1
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Cunningham SC, van Dijk EB, Zhu E, Sugden M, Mandwie M, Siew S, Devanapalli B, Tolun AA, Klein A, Wilson L, Aryamanesh N, Gissen P, Baruteau J, Bhattacharya K, Alexander IE. Recapitulation of Skewed X-Inactivation in Female Ornithine Transcarbamylase-Deficient Primary Human Hepatocytes in the FRG Mouse: A Novel System for Developing Epigenetic Therapies. Hum Gene Ther 2023; 34:917-926. [PMID: 37350098 DOI: 10.1089/hum.2023.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2023] Open
Abstract
Realization of the immense therapeutic potential of epigenetic editing requires development of clinically predictive model systems that faithfully recapitulate relevant aspects of the target disease pathophysiology. In female patients with ornithine transcarbamylase (OTC) deficiency, an X-linked condition, skewed inactivation of the X chromosome carrying the wild-type OTC allele is associated with increased disease severity. The majority of affected female patients can be managed medically, but a proportion require liver transplantation. With rapid development of epigenetic editing technology, reactivation of silenced wild-type OTC alleles is becoming an increasingly plausible therapeutic approach. Toward this end, privileged access to explanted diseased livers from two affected female infants provided the opportunity to explore whether engraftment and expansion of dissociated patient-derived hepatocytes in the FRG mouse might produce a relevant model for evaluation of epigenetic interventions. Hepatocytes from both infants were successfully used to generate chimeric mouse-human livers, in which clusters of primary human hepatocytes were either OTC positive or negative by immunohistochemistry (IHC), consistent with clonal expansion from individual hepatocytes in which the mutant or wild-type OTC allele was inactivated, respectively. Enumeration of the proportion of OTC-positive or -negative human hepatocyte clusters was consistent with dramatic skewing in one infant and minimal to modest skewing in the other. Importantly, IHC and fluorescence-activated cell sorting analysis of intact and dissociated liver samples from both infants showed qualitatively similar patterns, confirming that the chimeric mouse-human liver model recapitulated the native state in each infant. Also of importance was the induction of a treatable metabolic phenotype, orotic aciduria, in mice, which correlated with the presence of clonally expanded OTC-negative primary human hepatocytes. We are currently using this unique model to explore CRISPR-dCas9-based epigenetic targeting strategies in combination with efficient adeno-associated virus (AAV) gene delivery to reactivate the silenced functional OTC gene on the inactive X chromosome.
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Affiliation(s)
- Sharon C Cunningham
- Gene Therapy Research Unit, Faculty of Medicine and Health, Children's Medical Research Institute, The University of Sydney and Sydney Children's Hospitals Network, Westmead, Australia
| | - Eva B van Dijk
- Gene Therapy Research Unit, Faculty of Medicine and Health, Children's Medical Research Institute, The University of Sydney and Sydney Children's Hospitals Network, Westmead, Australia
| | - Erhua Zhu
- Gene Therapy Research Unit, Faculty of Medicine and Health, Children's Medical Research Institute, The University of Sydney and Sydney Children's Hospitals Network, Westmead, Australia
| | - Maya Sugden
- Gene Therapy Research Unit, Faculty of Medicine and Health, Children's Medical Research Institute, The University of Sydney and Sydney Children's Hospitals Network, Westmead, Australia
| | - Mawj Mandwie
- Gene Therapy Research Unit, Faculty of Medicine and Health, Children's Medical Research Institute, The University of Sydney and Sydney Children's Hospitals Network, Westmead, Australia
| | - Susan Siew
- Department of Gastroenterology, James Fairfax Institute of Paediatric Nutrition, Sydney Children's Hospitals Network, Westmead, Australia
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, Australia
| | - Beena Devanapalli
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, Australia
| | - Adviye Ayper Tolun
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, Australia
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, Australia
| | - Anne Klein
- Australian e-Health Research Centre, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Sydney, Australia
| | - Laurence Wilson
- Australian e-Health Research Centre, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Sydney, Australia
- Department of Biomedical Sciences, Macquarie University, Macquarie Park, Australia
| | - Nader Aryamanesh
- Embryology Research Unit, Bioinformatics Group, Children's Medical Research Institute, University of Sydney, Westmead, Australia
| | - Paul Gissen
- National Institute for Health Research Great Ormond Street Hospital Biomedical Research Centre, University College London, London, United Kingdom
| | - Julien Baruteau
- National Institute for Health Research Great Ormond Street Hospital Biomedical Research Centre, University College London, London, United Kingdom
| | - Kaustuv Bhattacharya
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, Australia
- Genetic Metabolic Disorders Service, The Children's Hospital at Westmead, Sydney, Australia
| | - Ian E Alexander
- Gene Therapy Research Unit, Faculty of Medicine and Health, Children's Medical Research Institute, The University of Sydney and Sydney Children's Hospitals Network, Westmead, Australia
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, Australia
