Allan-Herndon-Dudley Syndrome (AHDS), an X linked condition, is characterized by 
congenital hypotonia that progresses to spasticity with severe psychomotor 
delays, in combination with altered thyroid hormone levels, in particular, high 
serum T3 levels. Recently, this disease was proved to be caused by mutations in 
SLC16A2 coding for the monocarboxylate thyroid hormone transporter 8 (MCT8). 
Here we describe a 26-year -old Japanese patient with AHDS who had deletion of 
exon 3 of SLC16A2.