| Thyroid peroxidase (TPO) plays an important role in the synthesis of thyroid hormone. Tassi et al., Catania, Italy, looked for TPO gene mutations in patients with CH due to impairment of thyroid hormone synthesis. They found dyshormogenesis in 10 out of 94 patients with CH. Seven of these cases were sporadic and 3 patients were from the same family. They found 4 mutations in 3 patients (one patient had 2 mutations) that were inherited from one of the parents. The authors conclude that TPO gene mutations play a major role in the pathogenesis of CH due to dyshormogenesis. A similar study but then related to mutations in the genes of PAX8 (that plays a role in organogenesis of the thyroid) and the TSH receptor (TSHR) in familial CH, was reported by Rydlewski et al., Brussels, Belgium, and Lyon, France. They studied two families and in one family they found a mutation in the gene of PAX8 and in the other family in the gene of TSHR. However, the authors conclude that these types of mutations are probably responsible for only a minority of cases with familial CH since sequencing of these genes in a series of sporadic cases did not reveal the presence of mutations. Park et al., Cambridge, Cardiff, and Southampton, UK, reported two pairs of siblings with CH due to mutations in the TSHR gene. Both pairs of siblings were compound heterozygote for two different TSHR gene mutations. |
