[P2-37] Allan-Herndon-Dudley Syndrome (AHDS) With Atypical Features, Case Report And A Literature Review
Allan-Herndon-Dudley syndrome (AHDS) is rare X-linked recessive condition. AHDS is caused by mutations in the solute carrier family 16 member 2 (SLC16A2) gene, encoding for monocarboxylate transporter 8 (MCT8), a thyroid hormone transporter. Clinical features include initial hypotonia followed by spasticity, dystonia and intellectual disability. All affected males have high triiodothyronine (T3), low-normal thyroxine (T4), and normal-high thyroid stimulating hormone (TSH). Here, we report a family of 2 brothers with AHDS due to a novel missense mutation in SLC16A2 along with unique finding of over-myelination in magnetic resonance imaging (MRI) and atypical thyroid profile. In this case report and literature review, we highlight key clinical and radiological features of AHDS that was reported since 1944, with comparison to our case. Although follow-up MRI of the brain showed accelerated myelination, there was no clinical improvement. SLC16A2 mutations should be suspected even when there is atypical thyroid profile and imaging findings.