MUTATION IN THE THYROID-HORMONE RECEPTOR (TR) BETA-GENE (M313T) NOT PREVIOUSLY REPORTED IN 2 UNRELATED FAMILIES WITH RESISTANCE TO THYROID-HORMONE (RTH)

Two families expressing the RTH phenotype and harboring the same mutat ion in the TR beta gene are described. Five and four affected members in each family were investigated as well as a total of 12 unaffected r elatives. The mutation, a T to C transition of nucleotide 1223 in one allele of affected individuals, results in the replacement of the norm al Met for a Thr. Haplotyping revealed that the same mutation develope d in each family independently. Whereas attention deficit hyperactivit y disorder was associated with RTH in 7 of the 9 affected individuals, it was also present in 2 family members without RTH.