ESPE Abstracts

Background: Mexico is globally ranked as one of the countries with the highest incidence of congenital hypothyroidism. There are few studies that have searched for germinal mutations of candidate genes, such as NKX2-1, in patients with congenital hypothyroidism.

Objective and hypotheses: i) To search for NKX2-1 mutations in blood samples of patients with confirmatory diagnosis of congenital hypothyroidism (CH) due to thyroid dysgenesis (TD). ii) To describe their clinical findings and to identify cases of minimal gene expression or no penetrance by the clinical and molecular study of first degree relatives of patients with an identified NKX2-1 mutation. Hypothesis: NKX2-1 mutations may cause CH due to TD in Mexican population.

Method: This study has an observational, descriptive, transversal and ambispective design. We included 34 Mexican patients in which NKX2-1 mutations were searched by PCT, single-strand conformation polymorphism (SSCP) and Sanger automated sequencing of the three coding exons.

Results: In the 34 patients included there was a female gender predominance (3.8:1). Most of our patients had ectopic thyroid (n=19). We found an abnormal migration pattern in exon 1 by SSCP in five of our patients, but we discharged any mutation by exon sequencing. In all of our patients the analysed sequence of NKX2-1 gene was normal, no mutations or polymorphisms were found.

Conclusion: In this study the high predominance of CH in Mexican population is not explained by mutations or polymorphisms in NKX2-1 gene, so further studies are needed to analyse other genes involved in thyroid development, such as NKX2-5 and FOXE-1 to determine their role as a cause or influencing factor of CH due to TD in our population.