Fetal goitrous hypothyroidism and polyhydramnios in a patient with compound heterozygous DUOXA2 Mutations

Background: Fetal goiter is only rarely observed in pregnant women without autoimmune thyroid disorders, and there is no epidemiological data on its pathophysiology. Dual oxidase maturation factor 2 (DUOXA2), together with dual oxidase 2, serves pivotal roles in thyroid hormone biosynthesis. To date, all reported patients with DUOXA2 mutations were diagnosed postnatally through newborn screening for congenital hypothyroidism. Case Report: The mother of a male fetus presented at 33 + 4 gestational weeks (GW) with a fetal goiter and polyhydramnios. Cordocentesis revealed fetal hypothyroidism (TSH 253.4 mU/L, FT₄ 0.29 ng/dL). Intra-amniotic levothyroxine injections were performed at GW 34 + 3 and 35 + 3. The patient was born after spontaneous vaginal delivery at 35 + 6 GW without obstetrical complications. He was treated with levothyroxine until the age of 6 years when reevaluation of his thyroid functions showed normal results (TSH 1.32 mU/L, FT₄ 1.81 ng/dL). Eleven causative genes of CH, including DUOXA2, were analyzed with use of a next-generation sequencing technique. Results: A next-generation sequencing-based mutation screen led us to find that he was compound heterozygous for 2 previously reported nonsense DUOXA2 mutations (p.[Tyr138∗];[Tyr246∗]). Conclusion: The present case not only illustrates the phenotypic diversity of DUOXA2 mutation carriers but also implies that DUOXA2 is important in prenatal thyroid hormone production.