Novel pathogenic mechanism suggested by ex vivo analysis of MCT8 (SLC16A2) mutations
Monocarboxylate transporter 8 (MCT8; approved symbol SLC16A2) facilitates cellular uptake and efflux of 3,3',5-triiodothyronine (T3). Mutations in MCT8 arc associated with severe psychomotor retardation, high serum T3 and low 3,3',5'-triiodothyronine (rT3) levels. Here we report three novel MCT8 mutations. Two subjects with the F501 del mutation have mild psychomotor retardation with slightly elev