ABSENCE OF MUTATIONS IN THE GENE ENCODING THYROID TRANSCRIPTION FACTOR-I (TTF-1) IN PATIENTS WITH THYROID DYSGENESIS

Thyroid transription factor-1 (TTF-1) is a homeodomain-containing nucl ear transcription factor, important in regulation of the thyroid-speci fic genes thyroglobulin (Tg), thyroperoxidase (TPO), and thyrotropin r eceptor (TSHR). TTF-1 is an early biochemical marker of thyroid differ entiation, essential for thyroid development and maintenance of the th yroid differentiated state. It is possible that mutations in titf1 gen e encoding TTF-1 could result in failure of the thyroid gland to devel op. Single strand conformation polymorphism (SSCP) was used to detect the presence of titf1 gene mutation in a group of 15 patients with con genital hypothyroidism. The etiology of the congenital hypothyroidism included thyroid agenesis (9), sublingual ectopic thyroid (4), and sev ere hypoplasia (2). The analysis did not identify any titf1 gene mutat ion, among these patients. These results rule out the presence of titf 1 mutations, at least in the coding region, in our thyroid dysgenesis patients. Mutations in titf1 coding region may be an extremely rare ev ent, and was not detected in our small sample size or, alternatively, such a mutant might even be viable since TTF-1 plays an important role in lung, brain, and pituitary development.