The Australian Genomics Mitochondrial Flagship: A national program delivering mitochondrial diagnoses.

Purpose: Families living with mitochondrial diseases (MD) often endure prolonged diagnostic journeys and invasive testing, yet many remain without a molecular diagnosis. The Australian Genomics Mitochondrial Flagship, comprising clinicians, diagnostic, and research scientists, conducted a prospective national study to identify the diagnostic utility of singleton genomic sequencing using blood samples.

Methods: A total of 140 children and adults living with suspected MD were recruited using modified Nijmegen criteria (MNC) and randomized to either exome + mitochondrial DNA (mtDNA) sequencing or genome sequencing.

Diagnostic utility of exome sequencing followed by research reanalysis in human brain malformations.

This study aimed to determine the diagnostic yield of singleton exome sequencing and subsequent research-based trio exome analysis in children with a spectrum of brain malformations seen commonly in clinical practice. We recruited children ≤ 18 years old with a brain malformation diagnosed by magnetic resonance imaging and consistent with an established list of known genetic causes. Patients were ascertained nationally from eight tertiary paediatric centres as part of the Australian Genomics Brain Malformation Flagship.

Lysosomal alterations and decreased electrophysiological activity in CLN3 disease patient-derived cortical neurons.

CLN3 disease is a lysosomal storage disorder associated with fatal neurodegeneration that is caused by mutations in CLN3, with most affected individuals carrying at least one allele with a 966 bp deletion. Using CRISPR/Cas9, we corrected the 966 bp deletion mutation in human induced pluripotent stem cells (iPSCs) of a compound heterozygous patient (CLN3 Δ 966 bp and E295K). We differentiated these isogenic iPSCs, and iPSCs from an unrelated healthy control donor, to neurons and identified disease-related changes relating to protein synthesis, trafficking and degradation, and in neuronal activity, which were not apparent in CLN3-corrected or healthy control neurons.

Functional correlates of clinical phenotype and severity in recurrent SCN2A variants.

In SCN2A-related disorders, there is an urgent demand to establish efficient methods for determining the gain- (GoF) or loss-of-function (LoF) character of variants, to identify suitable candidates for precision therapies. Here we classify clinical phenotypes of 179 individuals with 38 recurrent SCN2A variants as early-infantile or later-onset epilepsy, or intellectual disability/autism spectrum disorder (ID/ASD) and assess the functional impact of 13 variants using dynamic action potential clamp (DAPC) and voltage clamp. Results show that 36/38 variants are associated with only one phenotypic group (30 early-infantile, 5 later-onset, 1 ID/ASD).

Novel Missense Mutations Associated with Infantile-Onset Developmental and Epileptic Encephalopathy.

The gene encodes the low-voltage-activated Ca3.1 channel, which is expressed in various areas of the CNS, including the cerebellum. We studied two missense variants, p.

Splice variant in ARX leading to loss of C-terminal region in a boy with intellectual disability and infantile onset developmental and epileptic encephalopathy.

Pathogenic variants in the X-chromosome Aristaless-related homeobox (ARX) gene contribute to intellectual disability, epilepsy, and associated comorbidities in affected males. Here, we report a novel splice variant in ARX in a family with three affected individuals. The proband had early onset developmental and epileptic encephalopathy, his brother and mother had severe and mild intellectual disability, respectively.

encephalopathy: A distinctive generalized developmental and epileptic encephalopathy.

Objective: To delineate the epileptology, a key part of the phenotypic spectrum, in a large patient cohort.

Methods: Patients were recruited via investigators' practices or social media. We included patients with (likely) pathogenic variants or chromosome 6p21.

Australian Clinical Consensus Guideline: The diagnosis and acute management of childhood stroke.

Stroke is among the top 10 causes of death in children and survivors carry resulting disabilities for decades, at substantial cost to themselves and their families. Children are not currently able to access reperfusion therapies, due to limited evidence supporting safety and efficacy and long diagnostic delays. The Australian Clinical Consensus Guideline for the Diagnosis and Acute Management of Childhood Stroke was developed to minimize unwarranted variations in care and document best evidence on the risk factors, etiologies, and conditions mimicking stroke that differ from adults.

Neurophysiological profile of peripheral neuropathy associated with childhood mitochondrial disease.

Introduction: Peripheral nerve involvement is common in mitochondrial disease but often unrecognised due to the prominent central nervous system features. Identification of the underlying neuropathy may assist syndrome classification, targeted genetic testing and rehabilitative interventions.

Methods: Clinical data and the results of nerve conduction studies were obtained retrospectively from the records of four tertiary children's hospital metabolic disease, neuromuscular or neurophysiology services.

Typical and atypical phenotypes of PNPO deficiency with elevated CSF and plasma pyridoxamine on treatment.

Pyridox(am)ine phosphate oxidase (PNPO) deficiency causes severe early infantile epileptic encephalopathy and has been characterized as responding to pyridoxal-5'-phosphate but not to pyridoxine. Two males with PNPO deficiency and novel PNPO mutations are reported and their clinical, metabolic, and video-electroencephalographic (EEG) findings described. The first child showed electro-clinical responses to pyridoxine and deterioration when pyridoxine was withheld.

High resolution chromosomal microarray in undiagnosed neurological disorders.

Aim: Despite advances in medical investigation, many children with neurological conditions remain without a diagnosis, although a genetic aetiology is often suspected. Chromosomal microarray (CMA) screens for copy number variants (CNVs) and long continuous stretches of homozygosity (LCSH) and may further enhance diagnostic yield. Although recent studies have identified pathogenic CNVs in intellectual disability, autism and epilepsy, the utility of CMA testing in a broader cohort of children with neurologic disorders has not been reported.

Childhood chronic inflammatory demyelinating polyneuropathy: an overview of 10 cases in the modern era.

Chronic inflammatory demyelinating polyneuropathy is a rare condition in children. In this article, we report our experience in the management of 10 cases of childhood chronic inflammatory demyelinating polyneuropathy in a single center, in the era of contrast-enhanced magnetic resonance imaging (MRI), genetic microarray, and chronic inflammatory demyelinating polyneuropathy disease activity status. Robust neurophysiologic abnormalities were present in all cases and both MRI and lumbar puncture were useful adjuncts in diagnosis.

Epileptic spasms: experience with a high-dose oral corticosteroid protocol.

Aim: To audit clinical practice and assess early outcomes for infants with epileptic spasms after an agreed initial treatment protocol was adopted.

Methods: We reviewed all cases of epileptic spasms diagnosed between July 2007 and June 2009 and assessed adherence to protocol, remission by day 14, spasm recurrence and side effects. The protocol required that infants be treated with high-dose oral prednisolone except those with tuberous sclerosis complex (TSC) who were treated with vigabatrin.

Juvenile Parkinsonism.

We present the case of a 14-year-old boy presented with a recent history of progressive neurologic decline and extrapyramidal features. The history and findings with illustrative figures are detailed, and a diagnostic approach to the presentation is considered. The therapeutic options and broader management issues are briefly reviewed.

Autoimmune myasthenia gravis, immunotherapy and thymectomy in children.

Autoimmune myasthenia gravis is a rare condition in children. Identifying antibodies directed against the acetylcholine receptor is helpful in making the diagnosis. However, seronegative cases do exist and need to be distinguished from congenital forms of myasthenia.