Intermittent Esotropia in 4 Patients With Allan-Herndon-Dudley Syndrome.

Allan-Herndon-Dudley syndrome is a rare X-linked neurologic condition caused by mutations in monocarboxylate transporter 8 ( MCT8), which leads to deficient thyroid hormone transport. Typical features include severe cognitive impairment, truncal hypotonia, spastic paraplegia, weakness, and speech difficulties. Minimal literature exists describing the ocular findings in patients with Allan-Herndon-Dudley syndrome. We describe 4 male siblings affected with Allan-Herndon-Dudley syndrome with a novel nonsense mutation (Q90X) in the MCT8 protein. All affected siblings presented with classic findings of Allan-Herndon-Dudley syndrome, and each of the siblings also developed intermittent esotropia. This group of affected siblings represents the first consistent documentation of strabismus in Allan-Herndon-Dudley syndrome, suggesting a possible association between this clinical finding and the neurologic syndrome.