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2
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Evesson FJ, Dziaduch G, Bryen SJ, Moore F, Pittman S, Devanapalli B, Waddell LB, Ryan MM, Menezes M, Weihl CC, Tolun AA, Zaidman C, Young H, Adès LC, Cooper ST. PYROXD1 variants cause an overlapping myopathy and connective tissue disorder. Hum Mol Genet 2023:7078393. [PMID: 36920481 DOI: 10.1093/hmg/ddad035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 02/16/2023] [Indexed: 03/16/2023] Open
Abstract
Recessive variants in the oxidoreductase PYROXD1 are reported to cause a myopathy in 22 affected individuals from 15 families. Here we describe two female probands from unrelated families presenting with features of a congenital connective tissue disorder including osteopenia, blue sclera, soft skin, joint hypermobility and neuromuscular junction dysfunction in addition to known features of PYROXD1 myopathy including respiratory difficulties, weakness, hypotonia and oromotor dysfunction. Proband AII:1 is compound heterozygous for the recurrent PYROXD1 variant Chr12 (GRCh38):g.21452130A > G;NM_024854.5:c.464A > G;p.(N155S) and Chr12(GRCh38):g.21462019_21462022del;NM_024854.5:c.892_895del;p.(V298Mfs*4) and proband BII:1 is compound heterozygous for Chr12(GRCh38):g.21468739-21468741del;NM_024854.5:c.1488_1490del;p.(E496del) and Chr12(GRCh38):g21467619del; NM_024854.5:c.1254 + 1del. RNA studies demonstrate c.892_895del;p.(V298Mfs*4) is targeted by nonsense mediated decay and c.1254 + 1delG elicits in-frame skipping of exon-11. Western blot from cultured fibroblasts shows reduced PYROXD1 protein levels in both probands. Testing urine from BII:1 and six individuals with PYROXD1 myopathy showed elevated levels of deoxypyridinoline (DPD), a mature collagen crosslink, correlating with PYROXD1-disorder severity. Urine and serum amino acid testing of the same individuals revealed no reportable changes. In contrast to PYROXD1 knock-out, we find no evidence for disrupted tRNA ligase activity, as measured via XBP1 splicing, in fibroblasts expressing PYROXD1 variants. In summary, we expand the clinical spectrum of PYROXD1-related disorders to include an overlapping connective tissue and myopathy presentation, identify three novel, pathogenic PYROXD1 variants, and provide preliminary evidence that elevated urine DPD crosslinks may provide a clinical biomarker for PYROXD1 disorders. Our results advocate consideration of PYROXD1 variants in the differential diagnosis for undiagnosed individuals presenting with a connective tissue disorder and myopathy.
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Affiliation(s)
- Frances J Evesson
- Kids Neuroscience Centre, Kids Research Institute, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Functional Neuromics, Children's Medical Research Institute, The University of Sydney, Westmead NSW, Australia
| | - Gregory Dziaduch
- Kids Neuroscience Centre, Kids Research Institute, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Functional Neuromics, Children's Medical Research Institute, The University of Sydney, Westmead NSW, Australia
| | - Samantha J Bryen
- Kids Neuroscience Centre, Kids Research Institute, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia
| | - Francesca Moore
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Sara Pittman
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Beena Devanapalli
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Leigh B Waddell
- Kids Neuroscience Centre, Kids Research Institute, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia
| | - Monique M Ryan
- Royal Children's Hospital, Murdoch Children's Research Institute and University of Melbourne, Melbourne Australia
| | - Manoj Menezes
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia.,Department of Neurology, Children's Hospital at Westmead, Westmead, New South Wales, Australia
| | - Conrad C Weihl
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Adviye Ayper Tolun
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia.,NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Craig Zaidman
- Department of Neurology, Divisions of Child Neurology and Neuromuscle, Washington University in St. Louis School of Medicine
| | - Helen Young
- Department of Clinical Genetics, The Children's Hospital at Westmead, Sydney Australia
| | - Lesley C Adès
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia.,Department of Clinical Genetics, The Children's Hospital at Westmead, Sydney Australia
| | - Sandra T Cooper
- Kids Neuroscience Centre, Kids Research Institute, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Functional Neuromics, Children's Medical Research Institute, The University of Sydney, Westmead NSW, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia
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3
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Coupe S, Hertzog A, Foran C, Tolun AA, Suthern M, Chung CWT, Ellaway C. Keeping you on your toes: Smith-Lemli-Opitz Syndrome is an easily missed cause of developmental delays. Clin Case Rep 2023; 11:e6920. [PMID: 36814711 PMCID: PMC9939576 DOI: 10.1002/ccr3.6920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/10/2022] [Accepted: 12/28/2022] [Indexed: 02/22/2023] Open
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a relatively common genetic cause of developmental delay and may only present in conjunction with 2,3 toe syndactyly. This case series illustrates a milder phenotype of SLOS, where the predominant findings are neurocognitive in the presence of 2,3 toe syndactyly.
