Congenital hypothyroidism due to thyroglobulin deficiency: a case report with a novel mutation in TG gene

Congenital hypothyroidism (CH) is the most common endocrine disorder in neonates and infants with an incidence of one in 2,000 to one in 4,000 newborns. Primary CH can be caused by thyroid dysgenesis and thyroid dyshormonogenesis. CH due to a TG gene mutation is one cause of thyroid dyshormonogenesis and can be characterized by goitrous CH with absent or low levels of serum thyroglobulin (Tg). In the present case, a 15-day-old neonate was referred to us with elevated thyroid stimulating hormone detected during a neonatal screening test. At the age of 34 months, extensive genetic testing was performed, including targeted exome sequencing for hypothyroidism, and revealed compound heterozygous mutations in the TG gene. Sanger sequencing of both parents' DNA samples revealed a c.3790T> C (p.Cys1264Arg) mutation located at exon 17 inherited from the mother, and a c.4057C> T (p.Gln1353*) mutation located at exon 19 was inherited from the father. The c.4057C> T (p.Gln1353*) mutation located at exon 19 has never been reported and, therefore, is a new discovery. We report a case of primary permanent CH with compound heterozygous mutations of the TG gene, including a novel mutation.