MCT8 deficiency, also known as Allan Hernon Dudley Syndrome (AHDS), is a rare congenital encephalopathy that affects male subjects. It is a rare disease with X-linked recessive inheritance. It is characterized by clinical onset during the first months of life with neurodevelopmental delay, axial hypotonia, limbs spasticity, movement disorders (dystonia, hypokinesia, paroxysmal movement disorders), epileptic seizures, global hypotrophy and signs of peripheral thyrotoxicosis. Brain MRI usually shows severe myelination delay which can be misdiagnosed as hypomyelination.
Circulating plasma concentrations of thyroid hormones (T3 and T4) are altered according to a very specific profile characterized by an increase in T3, usually accompanied by a decrease in T4, with high T3/T4 ratio, and normal or subnormal level of pituitary hormone stimulating thyroid hormone production (TSH).
SLC16A2