TTF1 and hypothyroidism, congenital, nongoitrous, 2: Additionally, 21.21% (28/132) of mutations were related to thyroid dysgenesis [TSHR (n = 19), TTF1 (n = 5), TTF2 (n = 1), PAX8 (n = 2), and NKX2-5 (n = 1)].