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Affiliation(s)
- Simone Coupe
- NSW Biochemical Genetics ServiceThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia
| | - Ashley Hertzog
- NSW Biochemical Genetics ServiceThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia,Faculty of Medicine and HealthUniversity of SydneyWestmeadNew South WalesAustralia
| | - Carolyn Foran
- NSW Biochemical Genetics ServiceThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia
| | - Adviye Ayper Tolun
- NSW Biochemical Genetics ServiceThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia,Faculty of Medicine and HealthUniversity of SydneyWestmeadNew South WalesAustralia
| | - Megan Suthern
- Paediatric DepartmentWagga Wagga Base HospitalWagga WaggaNew South WalesAustralia,Rural Clinical School, Faculty of Medicine and HealthUniversity of New South WalesWagga WaggaNew South WalesAustralia
| | - Clara W. T. Chung
- Department of Clinical GeneticsLiverpool HospitalLiverpoolNew South WalesAustralia,School of Women's and Children's HealthUniversity of New South WalesSydneyNew South WalesAustralia
| | - Carolyn Ellaway
- Faculty of Medicine and HealthUniversity of SydneyWestmeadNew South WalesAustralia,Genetic Metabolic Disorders ServiceThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia
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4
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Hertzog A, Selvanathan A, Farnsworth E, Tchan M, Adams L, Lewis K, Tolun AA, Bennetts B, Ho G, Bhattacharya K. Intronic variants in inborn errors of metabolism: Beyond the exome. Front Genet 2022; 13:1031495. [PMID: 36561316 PMCID: PMC9763607 DOI: 10.3389/fgene.2022.1031495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/15/2022] [Indexed: 12/12/2022] Open
Abstract
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. There is still a lack of understanding of normal human variation in non-coding areas. As a result, potentially pathogenic non-coding variants are initially classified as variants of uncertain significance or are even overlooked during genomic analysis. In most cases where the phenotype is non-specific, clinical suspicion is not sufficient to warrant further exploration of these changes, partly due to the magnitude of non-coding variants identified. In contrast, inborn errors of metabolism (IEMs) are one group of genetic disorders where there is often high phenotypic specificity. The clinical and biochemical features seen often result in a narrow list of diagnostic possibilities. In this context, there have been numerous cases in which suspicion of a particular IEM led to the discovery of a variant in a non-coding region. We present four patients with IEMs where the molecular aetiology was identified within non-coding regions. Confirmation of the molecular diagnosis is often aided by the clinical and biochemical specificity associated with IEMs. Whilst the clinical severity associated with a non-coding variant can be difficult to predict, obtaining a molecular diagnosis is crucial as it ends diagnostic odysseys and assists in management.
