Untargeted metabolomics analysis as a potential screening tool for 3-methylglutaconic aciduria syndromes.

The 3-methylglutaconic aciduria (3-MGA-uria) syndromes comprise a heterogeneous group of inborn errors of metabolism defined biochemically by detectable elevation of 3-methylglutaconic acid (3-MGA) in the urine. In type 1 (or primary) 3-MGA-uria, distal defects in the leucine catabolism pathway directly cause this elevation. Secondary 3-MGA-uria syndromes, however, are unrelated to leucine metabolism-specific defects but share a common biochemical phenotype of elevated 3-MGA.

Neurodevelopmental Disorder Caused by Deletion of , a lncRNA Gene.

encodes a human long noncoding RNA (lncRNA) adjacent to , a coding gene in which de novo loss-of-function variants cause developmental and epileptic encephalopathy. Here, we report our findings in three unrelated children with a syndromic, early-onset neurodevelopmental disorder, each of whom had a de novo deletion in the locus. The children had severe encephalopathy, shared facial dysmorphisms, cortical atrophy, and cerebral hypomyelination - a phenotype that is distinct from the phenotypes of patients with haploinsufficiency.

Recessive loss-of-function variants in DPH1 identified as the molecular cause in a sibling pair previously diagnosed with Fine-Lubinsky syndrome.

Fine-Lubinsky syndrome is a rare clinically defined syndrome sometimes referred to as brachycephaly, deafness, cataract, microstomia, and impaired intellectual development syndrome. Here we provide a clinical and molecular update for a sibling pair diagnosed with Fine-Lubinsky syndrome. An extensive genetic work-up, including chromosomal microarray analysis and quad exome sequencing, was nondiagnostic.

Developmental delay can precede neurologic regression in early onset metachromatic leukodystrophy.

Objective: Metachromatic leukodystrophy (MLD) is a rare neurodegenerative disorder. Emerging therapies are most effective in the presymptomatic phase, and thus defining this window is critical. We hypothesize that early development delay may precede developmental plateau.

Disease Spectrum Includes Paroxysmal Weakness and Encephalopathy Not Triggered by Fever.

Background And Objectives: Heterozygous pathogenic variants in , which encodes the catalytic alpha subunit of neuronal Na/K-ATPase, cause primarily neurologic disorders with widely variable features that can include episodic movement deficits. One distinctive presentation of -related disease is recurrent fever-triggered encephalopathy. This can occur with generalized weakness and/or ataxia and is described in the literature as relapsing encephalopathy with cerebellar ataxia.

Consensus guidelines for the monitoring and management of metachromatic leukodystrophy in the United States.

Metachromatic leukodystrophy (MLD) is a fatal, progressive neurodegenerative disorder caused by biallelic pathogenic mutations in the ARSA (Arylsulfatase A) gene. With the advent of presymptomatic diagnosis and the availability of therapies with a narrow window for intervention, it is critical to define a standardized approach to diagnosis, presymptomatic monitoring, and clinical care. To meet the needs of the MLD community, a panel of MLD experts was established to develop disease-specific guidelines based on healthcare resources in the United States.

The clinical utility and diagnostic implementation of human subject cell transdifferentiation followed by RNA sequencing.

RNA sequencing (RNA-seq) has recently been used in translational research settings to facilitate diagnoses of Mendelian disorders. A significant obstacle for clinical laboratories in adopting RNA-seq is the low or absent expression of a significant number of disease-associated genes/transcripts in clinically accessible samples. As this is especially problematic in neurological diseases, we developed a clinical diagnostic approach that enhanced the detection and evaluation of tissue-specific genes/transcripts through fibroblast-to-neuron cell transdifferentiation.

Longitudinal natural history studies based on real-world data in rare diseases: Opportunity and a novel approach.

Growing interest in therapeutic development for rare diseases necessitate a systematic approach to the collection and curation of natural history data that can be applied consistently across this group of heterogenous rare diseases. In this study, we discuss the challenges facing natural history studies for leukodystrophies and detail a novel standardized approach to creating a longitudinal natural history study using existing medical records. Prospective studies are uniquely challenging for rare diseases.

Heterozygous MAP3K20 variants cause ectodermal dysplasia, craniosynostosis, sensorineural hearing loss, and limb anomalies.

Biallelic pathogenic variants in MAP3K20, which encodes a mitogen-activated protein kinase, are a rare cause of split-hand foot malformation (SHFM), hearing loss, and nail abnormalities or congenital myopathy. However, heterozygous variants in this gene have not been definitively associated with a phenotype. Here, we describe the phenotypic spectrum associated with heterozygous de novo variants in the linker region between the kinase domain and leucine zipper domain of MAP3K20.

Expanded clinical phenotype and untargeted metabolomics analysis in RARS2-related mitochondrial disorder: a case report.

Background: RARS2-related mitochondrial disorder is an autosomal recessive mitochondrial encephalopathy caused by biallelic pathogenic variants in the gene encoding the mitochondrial arginyl-transfer RNA synthetase 2 (RARS2, MIM *611524, NM_020320.5). RARS2 catalyzes the transfer of L-arginine to its cognate tRNA during the translation of mitochondrially-encoded proteins.

