1
|
Bauer AJ, Auble B, Clark AL, Hu TY, Isaza A, McNerney KP, Metzger DL, Nicol L, Pierce SR, Sidlow R. Unmet patient needs in monocarboxylate transporter 8 (MCT8) deficiency: a review. Front Pediatr 2024; 12:1444919. [PMID: 39132310 PMCID: PMC11310894 DOI: 10.3389/fped.2024.1444919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 07/03/2024] [Indexed: 08/13/2024] Open
Abstract
Monocarboxylate transporter 8 (MCT8) deficiency is a rare, X-linked disorder arising from mutations in the SLC16A2 gene and resulting from dysfunctional thyroid hormone transport. This disorder is characterized by profound neurodevelopmental delay and motor disability due to a lack of thyroid hormone in the brain, and coexisting endocrinological symptoms, due to chronic thyrotoxicosis, resulting from elevated thyroid hormone outside the central nervous system (CNS). In February 2024, we reviewed the published literature to identify relevant articles reporting on the current unmet needs of patients with MCT8 deficiency. There are several main challenges in the diagnosis and treatment of MCT8 deficiency, with decreased awareness and recognition of MCT8 deficiency among healthcare professionals (HCPs) associated with misdiagnosis and delays in diagnosis. Diagnostic delay may also be attributed to other factors, including the complex symptomology of MCT8 deficiency only becoming apparent several months after birth and pathognomonic serum triiodothyronine (T3) testing not being routinely performed. For patients with MCT8 deficiency, multidisciplinary team care is vital to optimize the support provided to patients and their caregivers. Although there are currently no approved treatments specifically for MCT8 deficiency, earlier identification and diagnosis of this disorder enables earlier access to supportive care and developing treatments focused on improving outcomes and quality of life for both patients and caregivers.
Collapse
Affiliation(s)
- Andrew J. Bauer
- The Thyroid Center, Division of Endocrinology and Diabetes, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Bethany Auble
- Medical College of Wisconsin, Children’s Wisconsin, Milwaukee, WI, United States
| | - Amy L. Clark
- Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, MO, United States
- Department of Pediatric Endocrinology and Diabetes, SSM Health Cardinal Glennon, St. Louis, MO, United States
| | - Tina Y. Hu
- Department of Pediatrics, Division of Endocrinology, University of California San Francisco, San Francisco, CA, United States
| | - Amber Isaza
- The Thyroid Center, Division of Endocrinology and Diabetes, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Kyle P. McNerney
- Diabetes Education Program, Washington University in St. Louis, St. Louis, MO, United States
| | - Daniel L. Metzger
- The Endocrinology & Diabetes Unit, British Columbia Children’s Hospital, Vancouver, BC, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
| | - Lindsey Nicol
- Department of Pediatric Endocrinology, Oregon Health & Science University Doernbecher Children’s Hospital, Portland, OR, United States
- Division of Endocrinology, Oregon Health & Science University, Portland, OR, United States
| | - Samuel R. Pierce
- Division of Rehabilitation Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Richard Sidlow
- Department of Medical Genetics and Metabolism, Valley Children’s Hospital, Madera, CA, United States
| |
Collapse
|
2
|
Ferrer J, Dimitrova N. Transcription regulation by long non-coding RNAs: mechanisms and disease relevance. Nat Rev Mol Cell Biol 2024; 25:396-415. [PMID: 38242953 PMCID: PMC11045326 DOI: 10.1038/s41580-023-00694-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2023] [Indexed: 01/21/2024]
Abstract
Long non-coding RNAs (lncRNAs) outnumber protein-coding transcripts, but their functions remain largely unknown. In this Review, we discuss the emerging roles of lncRNAs in the control of gene transcription. Some of the best characterized lncRNAs have essential transcription cis-regulatory functions that cannot be easily accomplished by DNA-interacting transcription factors, such as XIST, which controls X-chromosome inactivation, or imprinted lncRNAs that direct allele-specific repression. A growing number of lncRNA transcription units, including CHASERR, PVT1 and HASTER (also known as HNF1A-AS1) act as transcription-stabilizing elements that fine-tune the activity of dosage-sensitive genes that encode transcription factors. Genetic experiments have shown that defects in such transcription stabilizers often cause severe phenotypes. Other lncRNAs, such as lincRNA-p21 (also known as Trp53cor1) and Maenli (Gm29348) contribute to local activation of gene transcription, whereas distinct lncRNAs influence gene transcription in trans. We discuss findings of lncRNAs that elicit a function through either activation of their transcription, transcript elongation and processing or the lncRNA molecule itself. We also discuss emerging evidence of lncRNA involvement in human diseases, and their potential as therapeutic targets.