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Affiliation(s)
- Ashley Hertzog
- NSW Biochemical Genetics Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW, Australia,Disciplines of Genetic Medicine and Child and Adolescent Health, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia,*Correspondence: Ashley Hertzog,
| | - Arthavan Selvanathan
- Genetic Metabolic Disorders Service, Sydney Children’s Hospitals Network, Sydney, NSW, Australia
| | - Elizabeth Farnsworth
- Department of Molecular Genetics, Sydney Genome Diagnostics, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW, Australia
| | - Michel Tchan
- Department of Genetic Medicine, Westmead Hospital, Sydney, NSW, Australia
| | - Louisa Adams
- Genetic Metabolic Disorders Service, Sydney Children’s Hospitals Network, Sydney, NSW, Australia
| | - Katherine Lewis
- Genetic Metabolic Disorders Service, Sydney Children’s Hospitals Network, Sydney, NSW, Australia
| | - Adviye Ayper Tolun
- NSW Biochemical Genetics Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW, Australia,Disciplines of Genetic Medicine and Child and Adolescent Health, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Bruce Bennetts
- Disciplines of Genetic Medicine and Child and Adolescent Health, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia,Department of Molecular Genetics, Sydney Genome Diagnostics, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW, Australia
| | - Gladys Ho
- Disciplines of Genetic Medicine and Child and Adolescent Health, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia,Department of Molecular Genetics, Sydney Genome Diagnostics, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW, Australia
| | - Kaustuv Bhattacharya
- Disciplines of Genetic Medicine and Child and Adolescent Health, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia,Genetic Metabolic Disorders Service, Sydney Children’s Hospitals Network, Sydney, NSW, Australia
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5
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Hertzog A, Selvanathan A, Devanapalli B, Ho G, Bhattacharya K, Tolun AA. A narrative review of metabolomics in the era of "-omics": integration into clinical practice for inborn errors of metabolism. Transl Pediatr 2022; 11:1704-1716. [PMID: 36345452 PMCID: PMC9636448 DOI: 10.21037/tp-22-105] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 08/23/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Traditional targeted metabolomic investigations identify a pre-defined list of analytes in samples and have been widely used for decades in the diagnosis and monitoring of inborn errors of metabolism (IEMs). Recent technological advances have resulted in the development and maturation of untargeted metabolomics: a holistic, unbiased, analytical approach to detecting metabolic disturbances in human disease. We aim to provide a summary of untargeted metabolomics [focusing on tandem mass spectrometry (MS-MS)] and its application in the field of IEMs. METHODS Data for this review was identified through a literature search using PubMed, Google Scholar, and personal repositories of articles collected by the authors. Findings are presented within several sections describing the metabolome, the current use of targeted metabolomics in the diagnostic pathway of patients with IEMs, the more recent integration of untargeted metabolomics into clinical care, and the limitations of this newly employed analytical technique. KEY CONTENT AND FINDINGS Untargeted metabolomic investigations are increasingly utilized in screening for rare disorders, improving understanding of cellular and subcellular physiology, discovering novel biomarkers, monitoring therapy, and functionally validating genomic variants. Although the untargeted metabolomic approach has some limitations, this "next generation metabolic screening" platform is becoming increasingly affordable and accessible. CONCLUSIONS When used in conjunction with genomics and the other promising "-omic" technologies, untargeted metabolomics has the potential to revolutionize the diagnostics of IEMs (and other rare disorders), improving both clinical and health economic outcomes.
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Affiliation(s)
- Ashley Hertzog
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Arthavan Selvanathan
- Genetic Metabolic Disorders Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Beena Devanapalli
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Gladys Ho
- Sydney Genome Diagnostics, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Specialty of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Kaustuv Bhattacharya
- Genetic Metabolic Disorders Service, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Specialty of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Adviye Ayper Tolun
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Specialty of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
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6
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Hertzog A, Selvanathan A, Pandithan D, Kim W, Kava MP, Boneh A, Coman D, Tolun AA, Bhattacharya K. 3‐Methylglutaconyl‐CoA
hydratase deficiency: When ascertainment bias confounds a biochemical diagnosis. JIMD Rep 2022; 63:568-574. [DOI: 10.1002/jmd2.12332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/28/2022] [Accepted: 08/30/2022] [Indexed: 11/10/2022] Open
