Mild and severe congenital primary hypothyroidism in two patients by thyrotropin receptor (TSHR) gene mutation

Congenital hypothyroidism (CH) is the most commonly encountered endocrinological birth defect, with an incidence of approximately 1 in 3000-4000 live births. It could be sporadic or familial as well as goitrous or non-goitrous. Inactivating mutations of TSHR , which is one of the genes responsible for non-goitrogenic congenital hypothyroidism, are mostly inherited autosomal recessively and result in a wide clinical spectrum owing to the extent of receptor function loss. Here, we report detailed clinical features of two CH cases with TSHR mutations. The first case was diagnosed before the initiation of the national screening program and had a severe clinical phenotype associated with a homozygous inactivating TSHR mutation (P556R), whereas the second case was diagnosed after the introduction of the national screening program and showed a mild clinical presentation and carried another homozygous missense mutation (P162A) in the TSHR gene. We compared the clinical features of our cases with those of previously reported patients with TSHR mutations to enhance the genotype/phenotype correlations between these mutations and corresponding clinical phenotypes.