Publications by authors named "Tchan M"

Rare defects in the promoter region of SLC16A1, the gene encoding monocarboxylate transporter 1 (MCT-1), result in exercise-induced hyperinsulinism. In this disorder, inappropriate insulin secretion is triggered by anaerobic exercise with consequent hypoglycaemia. We describe the case of a 41-year-old man presenting with a generalised tonic-clonic seizure and severe hypoglycaemia following strenuous exercise.

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Clinically-relevant variants in the STUB1 gene have been associated with an autosomal dominant spinocerebellar ataxia 48 (SCA48), a recently described inherited neurodegenerative condition that is characterised by cognitive and psychiatric changes. To describe the clinical phenotype and genetic findings of three new Australian probands with STUB1 to expand the current understanding of the spectrum of clinical presentation and natural history of SCA48. Clinical and genetic review of patients diagnosed with SCA48 ataxia drawn from our centres.

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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.

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Article Synopsis
  • Diagnostic genomic sequencing is becoming essential in nephrology, with efforts to enhance its national implementation to benefit patient outcomes.
  • A national study established 20 kidney genetics clinics across Australia from 2013 to 2022, offering genomic testing for patients with suspected monogenic kidney diseases and facilitating the collection of data on diagnostic experiences.
  • The initiative successfully integrated a multidisciplinary approach to kidney genetics, optimizing care for patients while adapting to ongoing technological advancements and preparing for broader healthcare funding for genomic testing.
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The KidGen Collaborative's Policy Implementation Workshop 2023 celebrated the 10th anniversary of Australia's first kidney genetics clinic in Brisbane. This event marked the establishment of a national network now comprising 19 kidney genetics clinics across Australia, all dedicated to providing equitable access to genomic testing for families affected by genetic kidney diseases. The workshop reflected on past progress and outlined future objectives for kidney genetics in Australia, recognising the collaborative efforts of clinical teams, researchers, and patients.

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Article Synopsis
  • About 25% of patients with unexplained kidney failure have a genetic cause, specifically related to monogenic disorders.
  • A study explored the effectiveness of whole genome sequencing (WGS) combined with broad gene panel analysis in diagnosing these cases, finding it to be a viable method for identifying genetic mutations.
  • Among 100 participants aged ≤50 with stage 5 chronic kidney disease, a genetic diagnosis was reached in 25%, with a higher likelihood of positive results in those with a family history of chronic kidney disease.
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  • This study aimed to assess how reanalyzing genomic data can help identify diagnoses in dystonia patients who previously had inconclusive results.
  • Initially, only 11.7% of 111 patients received a molecular diagnosis from the first genome sequencing in 2019, but reanalysis between 2020 and 2023 increased that rate to 18.9%.
  • The findings suggest that regularly revisiting genomic data can lead to more genetic diagnoses, which can be crucial for better understanding and managing the condition for patients and their families.
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Background: Variants in dehydrodolichol diphosphate synthetase (DHDDS) and nuclear undecaprenyl pyrophosphate synthase 1 (NUS1) cause a neurodevelopmental disorder, classically with prominent epilepsy. Recent reports suggest a complex movement disorder and an overlapping phenotype has been postulated due to their combined role in dolichol synthesis.

Cases: We describe three patients with heterozygous variants in DHDDS and five with variants affecting NUS1.

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Background: Disease-specific therapy aims to improve symptoms, stabilise current disease and delay progression in patients with Fabry disease. In Australia, treatment access is subject to eligibility criteria initially established in 2004. Patients and their clinicians question why these criteria have remained unchanged despite significant progress in disease understanding.

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An increasing number of women with urea cycle disorders (UCDs) are reaching child-bearing age and becoming pregnant. Improved diagnostics and increased awareness of inherited metabolic diseases has also led to more previously undetected women being diagnosed with a UCD during or shortly after pregnancy. Pregnancy increases the risk of acute metabolic decompensation with hyperammonemia-which can occur in any trimester, and/or the postpartum period, and may lead to encephalopathy, psychosis, coma, and even death, if not diagnosed promptly and treated appropriately.

