Normal function of the thyroid gland is the cornerstone of a child's mental development and physical growth. We describe a Finnish family, in which the diagnosis of three brothers became clear after investigations that lasted for more than 30 years. Two of the sons have already died. DNA analysis of the third one, a 16-year-old boy, revealed in exome sequencing of the complete X chromosome a mutation in the SLC16A2 gene, i.e. MCT8, coding for a thyroid hormone transport protein. Allan-Herndon-Dudley syndrome was thus shown to be the cause of multiple disabilities.
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Eur Thyroid J
January 2025
H Heuer, Department of Endocrinology, Diabetes and Metabolism, University of Duisburg-Essen, Essen, Germany.
Objective: Mutations in the thyroid hormone (TH) transporter monocarboxylate transporter 8 (MCT8) cause Allan-Herndon-Dudley syndrome (AHDS), a severe form of psychomotor retardation with muscle hypoplasia and spastic paraplegia as key symptoms. These abnormalities have been attributed to an impaired TH transport across brain barriers and into neural cells thereby affecting brain development and function. Likewise, Mct8/Oatp1c1 (organic anion transporting polypeptide 1c1) double knockout (M/Odko) mice, a well-established murine AHDS model, display a strongly reduced TH passage into the brain as well as locomotor abnormalities.
View Article and Find Full Text PDFEur J Pediatr
December 2024
Department of Pediatric Endocrinology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
Unlabelled: Allan-Herndon-Dudley syndrome is a neurodevelopmental disorder characterized by motor and intellectual disabilities. Despite its rarity, there has been a rise in interest due to ongoing research and emerging therapy suggestions. In this multicenter, retrospective, cross-sectional study, the genetic characteristics and clinical data of twenty-one cases of genetically confirmed MCT8 deficiency were evaluated.
View Article and Find Full Text PDFNeuropediatrics
January 2025
Division of Pediatric Endocrinology and Diabetology, Department of Pediatrics and Adolescent Medicine, KJF Klinikum Josefinum, Augsburg, Germany.
Patients with MCT8 deficiency often present with underweight and are prone to frequent pulmonary infections, including aspiration pneumonia. Despite commonly reported swallowing difficulties in this population, specific dysphagia symptoms have not been well-documented. We conducted a flexible endoscopic evaluation of swallowing (FEES) on a young boy diagnosed with MCT8 deficiency, who exhibited recurrent pulmonary infections and failed to achieve substantial weight gain despite an oral energy intake appropriate for his age and height.
View Article and Find Full Text PDFMethods Mol Biol
November 2024
Laboratory of Thyroid Hormones and Central Nervous System, Department of Neurological Diseases and Aging, Instituto de Investigaciones Biomédicas Sols-Morreale, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Madrid, Spain.
Magnetic resonance imaging (MRI) techniques have emerged as powerful tools for unraveling the pathophysiology of rare diseases, mainly due to their pivotal role in early diagnosis, disease characterization, and treatment monitoring in a non-invasive manner. In this chapter, we will review two essential MRI tools used for studying and evaluating the pathophysiology of Allan-Herndon-Dudley Syndrome or MCT8 deficiency, a rare disease caused by inactivating mutations in the SLC16A2 gene, encoding for the thyroid hormone-specific transmembrane transporter MCT8. These two MRI techniques are time-of-flight magnetic resonance angiography (TOF-MRA) and diffusion tensor imaging (DTI).
View Article and Find Full Text PDFEur Thyroid J
December 2024
Department of Endocrinology, Diabetes & Metabolism, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
Patients with an inactive thyroid hormone (TH) transporter MCT8 (Allan-Herndon-Dudley Syndrome, AHDS) display severe neurological impairments and motor disabilities, indicating an indispensable function of MCT8 in facilitating TH access to the human brain. Consequently, the CNS of AHDS patients appears to be in a TH deficient state, which greatly compromises proper neural development and function. Another hallmark of this disease is that patients exhibit elevated serum T3 levels, leading to a hyperthyroid situation in peripheral tissues.
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