Erratum: Clinical and Endocrine Features of Two Allan-Herndon-Dudley Syndrome Patients with Monocarboxylate Transporter 8 Mutations

The monocarboxylate transporter 8 <i>(MCT8)</i> gene, located on chromosome Xq13.2, encodes a thyroid hormone transporter that is involved in triiodothyronine (T3) uptake into central neurons. <i>MCT8</i> mutations cause an X-linked syndromic disorder known as Allan-Herndon-Dudley syndrome (AHDS) that is characterized by severe psychomotor delays, abnormal thyroid function, and hypomyelinated leukodystrophies. We identified 2 AHDS patients with developmental delays, truncal hypotonia, and spastic paraplegia. These patients presented with psychomotor retardation and characteristic thyroid function abnormalities, such as elevated T3 and low T4 levels. Direct <i>MCT8</i> sequencing identified heterozygous mutations in each patient: p.I114N and p.A224V, respectively. Because it is difficult to suspect AHDS solely according to neurological features, thyroid function, including the T3 level, should be screened in male patients with X-linked mental retardation. Although the clinical features of hypothyroidism cannot be improved by only administering levothyroxine treatment, early diagnosis, management, and appropriate genetic counseling should be provided to at-risk families.