Resistance to thyrotropin (TSH) (RTSH; defined by elevated TSH and a normal or hypoplastic thyroid gland) can be caused by mutations in genes encoding the TSH receptor and PAX8, and it has been linked to a locus on chromosome 15.
The shared clinical picture caused by these defects is a variable degree of thyrotropin resistance (RTSH [MIM 275200]), accompanied in its severe form by thyroid gland hypoplasia.