How do you get congenital hypothyroidism?

Genetic & sporadic: Hi. Congenital hypothyroidism left untreated is disastrous for the patient (cretinism). In the US, we screen all neonates for hypothyroidism. The only patient with cretinism I've seen was born in Mexico, where they don't screen neonates; it was tragic. There are known genes that can cause congenital hypothyroidism either in the homozygous recessive state or heterozygous dominant state. Screen!!!