Mutations in the gene encoding paired box domain (PAX8) are not a frequent cause of congenital hypothyroidism (CH) in Iranian patients with thyroid dysgenesis.

OBJECTIVE Congenital hypothyroidism (CH) may be caused by defects in the thyroid or in one of the stages in the synthesis of thyroid hormones. Thyroid dysgenesis may be associated with mutation in the paired box transcription factor 8 (PAX8) gene. We attempted to screen PAX8 gene mutation in 50 CH patients with thyroid dysgenesis. SUBJECTS AND METHODS The patients were classified in two groups as agenesis and ectopic based on biochemical and para clinical tests. By employing PCR, Single Strand Conformation Polymorphism (SSCP) and sequencing, exons 3 to 12 of PAX8 gene with their exon-intron boundaries were studied. RESULTS No mutation was found in these patients in any of the exons. CONCLUSION Our results, once again, indicate that the PAX8 mutation rate is very low and can only explain a minority of the cases. Therefore, it is highly needed to further investigate the genes controlling development and function of thyroid.