Functional genomics and small molecules in mitochondrial neurodevelopmental disorders.

Mitochondria are critical for brain development and homeostasis. Therefore, pathogenic variation in the mitochondrial or nuclear genome which disrupts mitochondrial function frequently results in developmental disorders and neurodegeneration at the organismal level. Large-scale application of genome-wide technologies to individuals with mitochondrial diseases has dramatically accelerated identification of mitochondrial disease-gene associations in humans.

Biallelic variants in SLC4A10 encoding a sodium-dependent bicarbonate transporter lead to a neurodevelopmental disorder.

Purpose: SLC4A10 encodes a plasma membrane-bound transporter, which mediates Na-dependent HCO import, thus mediating net acid extrusion. Slc4a10 knockout mice show collapsed brain ventricles, an increased seizure threshold, mild behavioral abnormalities, impaired vision, and deafness.

Methods: Utilizing exome/genome sequencing in families with undiagnosed neurodevelopmental disorders and international data sharing, 11 patients from 6 independent families with biallelic variants in SLC4A10 were identified.

Gain-of-function and loss-of-function variants in GRIA3 lead to distinct neurodevelopmental phenotypes.

AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors (AMPARs) mediate fast excitatory neurotransmission in the brain. AMPARs form by homo- or heteromeric assembly of subunits encoded by the GRIA1-GRIA4 genes, of which only GRIA3 is X-chromosomal. Increasing numbers of GRIA3 missense variants are reported in patients with neurodevelopmental disorders (NDD), but only a few have been examined functionally.

De novo missense variants in ZBTB47 are associated with developmental delays, hypotonia, seizures, gait abnormalities, and variable movement abnormalities.

The collection of known genetic etiologies of neurodevelopmental disorders continues to increase, including several syndromes associated with defects in zinc finger protein transcription factors (ZNFs) that vary in clinical severity from mild learning disabilities and developmental delay to refractory seizures and severe autism spectrum disorder. Here we describe a new neurodevelopmental disorder associated with variants in ZBTB47 (also known as ZNF651), which encodes zinc finger and BTB domain-containing protein 47. Exome sequencing (ES) was performed for five unrelated patients with neurodevelopmental disorders.

Fetal Neurology Practice Survey: Current Practice and the Future Directions.

Background: Fetal neurology is a rapidly evolving field. Consultations aim to diagnose, prognosticate, and coordinate prenatal and perinatal management along with other specialists and counsel expectant parents. Practice parameters and guidelines are limited.

Bi-allelic SNAPC4 variants dysregulate global alternative splicing and lead to neuroregression and progressive spastic paraparesis.

The vast majority of human genes encode multiple isoforms through alternative splicing, and the temporal and spatial regulation of those isoforms is critical for organismal development and function. The spliceosome, which regulates and executes splicing reactions, is primarily composed of small nuclear ribonucleoproteins (snRNPs) that consist of small nuclear RNAs (snRNAs) and protein subunits. snRNA gene transcription is initiated by the snRNA-activating protein complex (SNAPc).

Natural history of posterior fetal cephaloceles and incidence of progressive cephalocele herniation.

Objective: In utero repair of fetal posterior cephaloceles (meningocele and encephalocele) is being performed based on the premise that fetal surgery prevents progressive herniation of neural tissue and brain damage during pregnancy. However, the extent to which progressive herniation occurs during pregnancy, specifically from prenatal diagnosis to after delivery, is not well known. The objective of this study was to describe the natural history of patients with fetal cephaloceles focusing on the incidence of progressive herniation.

KCNQ2 R144 variants cause neurodevelopmental disability with language impairment and autistic features without neonatal seizures through a gain-of-function mechanism.

Background: Prior studies have revealed remarkable phenotypic heterogeneity in KCNQ2-related disorders, correlated with effects on biophysical features of heterologously expressed channels. Here, we assessed phenotypes and functional properties associated with KCNQ2 missense variants R144W, R144Q, and R144G. We also explored in vitro blockade of channels carrying R144Q mutant subunits by amitriptyline.

Biallelic Variants in the Ectonucleotidase ENTPD1 Cause a Complex Neurodevelopmental Disorder with Intellectual Disability, Distinct White Matter Abnormalities, and Spastic Paraplegia.

Objective: Human genomics established that pathogenic variation in diverse genes can underlie a single disorder. For example, hereditary spastic paraplegia is associated with >80 genes, with frequently only few affected individuals described for each gene. Herein, we characterize a large cohort of individuals with biallelic variation in ENTPD1, a gene previously linked to spastic paraplegia 64 (Mendelian Inheritance in Man # 615683).

A novel, de novo intronic variant in POGZ causes White-Sutton syndrome.

White-Sutton syndrome (WHSUS), which is caused by heterozygous pathogenic variants in POGZ, is characterized by a spectrum of intellectual disabilities and global developmental delay with or without features of autism spectrum disorder. Additional features may include hypotonia, behavioral abnormalities, ophthalmic abnormalities, hearing loss, sleep apnea, microcephaly, dysmorphic facial features, and rarely, congenital diaphragmatic hernia (CDH). We present a 6-year-old female with features of WHSUS, including CDH, but with nondiagnostic clinical trio exome sequencing.