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Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination?

Monocarboxylate transporter 8 (MCT8) deficiency or the Allan-Herndon-Dudley Syndrome (AHDS) is an X-linked psychomotor disability syndrome with around 320 clinical cases described worldwide. SLC16A2 gene mutations, encoding the thyroid hormone (TH) transporter MCT8, result in intellectual disability...

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Autores principales: Vancamp, Pieter, Demeneix, Barbara A., Remaud, Sylvie
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7237703/
https://www.ncbi.nlm.nih.gov/pubmed/32477268
http://dx.doi.org/10.3389/fendo.2020.00283
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author Vancamp, Pieter
Demeneix, Barbara A.
Remaud, Sylvie
author_facet Vancamp, Pieter
Demeneix, Barbara A.
Remaud, Sylvie
author_sort Vancamp, Pieter
collection PubMed
description Monocarboxylate transporter 8 (MCT8) deficiency or the Allan-Herndon-Dudley Syndrome (AHDS) is an X-linked psychomotor disability syndrome with around 320 clinical cases described worldwide. SLC16A2 gene mutations, encoding the thyroid hormone (TH) transporter MCT8, result in intellectual disability due to impaired TH uptake in the developing brain. MCT8 deficiency is a multi-organ affecting disease with a predominant neuronal cell-based pathology, with the glial component inadequately investigated. However, deficiency in myelin, a key component of white matter (WM) enabling fast nerve conduction, is a TH-dependent hallmark of the disease. Nevertheless, analysis of the myelin status in AHDS patients has led to conflicting interpretations. The majority of individual case studies reported delayed myelination, that was restored later in life. In contrast, post-mortem studies and high-resolution MRIs detected WM (micro-) abnormalities throughout adolescence, suggesting permanent hypomyelination. Thus, interpretations vary depending on methodology to investigate WM microstructure. Further, it is unknown whether the mutation within the MCT8 is linked to the severity of the myelin deficiency. Consequently, terminology is inconsistent among reports, and AHDS is occasionally misdiagnosed as another WM disorder. The evolutionary conserved TH signaling pathway that promotes the generation of myelinating oligodendrocytes enabled deciphering how the lack of MCT8 might affect myelinogenesis. Linking patient findings on myelination to those obtained from models of MCT8 deficiency revealed underlying pathophysiological mechanisms, but knowledge gaps remain, notably how myelination progresses both spatially and temporally in MCT8 deficiency. This limits predicting how myelin integrity might benefit therapeutically, and when to initiate. A recurrent observation in clinical trials is the absence of neurological improvement. Testing MCT8-independent thyromimetics in models, and evaluating treatments used in other demyelinating diseases, despite different etiologies, is crucial to propose new therapeutic strategies combatting this devastating disease.
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spelling pubmed-72377032020-05-29 Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination? Vancamp, Pieter Demeneix, Barbara A. Remaud, Sylvie Front Endocrinol (Lausanne) Endocrinology Monocarboxylate transporter 8 (MCT8) deficiency or the Allan-Herndon-Dudley Syndrome (AHDS) is an X-linked psychomotor disability syndrome with around 320 clinical cases described worldwide. SLC16A2 gene mutations, encoding the thyroid hormone (TH) transporter MCT8, result in intellectual disability due to impaired TH uptake in the developing brain. MCT8 deficiency is a multi-organ affecting disease with a predominant neuronal cell-based pathology, with the glial component inadequately investigated. However, deficiency in myelin, a key component of white matter (WM) enabling fast nerve conduction, is a TH-dependent hallmark of the disease. Nevertheless, analysis of the myelin status in AHDS patients has led to conflicting interpretations. The majority of individual case studies reported delayed myelination, that was restored later in life. In contrast, post-mortem studies and high-resolution MRIs detected WM (micro-) abnormalities throughout adolescence, suggesting permanent hypomyelination. Thus, interpretations vary depending on methodology to investigate WM microstructure. Further, it is unknown whether the mutation within the MCT8 is linked to the severity of the myelin deficiency. Consequently, terminology is inconsistent among reports, and AHDS is occasionally misdiagnosed as another WM disorder. The evolutionary conserved TH signaling pathway that promotes the generation of myelinating oligodendrocytes enabled deciphering how the lack of MCT8 might affect myelinogenesis. Linking patient findings on myelination to those obtained from models of MCT8 deficiency revealed underlying pathophysiological mechanisms, but knowledge gaps remain, notably how myelination progresses both spatially and temporally in MCT8 deficiency. This limits predicting how myelin integrity might benefit therapeutically, and when to initiate. A recurrent observation in clinical trials is the absence of neurological improvement. Testing MCT8-independent thyromimetics in models, and evaluating treatments used in other demyelinating diseases, despite different etiologies, is crucial to propose new therapeutic strategies combatting this devastating disease. Frontiers Media S.A. 2020-05-13 /pmc/articles/PMC7237703/ /pubmed/32477268 http://dx.doi.org/10.3389/fendo.2020.00283 Text en Copyright © 2020 Vancamp, Demeneix and Remaud. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Endocrinology
Vancamp, Pieter
Demeneix, Barbara A.
Remaud, Sylvie
Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination?
title Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination?
title_full Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination?
title_fullStr Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination?
title_full_unstemmed Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination?
title_short Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination?
title_sort monocarboxylate transporter 8 deficiency: delayed or permanent hypomyelination?
topic Endocrinology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7237703/
https://www.ncbi.nlm.nih.gov/pubmed/32477268
http://dx.doi.org/10.3389/fendo.2020.00283
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