Collapse
Affiliation(s)
- Jorge Ferrer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain.
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
| | - Nadya Dimitrova
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.
| |
Collapse
|
3
|
Mura E, Parazzini C, Tonduti D. Rare forms of hypomyelination and delayed myelination. HANDBOOK OF CLINICAL NEUROLOGY 2024; 204:225-252. [PMID: 39322381 DOI: 10.1016/b978-0-323-99209-1.00002-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2024]
Abstract
Hypomyelination is defined by the evidence of an unchanged pattern of deficient myelination on two MRIs performed at least 6 months apart in a child older than 1 year. When the temporal criteria are not fulfilled, and the follow-up MRI shows a progression of the myelination even if still not adequate for age, hypomyelination is excluded and the pattern is instead consistent with delayed myelination. This can be mild and nonspecific in some cases, while in other cases there is a severe delay that in the first disease stages could be difficult to differentiate from hypomyelination. In hypomyelinating leukodystrophies, hypomyelination is due to a primary impairment of myelin deposition, such as in Pelizaeus Merzabcher disease. Conversely, myelin lack is secondary, often to primary neuronal disorders, in delayed myelination and some condition with hypomyelination. Overall, the group of inherited white matter disorders with abnormal myelination has expanded significantly during the past 20 years. Many of these disorders have only recently been described, for many of them only a few patients have been reported and this contributes to make challenging the diagnostic process and the interpretation of Next Generation Sequencing results. In this chapter, we review the clinical and radiologic features of rare and lesser known forms of hypomyelination and delayed myelination not mentioned in other chapters of this handbook.
Collapse
Affiliation(s)
- Eleonora Mura
- Unit of Pediatric Neurology, Department of Biomedical and Clinical Sciences, V. Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy; C.O.A.L.A (Center for Diagnosis and Treatment of Leukodystrophies), V. Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Cecilia Parazzini
- C.O.A.L.A (Center for Diagnosis and Treatment of Leukodystrophies), V. Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy; Pediatric Radiology and Neuroradiology Department, V. Buzzi Children's Hospital, Milan, Italy
| | - Davide Tonduti
- Unit of Pediatric Neurology, Department of Biomedical and Clinical Sciences, V. Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy; C.O.A.L.A (Center for Diagnosis and Treatment of Leukodystrophies), V. Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy.
| |
Collapse
|
4
|
Rosspopoff O, Cazottes E, Huret C, Loda A, Collier A, Casanova M, Rugg-Gunn P, Heard E, Ouimette JF, Rougeulle C. Species-specific regulation of XIST by the JPX/FTX orthologs. Nucleic Acids Res 2023; 51:2177-2194. [PMID: 36727460 PMCID: PMC10018341 DOI: 10.1093/nar/gkad029] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 12/08/2022] [Accepted: 01/11/2023] [Indexed: 02/03/2023] Open
Abstract
X chromosome inactivation (XCI) is an essential process, yet it initiates with remarkable diversity in various mammalian species. XIST, the main trigger of XCI, is controlled in the mouse by an interplay of lncRNA genes (LRGs), some of which evolved concomitantly to XIST and have orthologues across all placental mammals. Here, we addressed the functional conservation of human orthologues of two such LRGs, FTX and JPX. By combining analysis of single-cell RNA-seq data from early human embryogenesis with various functional assays in matched human and mouse pluripotent stem- or differentiated post-XCI cells, we demonstrate major functional differences for these orthologues between species, independently of primary sequence conservation. While the function of FTX is not conserved in humans, JPX stands as a major regulator of XIST expression in both species. However, we show that different entities of JPX control the production of XIST at various steps depending on the species. Altogether, our study highlights the functional versatility of LRGs across evolution, and reveals that functional conservation of orthologous LRGs may involve diversified mechanisms of action. These findings represent a striking example of how the evolvability of LRGs can provide adaptative flexibility to constrained gene regulatory networks.
