Congenital hypothyroidism is a condition characterized by inadequate availability of active thyroid hormone to target tissues in the newborn period. It can be sporadic or inherited. Up to 85% of cases of congenital hypothyroidism are the consequence of thyroid dysgenesis due to an absent (athyreosis), abnormally located (ectopic), or a small (hypoplastic) thyroid gland. Congenital hypothyroidism may also be due to dyshormonogenesis, caused by a complete or partial defect in thyroid hormone synthesis. Rarer causes of congenital hypothyroidism are defects in how thyroid hormone impacts target tissues. This may be due to abnormalities in cell membrane transport, metabolism or action, and control of thyroid gland activity due to defects at the level of the hypothalamus or pituitary (central hypothyroidism) and more commonly the thyrotropin receptor.
Congenital hypothyroidism also occurs in some syndromic genetic disorders, for example, Kabuki syndrome, Johanson-Blizzard syndrome, and Pendred syndrome. Congenital hypothyroidism may be transient or permanent. A genetic diagnosis can aid in determining whether lifelong thyroid hormone replacement is necessary, as well as provide risk information and the possibility of genetic counseling to families.
The Hypothyroidism Panel includes sequence and deletion/duplication analysis of the listed genes.
