We report four children originating from two unrelated German families with congenital hypothyroidism (CH) due to mutations in the thyroid peroxidase (TPO) gene. Three female siblings (family 1) were found to be compound heterozygous for two mutations, a known mutation in exon 9 (W527C), and a mutation in exon 8 (Q446H), which has not been described before. In the second family we identified a boy with goitrous CH, who had a novel homozygous mutation in the TPO gene in exon 16 (W873X). All children of family 1 were diagnosed postnatally by newborn screening. The case of the boy of family 2 has already been reported for the in utero treatment of a goiter with hypothyroidism.
Conclusion: Our results confirm existing data on the phenotypic variability of patients with TPO gene mutations.