A Novel c.826G>A Mutation in a Boy with Allan-Herndon-Dudley Syndrome: Clinical Significance of Thyroid Function Tests in Developmental Delay of Unknown Origin / 대한소아신경학회지

ABSTRACT

Allan-Herndon-Dudley syndrome (AHDS) is an X-linked intellectual disability caused by monocarboxylate transporter 8 (MCT8) deficiency. AHDS manifests in global developmental delay, axial hypotonia, quadriplegia, movement disorders in male patients, and most of them show the delayed or hypomyelination on brain magnetic resonance images. Typically, Triiodothyronine (T3) levels are markedly elevated, thyroid stimulating hormone (TSH) levels are normal or elevated, and free thyroxine (T4) levels are normal or decreased. In AHDS patients, early neurological manifestations are easily mistaken as cerebral palsy with unknown origin. Here, we present a novel c.826G>A mutation in a boy with severe axial hypotonia, limb dystonia and developmental delay. Thyroid function test including TSH, T3, and free T4 levels was the important clue for the diagnosis of AHDS of the patient.