retrospective multicentre study]. / Crisis parainfecciosas: estudio retrospectivo multicéntrico.

INTRODUCTION: Para-infectious seizures are afebrile seizures that are associated with mild infections, and occur in children with no pre-existing neurological illness. They are still little known in our environment. METHODS: A multicentre retrospective study was conducted that included patients with normal psychomotor development and had presented with one or more seizures in the context of a mild afebrile infection. RESULTS: A total of 38 patients (47% male, 53% female) were included in the study over a period of three years (2012-2015). The mean age was 2.1 years. A previous history of febrile seizures was found in 7.9% of them. Mean number of seizures per patient was 2.2, with 57.9% of them being tonic-clonic seizures. The mean duration of seizures was 3.2minutes. An EEG was performed during admission in 73.7% of cases. Lumbar punctures were performed in 34.2% of cases. All were normal. Neuroimaging tests were carried out in 36.9% of cases. Brain MRI was the imaging test performed in most cases (21.1%), with no any pathological findings. The most frequent infection found was acute gastroenteritis (68%), followed by upper respiratory tract infection (32%). Almost two-thirds (63.2%) of patients did not require anticonvulsant medication. Rectal diazepam was the most frequently used drug in emergencies. Intravenous medication was required by 28.9% of patients due to repeated seizures. The most frequently used drug in the non-emergency setting was valproic acid. Anticonvulsant treatment was continued after discharge in 16% of patients. Para-infectious seizures was the diagnosis in 76.3% of cases when discharged. CONCLUSIONS: Knowledge of para-infectious seizures, their clinical diagnosis and benign course is crucial, as this would avoid further testing and unnecessary treatments.

Prevalencia de los trastornos del espectro autista en niños en Estados Unidos, Europa y España: coincidencias y discrepancias / Prevalence of autism spectrum disorders in USA, Europe and Spain: coincidences and discrepancies

Los trastornos del espectro autista (TEA) engloban a un grupo heterogéneo de trastornos del neurodesarrollo que tienen en común la presencia de problemas para la interacción/comunicación social y la tendencia a mostrar intereses restringidos o conductas repetitivas. Diversos estudios epidemiológicos realizados en diferentes países en los últimos años han mostrado de forma consistente dos características: el incremento progresivo en la prevalencia de los TEA a nivel mundial y la existencia de una gran variabilidad geográfica entre territorios y dentro de un mismo territorio. En el presente artículo analizamos los datos de prevalencia más recientemente publicados en EE.UU. y en diversos países de Europa (incluyendo España), que muestran tasas de prevalencia muy variables, con un rango que abarca desde 1/59 niños con trastornos del espectro autista en EE. UU., hasta 1/806 en Portugal. En un segundo tiempo describimos brevemente algunas de las principales hipótesis que intentan explicar esta variabilidad.

Autism spectrum disorders are a heterogeneous group of disorders that share the presence of two core symptoms: problems in social interaction / communication and the tendency to present restricted interests and repetitive behavior. Over the last years, several epidemiologic studies have been published by different authors in diverse countries, having all of them shown two common characteristics: a global increase in the prevalence rates of autism spectrum disorders, and the existence of a great geographical variability no only between geographical areas, but also within the same geographical areas. At the present manuscript, we analyze some of the most recent prevalence data published in USA and some European countries (including Spain). All of them show different prevalence rates, ranging from 1/59 children with autism spectrum disorders in the USA to 1/806 in Portugal. In a second part, we briefly describe some of the current scientific hypotheses that try to explain this variability.