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Background: Olipudase alfa is a recombinant human acid sphingomyelinase enzyme replacement therapy for non-central-nervous-system manifestations of acid sphingomyelinase deficiency (ASMD). The ASCEND randomized placebo-controlled trial in adults with ASMD demonstrated reductions in sphingomyelin storage, organomegaly, interstitial lung disease and impaired diffusion capacity of the lung (DL), during the first year of olipudase alfa treatment. In an ongoing open-label extension of the ASCEND trial, individuals in the placebo group crossed over to olipudase alfa, and those in the olipudase alfa group continued treatment.

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A 19-year-old woman with known maple syrup urine disease presented to hospital with metabolic crisis in the setting of influenza type A infection and intractable vomiting, rapidly progressing to acute cerebral oedema manifesting as refractory seizures and decreased level of consciousness needing emergency intubation and mechanical ventilation, continuous veno-venous haemodiafiltration and thiopentone coma. A computed tomography scan and magnetic resonance imaging of the brain demonstrated classic signs of cerebral oedema secondary to a metabolic crisis from the metabolic disorder. Her management posed multiple challenges to all teams involved due to lack of familiarity and experience in managing this clinical scenario in the adult intensive care setting.

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We report ATP1A3-associated rapid-onset dystonia-parkinsonism with an atypical presentation including myoclonus and exaggerated startle in four patients. Their prominence over parkinsonism prompted consideration of a syndromic diagnosis of myoclonus dystonia. ATP1α3 dysfunction in GABAergic neurons could explain these examination findings.

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Background: Advances in genomics provide improved opportunities for diagnosis of complex neurogenetic disorders, yet the optimal approach to translate these benefits to the outpatient clinic is unclear.

Aims: We retrospectively reviewed referral indications and outcomes of an integrated multidisciplinary team (MDT) clinic pathway for adults with suspected neurogenetic disorders. The associated cost implications were estimated.

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3-Hydroxy-3-Methylglutaryl-CoA Lyase (HMGCL) deficiency can be a very severe disorder that typically presents with acute metabolic decompensation with features of hypoketotic hypoglycemia, hyperammonemia, and metabolic acidosis. A retrospective chart and literature review of Australian patients over their lifespan, incorporating acute and long-term dietary management, was performed. Data from 10 patients contributed to this study.

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Background And Objectives: The term autosomal recessive cerebellar ataxia (ARCA) encompasses a diverse group of heterogeneous degenerative disorders of the cerebellum. Spinocerebellar ataxia autosomal recessive 10 (SCAR10) is a distinct classification of cerebellar ataxia caused by variants in the gene. Little is known about the molecular role of ANO10 or its role in disease.

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Non-coding regions are areas of the genome that do not directly encode protein and were initially thought to be of little biological relevance. However, subsequent identification of pathogenic variants in these regions indicates there are exceptions to this assertion. With the increasing availability of next generation sequencing, variants in non-coding regions are often considered when no causative exonic changes have been identified.

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Article Synopsis
  • * A case study describes a patient with premature ovarian insufficiency (POI), sensorineural hearing loss, and Hashimoto's disease, suggesting a link to Perrault syndrome.
  • * Whole exome sequencing identified two novel pathogenic variants in a gene associated with the condition, supporting the connection between mitochondrial ribosome function and ovarian health.
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The mutation c.-32-13T>G in the GAA gene impacts normal exon 2 splicing and is found in two-thirds of late-onset Pompe disease cases. We have explored a therapeutic strategy using splice modulating phosphorodiamidate morpholino oligomers to enhance GAA exon 2 inclusion in the mature mRNA of patients carrying this common mutation.

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Purpose: This paper aims to report collective information on safety and efficacy of empagliflozin drug repurposing in individuals with glycogen storage disease type Ib (GSD Ib).

Methods: This is an international retrospective questionnaire study on the safety and efficacy of empagliflozin use for management of neutropenia/neutrophil dysfunction in patients with GSD Ib, conducted among the respective health care providers from 24 countries across the globe.

Results: Clinical data from 112 individuals with GSD Ib were evaluated, representing a total of 94 treatment years.

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