Congenital hypothyroidism caused by a novel mutation of the dual oxidase 2 (DUOX2) gene

The dual oxidase 2 (DUOX2) mutation results in an impairment of the hydrogen peroxidase-generating system and is identified as a dyshormonogenic cause of congenital hypothyroidism (CH). Here, we describe two unrelated Japanese girls with CH due to a novel DUOX2 mutation. They had high serum thyrotropin levels and low free thyroxine/thyroxine concentrations during the neonatal period. A novel missense mutation with a transversion of G to A at position 1462 in exon 12 of the DUOX2 gene that caused a replacement of glycine (G) with arginine (R) at codon 488 of the protein (c.1462G >A, p.[G488R]) was identified. One patient was a compound heterozygote for p.[L479SfsX3]+[G488R]. The other was homozygous for p.[G488R]. This p.G488R substitution occurred in a highly conserved glycine residue of the mammalian DUOX2 protein. The two patients had different haplotypes, suggesting that the p.G488R alleles were the result of independent, recurrent mutations. Later in life, both patients were still euthyroid even after discontinuing thyroid hormone therapy. We conclude that this p.G488R missense mutation in the DUOX2 gene of the patients is associated with thyroid dysfunction that presents during the neonatal period.