Affiliation(s)
- Ashley Hertzog
- NSW Biochemical Genetics Service, Western Sydney Genetics Program The Children's Hospital at Westmead Westmead New South Wales Australia
- Disciplines of Genetic Medicine and Child and Adolescent Health The University of Sydney Sydney New South Wales Australia
| | - Arthavan Selvanathan
- Genetic Metabolic Disorders Service Sydney Children's Hospital Network Sydney New South Wales Australia
- Queensland Lifespan Metabolic Medicine Service Queensland Children's Hospital Brisbane Queensland Australia
| | - Dinusha Pandithan
- Department of Metabolic Medicine The Royal Children's Hospital Parkville Victoria Australia
| | - Won‐Tae Kim
- NSW Newborn Screening Programme The Children's Hospital at Westmead Westmead New South Wales Australia
| | - Maina P. Kava
- Metabolic Unit, Department of Rheumatology and Metabolic Medicine Perth Children's Hospital Perth Western Australia Australia
- School of Paediatrics and Child Health University of Western Australia Perth Western Australia Australia
| | - Avihu Boneh
- Department of Paediatrics University of Melbourne Parkville Victoria Australia
| | - David Coman
- Queensland Lifespan Metabolic Medicine Service Queensland Children's Hospital Brisbane Queensland Australia
- School of Medicine University of Queensland Brisbane Queensland Australia
| | - Adviye Ayper Tolun
- NSW Biochemical Genetics Service, Western Sydney Genetics Program The Children's Hospital at Westmead Westmead New South Wales Australia
- Disciplines of Genetic Medicine and Child and Adolescent Health The University of Sydney Sydney New South Wales Australia
| | - Kaustuv Bhattacharya
- Disciplines of Genetic Medicine and Child and Adolescent Health The University of Sydney Sydney New South Wales Australia
- Genetic Metabolic Disorders Service Sydney Children's Hospital Network Sydney New South Wales Australia
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7
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Hertzog A, Selvanathan A, Halligan R, Fazio T, Jong G, Bratkovic D, Bhattacharya K, Tolun AA, Bennetts B, Fisk K. A serendipitous journey to a promoter variant: The c.‐
106C
>A variant and its role in late‐onset ornithine transcarbamylase deficiency. JIMD Rep 2022; 63:271-275. [PMID: 35822098 PMCID: PMC9259394 DOI: 10.1002/jmd2.12289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/15/2022] [Accepted: 04/01/2022] [Indexed: 11/19/2022] Open
Abstract
Ornithine transcarbamylase deficiency (OTCD) is an X‐linked urea cycle disorder characterised by reduced or absent OTC enzyme activity, resulting in the accumulation of neurotoxic ammonia. Approximately 80%–90% of the causative variants are identified by Sanger sequencing or multiplex ligation‐dependent probe amplification (MLPA) of the OTC gene. A 23‐year‐old male with biochemical evidence of OTCD was referred for molecular analysis. Initial Sanger sequencing yielded no pathogenic variants. MLPA testing raised suspicion of a mosaic deletion of exon 1; however, high‐resolution microarray did not identify a copy number variant on the X chromosome. Sequencing over the suspected breakpoint detected a hemizygous likely pathogenic promoter variant, c.‐106C > A, which was located within the MLPA probe binding site. Subsequently, historical patients referred to our centre, without a molecular aetiology for their OTCD, were re‐sequenced with these primers and this variant was also identified in two additional unrelated males. All three patients described in this case series have the late‐onset disease. Two presented at 5 years of age with vomiting, whilst the other was managed from birth based on a family history of late‐onset OTCD. One patient required liver transplantation due to recurrent decompensations; the other two are managed with a protein‐restricted diet. All three patients have not sustained any significant neurological insults and are functioning well as adults. These cases support screening of the promoter region within the OTC gene, particularly if a molecular basis has not been elucidated by MLPA or sequencing of the coding regions.
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Affiliation(s)
- Ashley Hertzog
- NSW Biochemical Genetics Service The Children's Hospital at Westmead Westmead New South Wales Australia
| | - Arthavan Selvanathan
- Genetic Metabolic Disorders Service The Children's Hospital at Westmead Westmead New South Wales Australia
| | - Rebecca Halligan
- Metabolic Unit Women's and Children's Hospital Adelaide South Australia Australia
| | - Timothy Fazio
- Metabolic Diseases Unit Royal Melbourne Hospital Parkville Victoria Australia
- Melbourne Medical School University of Melbourne Parkville Victoria Australia
| | - Gerard Jong
- Metabolic Diseases Unit Royal Melbourne Hospital Parkville Victoria Australia
- Melbourne Medical School University of Melbourne Parkville Victoria Australia
| | - Drago Bratkovic
- Metabolic Unit Women's and Children's Hospital Adelaide South Australia Australia
| | - Kaustuv Bhattacharya
- Genetic Metabolic Disorders Service The Children's Hospital at Westmead Westmead New South Wales Australia
- Disciplines of Genomic Medicine and Child and Adolescent Health Faculty of Medicine and Health, University of Sydney Sydney New South Wales Australia
| | - Adviye Ayper Tolun
- NSW Biochemical Genetics Service The Children's Hospital at Westmead Westmead New South Wales Australia
