The Role of Thyroid Function Tests in Diagnosing Allan-Herndon-Dudley Syndrome Revisited: A Novel Iran-Based Mutation

Introduction: allan-herndon-dudley syndrome (ahds) is a rare x-linked recessiveintellectual disability condition with neuromuscular involvements. altered thyroid functiontests are major milestones in ahds diagnosis. however, due to phenotypic variationsin the levels of thyroid hormones in ahds patients, we believe that the disorder is oftenunderdiagnosed. here, we reported a 3.5-year-old boy with an ahds diagnosis and healthythyroid hormones.methods: whole-exome sequencing followed by data analysis was performed on the patient’ssample. 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 synonymousmissense 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 splicingthrough alteration of an exonic splicing enhancer. to the best of our knowledge, there are only 3similar 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 fordiagnosing ahds. the candidate diagnosis of ahds should be considered in patients withx-linked recessive intellectual disability syndrome with neuromuscular involvements irrespectiveof levels of thyroid hormones; otherwise, it could lead to the under-diagnosis of the disorder.