Collapse
Affiliation(s)
- Olga Rosspopoff
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, F-75013 Paris, France
| | - Emmanuel Cazottes
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, F-75013 Paris, France
| | - Christophe Huret
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, F-75013 Paris, France
| | - Agnese Loda
- Directors' research, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Amanda J Collier
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
- Wellcome Trust – Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK
| | - Miguel Casanova
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, F-75013 Paris, France
| | - Peter J Rugg-Gunn
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
- Wellcome Trust – Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK
| | - Edith Heard
- Directors' research, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Collège de France, Paris, France
| | | | - Claire Rougeulle
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, F-75013 Paris, France
| |
Collapse
|
5
|
Olivati C, Favilla BP, Freitas EL, Santos B, Melaragno MI, Meloni VA, Piazzon F. Allan-Herndon-Dudley syndrome in a female patient and related mechanisms. Mol Genet Metab Rep 2022; 31:100879. [PMID: 35782622 PMCID: PMC9248228 DOI: 10.1016/j.ymgmr.2022.100879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 11/30/2022] Open
Abstract
Allan-Herndon-Dudley syndrome (AHDS) is characterized by neuropsychomotor developmental delay/intellectual disability, neurological impairment with a movement disorder, and an abnormal thyroid hormone profile. This disease is an X-linked disorder that mainly affects men. We described a female patient with a de novo variant in the SLC16A2 gene, a milder AHDS phenotype, and a skewed X chromosome inactivation profile. We discuss the mechanisms associated with the expression of the phenotypic characteristics in female patients, including SLC16A2 gene variants and cytogenomic alterations, as well as preferential inactivation of the normal X chromosome.
Collapse
Affiliation(s)
- Caroline Olivati
- Rare Rosy Clinic, São Paulo, Brazil
- Fleury Medicina e Saúde, São Paulo, Brazil
- Corresponding author at: Rare Rosy Clinic, Rua Borges Lagoa, 1080, CEP 04038-020 São Paulo, SP, Brazil.
| | - Bianca Pereira Favilla
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil
| | | | | | - Maria Isabel Melaragno
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Vera Ayres Meloni
- Rare Rosy Clinic, São Paulo, Brazil
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Flavia Piazzon
- Rare Rosy Clinic, São Paulo, Brazil
- Neuromuscular Reference Center, Department of Pediatrics, University Hospital Liège & University of Liège, Belgium
- Neurometabolic Unit, University of São Paulo, São Paulo, Brazil
| |
Collapse
|
6
|
Zhang Q, Yang Q, Zhou X, Qin Z, Yi S, Luo J. Characteristics of Allan-Herndon-Dudley Syndrome in Chinese children: Identification of two novel pathogenic variants of the SLC16A2 gene. Front Pediatr 2022; 10:1050023. [PMID: 36458135 PMCID: PMC9705582 DOI: 10.3389/fped.2022.1050023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/02/2022] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE The aim of this study was to identify causative variants associated with Allan-Herndon-Dudley syndrome (AHDS) in two unrelated Chinese families, and to determine their potential pathogenicity. We also summarized the core clinical symptoms of AHDS by reviewing the related literature. METHODS Genomic DNA was isolated from the peripheral blood of AHDS patients and their family members. Whole exome sequencing (WES) was performed on the proband from each family to identify the candidate variants. Subsequently, Sanger sequencing was used to verify the identified candidate variants and to assess co-segregation among the available family members. In silico prediction combined with 3D protein modeling was conducted to predict the functional effects of the variants on the encoded protein. RESULTS Two novel hemizygous variants of SLC16A2, c.1111_1112insGTCTTGT (Gly375fs*6) and c.942delA (Val315fs*28), were detected in two patients. We compared the clinical symptoms of the patients with all patients with AHDS reported in China and those reported in the literature. While both our patients presented symptoms mostly consistent with AHDS, Patient 1 had no abnormal brain structure and thyroid function, and yet showed other symptoms including lactic aciduria, conjunctival hyperemia, vomiting, laryngeal stridor, low immunoglobulin and iron levels. CONCLUSIONS This study expands the mutation spectrum of AHDS and has clinical value for variant-based prenatal and postnatal screening for this condition. Doctors often have difficulty identifying AHDS by using clinical symptoms. WES can help to identify specific disorder when diagnosis cannot be made based on symptoms alone.
Collapse
Affiliation(s)
- Qiang Zhang
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Qi Yang
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Xunzhao Zhou
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Zailong Qin
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Shang Yi
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Jingsi Luo
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| |
Collapse
|