Finally, 4PBA also restores cell surface expression of monocarboxylate transporter 8 (MCT8, a thyroid hormone transporter) in patients with Allan-Herndon-Dudley syndrome, a condition characterized by mutations in MCT8 resulting in retention of the transporter in the ER (Braun and Schweizer, 2017). This evidence concerns the gene SLC16A2 and Allan-Herndon-Dudley syndrome.