Noorian S, Hamzehlou S, Rabbani A, Sotoudeh A, Pour Rostami K, Savad S. The Role of Thyroid Function Tests in Diagnosing Allan-herndon-dudley Syndrome Revisited: A Novel Iran-based Mutation. BCN 2021; 12 (4) :563-568
URL:
http://bcn.iums.ac.ir/article-1-1552-en.html
1- Department of Pediatric Endocrinology and Metabolism, Bahonar Hospital, Alborz University of Medical Sciences, Karaj, Iran.
2- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
3- Growth and Development Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran.
Abstract:
Introduction: Allan-Herndon-Dudley Syndrome (AHDS) is a rare X-linked recessive intellectual disability condition with neuromuscular involvements. Altered thyroid function tests are major milestones in AHDS diagnosis. However, due to phenotypic variations in the levels of thyroid hormones in AHDS patients, we believe that the disorder is often underdiagnosed. Here, we reported a 3.5-year-old boy with an AHDS diagnosis and healthy thyroid hormones.
Methods: Whole-Exome sequencing followed by data analysis was performed on the patient’s sample. The mutation was confirmed by Sanger sequencing in the patient and his mother.
Results: We reported a 3.5-year-old boy with AHDS diagnosis and a novel synonymous missense mutation (c. 1026G>A) in the SLC16A2 gene manifesting normal levels of T3, T4, and TSH. The mutation causes no change in amino acid sequence; however, it affects splicing through alteration of an exonic splicing enhancer. To the best of our knowledge, there are only 3 similar reports in the literature reporting AHDS diagnosis and normal levels of thyroid hormones.
Conclusion: The altered levels of thyroid hormones are notable but not necessary markers for diagnosing AHDS. The candidate diagnosis of AHDS should be considered in patients with X-linked recessive intellectual disability syndrome with neuromuscular involvements irrespective of levels of thyroid hormones; otherwise, it could lead to the under-diagnosis of the disorder.
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● A novel mutation (c. 1026G>A) in the SLC16A2 gene causes AHDS.
● The mutation causes no change in amino acid sequence and it only affects splicing.
● Patients with this mutation manifest normal levels of T3, T4, and TSH.
Plain Language Summary
Allan-Herndon-Dudley Syndrome (AHDS) is a rare intellectual disability condition with neuromuscular involvement. Altered thyroid function tests are significant milestones in AHDS diagnosis. However, due to phenotypic variations in the levels of thyroid hormones in AHDS patients, we believe that the disorder is often underdiagnosed. Here, we reported a 3.5-year-old boy with an AHDS diagnosis and healthy thyroid hormones. The DNA sequencing analysis showed that the mutation causes no immediate change in amino acid sequence; however, it affects protein splicing. To the best of our knowledge, there are only three similar reports in the literature reporting AHDS diagnosis and normal levels of thyroid hormones. We conclude that the altered levels of thyroid hormones are notable but not necessary markers for diagnosing AHDS. The candidate diagnosis of AHDS should be considered in patients with X-linked recessive intellectual disability syndrome with neuromuscular involvements irrespective of levels of thyroid hormones; otherwise, it could lead to the under-diagnosis of the disorder.
Type of Study:
News and Reports |
Subject:
Cellular and molecular Neuroscience Received: 2019/07/8 | Accepted: 2020/06/30 | Published: 2021/07/1