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Gene: SLC16A2

Green List (high evidence)

The condition is characterized in males by neurologic findings (hypotonia and feeding difficulties in infancy, developmental delay / intellectual disability ranging from mild to profound) and later-onset pyramidal signs, extrapyramidal findings (dystonia, choreoathetosis, paroxysmal movement disorder, hypokinesia, masked facies), and seizures, often with drug resistance. Additional findings can include dysthyroidism (manifest as poor weight gain, reduced muscle mass, and variable cold intolerance, sweating, elevated heart rate, and irritability) and pathognomonic thyroid test results. Most heterozygous females are not clinically affected but may have minor thyroid test abnormalities.
Gene previously known as MCT8. >160 affected individuals have been identified.
Large deletions in SLC16A2 are assumed to result in complete inactivation of MCT8 and a consequently severe phenotype. While the most frequent large SLC16A2 deletions are of exon 1, deletions of exons 2-4, exons 2-6, exon 3, exons 3-4, and exon 6 have also been reported. About 15% of cases are due to deletions.

Created: 1 Jan 2025, 11:11 p.m. | Last Modified: 1 Jan 2025, 11:11 p.m.

Panel Version: 1.984

Mode of inheritance
X-LINKED: hemizygous mutation in males, biallelic mutations in females

Phenotypes
Allan-Herndon-Dudley syndrome, MIM #300523

Publications

• PMID: 20301789
• 20083155
• 15980113