- Disciplines of Genomic Medicine and Child and Adolescent Health Faculty of Medicine and Health, University of Sydney Sydney New South Wales Australia
| | - Bruce Bennetts
- Disciplines of Genomic Medicine and Child and Adolescent Health Faculty of Medicine and Health, University of Sydney Sydney New South Wales Australia
- Department of Molecular Genetics Western Sydney Genetics Program, The Children's Hospital at Westmead Westmead New South Wales Australia
| | - Katrina Fisk
- Department of Molecular Genetics Western Sydney Genetics Program, The Children's Hospital at Westmead Westmead New South Wales Australia
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8
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Ryder B, Inbar-Feigenberg M, Glamuzina E, Halligan R, Vara R, Elliot A, Coman D, Minto T, Lewis K, Schiff M, Vijay S, Akroyd R, Thompson S, MacDonald A, Woodward AJM, Gribben JEL, Grunewald S, Belaramani K, Hall M, van der Haak N, Devanapalli B, Tolun AA, Wilson C, Bhattacharya K. New insights into carnitine-acylcarnitine translocase deficiency from 23 cases: Management challenges and potential therapeutic approaches. J Inherit Metab Dis 2021; 44:903-915. [PMID: 33634872 DOI: 10.1002/jimd.12371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 02/19/2021] [Accepted: 02/23/2021] [Indexed: 12/22/2022]
Abstract
Carnitine acyl-carnitine translocase deficiency (CACTD) is a rare autosomal recessive disorder of mitochondrial long-chain fatty-acid transport. Most patients present in the first 2 days of life, with hypoketotic hypoglycaemia, hyperammonaemia, cardiomyopathy or arrhythmia, hepatomegaly and elevated liver enzymes. Multi-centre international retrospective chart review of clinical presentation, biochemistry, treatment modalities including diet, subsequent complications, and mode of death of all patients. Twenty-three patients from nine tertiary metabolic units were identified. Seven attenuated patients of Pakistani heritage, six of these homozygous c.82G>T, had later onset manifestations and long-term survival without chronic hyperammonemia. Of the 16 classical cases, 15 had cardiac involvement at presentation comprising cardiac arrhythmias (9/15), cardiac arrest (7/15), and cardiac hypertrophy (9/15). Where recorded, ammonia levels were elevated in all but one severe case (13/14 measured) and 14/16 had hypoglycaemia. Nine classical patients survived longer-term-most with feeding difficulties and cognitive delay. Hyperammonaemia appears refractory to ammonia scavenger treatment and carglumic acid, but responds well to high glucose delivery during acute metabolic crises. High-energy intake seems necessary to prevent decompensation. Anaplerosis utilising therapeutic d,l-3-hydroxybutyrate, Triheptanoin and increased protein intake, appeared to improve chronic hyperammonemia and metabolic stability where trialled in individual cases. CACTD is a rare disorder of fatty acid oxidation with a preponderance to severe cardiac dysfunction. Long-term survival is possible in classical early-onset cases with long-chain fat restriction, judicious use of glucose infusions, and medium chain triglyceride supplementation. Adjunctive therapies supporting anaplerosis may improve longer-term outcomes.
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Affiliation(s)
- Bryony Ryder
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
- National Metabolic Service, Starship Children's Hospital, Auckland, New Zealand
| | - Michal Inbar-Feigenberg
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Emma Glamuzina
- National Metabolic Service, Starship Children's Hospital, Auckland, New Zealand
| | - Rebecca Halligan
- Department of Inherited Metabolic Disorders, Birmingham Women's and Children's Hospital Foundation Trust, Birmingham, UK
- Department of Metabolic Medicine, Evelina Children's Hospital, London, UK
| | - Roshni Vara
- Department of Metabolic Medicine, Evelina Children's Hospital, London, UK
| | - Aoife Elliot
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, Brisbane, QLD, Australia
| | - David Coman
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, Brisbane, QLD, Australia
- School of Medicine University of Queensland and Griffith University, Brisbane, Queensland, Australia
| | - Tahlee Minto
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, Brisbane, QLD, Australia
| | - Katherine Lewis
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, Brisbane, QLD, Australia
| | - Manuel Schiff
- Reference Centre for Inherited Metabolic Diseases, AP-HP, Necker University Hospital, University of Paris, Paris, France
- INSERM U1163, Institut Imagine, Paris, France
| | - Suresh Vijay
- Department of Inherited Metabolic Disorders, Birmingham Women's and Children's Hospital Foundation Trust, Birmingham, UK
| | - Rhonda Akroyd
- National Metabolic Service, Starship Children's Hospital, Auckland, New Zealand
| | - Sue Thompson
- Department of Metabolic Genetics, Sydney Children's Hospitals' Network NSW, Sydney, New South Wales, Australia
- Faculty of Health and Medical Science, University of Sydney, Sydney, New South Wales, Australia
| | - Anita MacDonald
- Department of Inherited Metabolic Disorders, Birmingham Women's and Children's Hospital Foundation Trust, Birmingham, UK
| | - Abigail J M Woodward
- Department of Nutrition & Dietetics, Evelina London Children's Hospital, London, UK
| | - Joanne E L Gribben
