Thyroid Hormone “Sobetirome” Identified As A Treatment for Allan-Herndon-Dudley Syndrome

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A group of scientists from the Oregon Health & Science University, in Portland, the Spanish  Center of Scientific Investigations (CSIC), and the Autonomous University of Madrid, in Spain, have identified the thyroid hormone “sobetirome” as a possible drug to treat Allan-Herndon-Dudley syndrome which is a rare disease caused by mutations in the thyroid hormone transporter MCT8, which only affects males.

Patients present with global developmental delay, profound intellectual disability, lack of language abilities and severe neuromotor disorders, such as hypotonia or weak muscle tone, which evolves into spastic tetraplegia. Also, they also suffer alterations in the levels of thyroid hormones in the blood, since they present high levels of thyroid hormone T3 which generates peripheral hyperthyroidism.

At brain level, the lack of MCT8 in the blood-brain barrier prevents thyroid hormones to be transported within the brain, generating brain hypothyroidism. Therefore, MCT8 deficient patients present a paradoxical situation of peripheral hyperthyroidism and cerebral hypothyroidism.

“Sobetirome” is a synthetic drug that has a different chemical structure from thyroid hormone T3, but can bind to thyroid hormone receptors and trigger the same type of responses in cells.

Allan-Herndon-Dudley syndrome might be cured with the thyroid hormone “sobetirome”

“In our study we treated MCT8-deficient mice with sobetirome, to assess whether this analog hormone can improve peripheral hyperthyroidism and access the brain under MCT8-deficient conditions to generate similar responses to thyroid hormone T3,” explained the study’s authors in the medical journal Thyroid.

Explicitly, the data have revealed that treatment with “sobetirome” in mice with deficient MCT8 drastically decreases the levels of T3 in blood. And, in the opinion of the researchers, is even “more important,” as the “sobetirome” can access the brain and regulate the expression of some genes that are typically controlled by T3.

“Therefore, our studies indicate that the thyroid hormone analog ‘sobetirome’ has the potential to improve peripheral hyperthyroidism and neurological alterations characteristic of Allan-Herndon-Dudley syndrome,” the authors have concluded.