Identification, functional analysis, prevalence and treatment of monocarboxylate transporter 8 (<i><scp>MCT</scp>8</i>) mutations in a cohort of adult patients with mental retardation

Abstract

We identified several MCT8 mutations in a cohort of subjects with unexplained MR. We demonstrated the pathogenicity of two missense mutations. The synonymous variant did not affect TH transport. Block-and-replace therapy of one patient reversed the TH abnormalities. Our data suggest a decreased TH secretion rate and an increased T4 to T3 conversion by the type I deiodinase in patients with MCT8 mutations. Our study indicates that MCT8 mutations are a relatively frequent cause of X-linked MR.