Screening Of DUOXA2 Gene Mutation In Children With Congenital Hypothyroidism With Goiter And Its Pathogenesis

Objective: The aim of this research was to identify the types and characterstics of DUOXA2 mutations associated with the genotype–phenotype relationship in congenital hypothyroidism(CH) with goiter patients from Shandong Province, China. We explored the effects of the novel DUOXA2 mutation(p.I26M) on DUOXA2 function, in order to study the pathogenesis of CH with goiter caused by DUOXA2 mutation.Methods: We enrolled 75 patients of CH with goiter in Shandong Province, China,and extracted Genomic DNA. All exons of DUOXA2 gene were amplified by PCR and the products were directly sequenced to find new mutations types of DUOXA2 gene,Blood samples were collected from 67 patients with CH and goiter. Furthermore, in order to explore the effects of the novel DUOXA2 mutation(p.I26M) on DUOXA2 function,we constructed the expression vector of wild-type and mutative-type of DUOXA2 gene,as well as the wild-type of DUOX2 gene. DUOXA2 and DUOX2 protein expression levels were detected by western blotting, and NADPH oxidase activity determined by measuring H2O2 generation in He La cells.Results: Sequencing of all six DUOXA2 exons in 75 cases with CH and goiter identified a novel heterozygous missense mutation, c.C78G(p.I26M), and a homozygoμs nonsense mutation, c.C738G(p.Y246X), in CH patients with mild transient and mild permanent goiter, respectively. Western blotting experiments showed that mutant I26 M protein expression levels did not differ from wild-type DUOXA2. H2O2 prodμction assay indicated that the novel DUOXA2 mutation(p.I26M) displayed a complete deficiency phenotype in generating H2O2.Conclusions: We identified a novel DUOXA2 mutation(p.I26M) causing CH with goiter, which affected H2O2 generation but did not alter protein expression levels, further confirming the essential role of DUOXA2 in thyroid hormone synthesis.