[Familial congenital hypothyroidism due to loss of function mutation of the thyrotropin receptor (resistance to thyrotropin)].

The TSH receptor belongs to a subfamily of G protein-coupled receptors that mediates the effect of TSH in thyroid development and hormone synthesis. Similarly to many other G protein--coupled receptors, both gain and loss of function mutations have been found in the TSH receptor. Loss of function mutations in the TSH receptor gene were first described in three siblings with resistance to TSH in 1995. To date, 13 pedigrees with TSH receptor mutations of loss of function type have been reported. The phenotype of the patients varies from euthyroid hyperthyrotropinemia to severe congenital hypothyroidism with thyroid hypoplasia.