- Department of Nutrition & Dietetics, Evelina London Children's Hospital, London, UK
| | - Stephanie Grunewald
- Metabolic Medicine Department, Great Ormond Street Hospital, Institute of Child Health University College London, NIHR Biomedical Research Centre, London, UK
| | - Kiran Belaramani
- Department of Metabolic Medicine, Hong Kong Children's Hospital, Ngau Tau Kok, Hong Kong
| | - Madeleine Hall
- Departments of Metabolic Medicine & Nutrition, Women's and Children's Hospital, North Adelaide, South Australia, Australia
| | - Natalie van der Haak
- Departments of Metabolic Medicine & Nutrition, Women's and Children's Hospital, North Adelaide, South Australia, Australia
| | - Beena Devanapalli
- Department of Metabolic Genetics, Sydney Children's Hospitals' Network NSW, Sydney, New South Wales, Australia
| | - Adviye Ayper Tolun
- Department of Metabolic Genetics, Sydney Children's Hospitals' Network NSW, Sydney, New South Wales, Australia
| | - Callum Wilson
- National Metabolic Service, Starship Children's Hospital, Auckland, New Zealand
| | - Kaustuv Bhattacharya
- Department of Metabolic Genetics, Sydney Children's Hospitals' Network NSW, Sydney, New South Wales, Australia
- Faculty of Health and Medical Science, University of Sydney, Sydney, New South Wales, Australia
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Sajeev M, Chin S, Ho G, Bennetts B, Sankaran BP, Gutierrez B, Devanapalli B, Tolun AA, Wiley V, Fletcher J, Fuller M, Balasubramaniam S. Challenges in Diagnosing Intermediate Maple Syrup Urine Disease by Newborn Screening and Functional Validation of Genomic Results Imperative for Reproductive Family Planning. Int J Neonatal Screen 2021; 7:ijns7020025. [PMID: 34069211 PMCID: PMC8162326 DOI: 10.3390/ijns7020025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 05/08/2021] [Accepted: 05/12/2021] [Indexed: 11/16/2022] Open
Abstract
Maple syrup urine disease is caused by a deficiency of branched-chain alpha-ketoacid dehydrogenase, responsible for degradation of leucine, isoleucine, and valine. Biallelic pathogenic variants in BCKDHA, BCKDHB, or DBT genes result in enzyme deficiency. We report the case of a female infant who presented with mild gross motor delay at 4 months, and seizures with hypoglycaemia at 5 months. Newborn screening returned total leucine/isoleucine at the 99.5th centile of the population; however, as second-tier testing reported minimal alloisoleucine, the results were considered inconsistent with MSUD. Plasma amino acid and urine organic acid analyses at 5 months were, however, consistent with a diagnosis of MSUD. A brain MRI showed bilateral symmetrical T2 hyperintense signal abnormalities involving white matter, globus pallidus, thalamus, brainstem, and dentate nuclei with restricted diffusion. A repeat MRI 10 months post-dietary-intervention showed the resolution of these changes and progression in myelination. Her clinical phenotype, including protein tolerance, correlated with intermediate MSUD. Molecular analysis of all three genes identified two variants of uncertain significance, c.434-15_434-4del and c.365A>G (p. Tyr122Cys) in the DBT gene. The rate of leucine decarboxylation in fibroblasts was reduced, but not to the extent observed in classical MSUD patients, supporting an intermediate form of MSUD. Previously reported mRNA splicing studies supported a deleterious effect of the c.434-15_434-4del variant. This functional evidence and confirmation that the variants were in trans, permitted their reclassification as pathogenic and likely pathogenic, respectively, facilitating subsequent prenatal testing. This report highlights the challenges in identifying intermediate MSUD by newborn screening, reinforcing the importance of functional studies to confirm variant pathogenicity in this era of molecular diagnostics.
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Affiliation(s)
- Mona Sajeev
- Genetic Metabolic Disorders Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (M.S.); (B.P.S.)
| | - Sharon Chin
- Genetics and Molecular Pathology, SA Pathology at Women’s and Children’s Hospital, North Adelaide, SA 5006, Australia; (S.C.); (J.F.); (M.F.)
| | - Gladys Ho
- Department of Molecular Genetics, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (G.H.); (B.B.)
- Discipline of Genetic Medicine, Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia; (A.A.T.); (V.W.)
| | - Bruce Bennetts
- Department of Molecular Genetics, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (G.H.); (B.B.)
- Discipline of Genetic Medicine, Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia; (A.A.T.); (V.W.)
| | - Bindu Parayil Sankaran
- Genetic Metabolic Disorders Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (M.S.); (B.P.S.)
- The Children’s Hospital at Westmead Clinical School, Faculty of Medicine & Health, Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia
| | - Bea Gutierrez
- NSW Biochemical Genetics Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (B.G.); (B.D.)
| | - Beena Devanapalli
- NSW Biochemical Genetics Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (B.G.); (B.D.)
| | - Adviye Ayper Tolun
- Discipline of Genetic Medicine, Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia; (A.A.T.); (V.W.)
- NSW Biochemical Genetics Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (B.G.); (B.D.)
| | - Veronica Wiley
- Discipline of Genetic Medicine, Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia; (A.A.T.); (V.W.)
