European Journal of Pediatrics

, Volume 169, Issue 5, pp 573–575 | Cite as

Elevated TSH levels in a mentally retarded boy

Original Paper


The Allan–Herndon–Dudley syndrome (AHDS; MIM 300523) of X-linked mental retardation and hypotonia is caused by mutations in a thyroid hormone transporter gene—the monocarboxylate transporter 8 (MCT8 also known as SLC16A2) gene. A 23-month-old boy with severe developmental delay, hypotonia, recurrent emesis, and irritability is described. He was diagnosed with hypothyroidism at the age of 4 months. However, T3 level was elevated. Molecular analysis of the MCT8 gene detected a single base duplication in exon 5 c.1614dupC (p.Ile539fs), consistent with a diagnosis of AHDS. While T3 is the best marker for this disorder, elevations in TSH should alert to the diagnosis.


Triiodothyronine Hypothyroidism Allan–Herndon–Dudley syndrome X-linked mental retardation MCT 8 







Thyroid stimulating hormone


Monocarboxylate transporter 8


Allan–Herndon–Dudley syndrome


Conflict of interest

There is no conflict of interest. No funding was required for this study.


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.National Centre for Inherited Metabolic DisordersChildren’s University Hospital and Our Lady’s Children’s HospitalDublinIreland
  2. 2.National Centre for Medical GeneticsOur Lady’s Children’s HospitalDublinIreland

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