- NSW Newborn Screening Programme, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Janice Fletcher
- Genetics and Molecular Pathology, SA Pathology at Women’s and Children’s Hospital, North Adelaide, SA 5006, Australia; (S.C.); (J.F.); (M.F.)
| | - Maria Fuller
- Genetics and Molecular Pathology, SA Pathology at Women’s and Children’s Hospital, North Adelaide, SA 5006, Australia; (S.C.); (J.F.); (M.F.)
- Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia
| | - Shanti Balasubramaniam
- Genetic Metabolic Disorders Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia; (M.S.); (B.P.S.)
- Discipline of Genetic Medicine, Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia; (A.A.T.); (V.W.)
- Correspondence: ; Tel.: +61-2-9845-0201; Fax: +61-2-9845-3121
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10
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Bhattacharya K, Matar W, Tolun AA, Devanapalli B, Thompson S, Dalkeith T, Lichkus K, Tchan M. The use of sodium DL-3-Hydroxybutyrate in severe acute neuro-metabolic compromise in patients with inherited ketone body synthetic disorders. Orphanet J Rare Dis 2020; 15:53. [PMID: 32070364 PMCID: PMC7029565 DOI: 10.1186/s13023-020-1316-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 01/24/2020] [Indexed: 12/30/2022] Open
Abstract
Background Ketone bodies form a vital energy source for end organs in a variety of physiological circumstances. At different times, the heart, brain and skeletal muscle in particular can use ketones as a primary substrate. Failure to generate ketones in such circumstances leads to compromised energy delivery, critical end-organ dysfunction and potentially death. There are a range of inborn errors of metabolism (IEM) affecting ketone body production that can present in this way, including disorders of carnitine transport into the mitochondrion, mitochondrial fatty acid oxidation deficiencies (MFAOD) and ketone body synthesis. In situations of acute energy deficit, management of IEM typically entails circumventing the enzyme deficiency with replenishment of energy requirements. Due to profound multi-organ failure it is often difficult to provide optimal enteral therapy in such situations and rescue with sodium DL-3-hydroxybutyrate (S DL-3-OHB) has been attempted in these conditions as documented in this paper. Results We present 3 cases of metabolic decompensation, one with carnitine-acyl-carnitine translocase deficiency (CACTD) another with 3-hydroxyl, 3-methyl, glutaryl CoA lyase deficiency (HMGCLD) and a third with carnitine palmitoyl transferase II deficiency (CPT2D). All of these disorders are frequently associated with death in circumstance where catastrophic acute metabolic deterioration occurs. Intensive therapy with adjunctive S DL-3OHB led to rapid and sustained recovery in all. Alternative therapies are scarce in these situations. Conclusion S DL-3-OHB has been utilised in multiple acyl co A dehydrogenase deficiency (MADD) in cases with acute neurological and cardiac compromise with long-term data awaiting publication. The use of S DL-3-OHB is novel in non-MADD fat oxidation disorders and contribute to the argument for more widespread use.
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Affiliation(s)
- Kaustuv Bhattacharya
- Disciplines of Genetic Medicine and Child and Adolescent Health, University of Sydney, Sydney, Australia. .,Genetic Metabolic Disorders Service, Sydney Children's Hospital Network, Children's Hospital at Westmead, Locked Bag 4001, Westmead, NSW, 2145, Australia.
| | - Walid Matar
- Department of Neurology, St George Hospital, Kogarah, NSW, Australia
| | | | | | - Sue Thompson
- Disciplines of Genetic Medicine and Child and Adolescent Health, University of Sydney, Sydney, Australia.,Genetic Metabolic Disorders Service, Sydney Children's Hospital Network, Children's Hospital at Westmead, Locked Bag 4001, Westmead, NSW, 2145, Australia
| | - Troy Dalkeith
- Disciplines of Genetic Medicine and Child and Adolescent Health, University of Sydney, Sydney, Australia.,Genetic Metabolic Disorders Service, Sydney Children's Hospital Network, Children's Hospital at Westmead, Locked Bag 4001, Westmead, NSW, 2145, Australia
| | - Kate Lichkus
- Disciplines of Genetic Medicine and Child and Adolescent Health, University of Sydney, Sydney, Australia.,Genetic Metabolic Disorders Service, Sydney Children's Hospital Network, Children's Hospital at Westmead, Locked Bag 4001, Westmead, NSW, 2145, Australia
| | - Michel Tchan
- Disciplines of Genetic Medicine and Child and Adolescent Health, University of Sydney, Sydney, Australia.,Westmead Hospital, University of Sydney, Westmead, Australia
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