Search

Background: Congenital hypothyroidism (CH) due to the thyroid dyshormonogenesis is more prevalent in Iran in comparison to other countries. Sodium iodide symporter (NIS) is one of the plasma membrane glycoproteins that is located on the basolateral side of thyroid follicular cells and mediates active I− trapping into these cells. Playing a prominent role in thyroid hormone synthesis, NIS gene mutations can be a cause of permanent CH with the etiology of dyshormonogenesis. The aim of this study was to investigate the occurrence of T354P mutation of the NIS gene, in a group of children affected with permanent CH in Isfahan. Materials and Methods: Thirty-five patients with the etiology of dyshormonogenesis, and 35 healthy children, collected between 2002 and 2011 in Isfahan Endocrine and Metabolism Research Center, were examined for T354P mutation of the NIS gene by direct polymerase chain reaction-sequencing method. Results: No T354P mutation was detected in any of the studied children. Conclusions: More subjects with confirmed iodide transport defects should be screened for detecting the frequency of different reported NIS gene mutations in our population.

Background: Considering the higher prevalence of congenital hypothyroidism (CH) in Iran and the importance of determination of the etiology of CH for assessing appropriate treatment strategies, understanding the pathogenesis of CH and the implications of its inheritance and prognosis, the aim of this study was to determine the etiology of CH 7 years after initiation of the program in Isfahan province. Materials and Methods: In this cross-sectional study, children with a primary diagnosis of CH studied. They clinically examined and their medical files were reviewed by a Pediatric Endocrinologist. Considering screening and follow-up lab data and radiologic findings the etiology of CH was determined. Screening properties of different etiologies of CH was compared. Results: In this study, 437 patients with permanent CH (PCH) were studied. Etiology of PCH in 316 (72.3%) and 121 (27.7%) of cases was thyroid dyshormonogenesis and thyroid dysgenesis, respectively. Prevalence of agenesis, ectopia, hypoplasia and hemiagenesis in thyroid dysgenetic patients was 13.3%, 6.4%, 4.3% and 3.7% respectively. Mean of thyroid stimulating hormone in screening, recall and after discontinuing treatment at 3 years of age was significantly lower in dyshormonogenetic CH patients than dysgenetic ones(P < 0.01). Conclusion: Seven years of our experiences in CH screening program indicated that the etiology of CH in Isfahan, with a higher rate of CH, with a predominance of thyroid dyshormonogenesis is different from most of the studies world-wide and similar to other reports from Iran. The findings of the current study provide us baseline information for determination of CH pathogenesis in this region.

Background: Despite elimination of iodine deficiency, the rates of both permanent and transient congenital hypothyroidism (CH) in our study were higher than the comparable worldwide rates, which emphasize the major role of genetic factors in the pathogenesis of CH and many studies in this regard confirm this possibility. Materials and Methods: In this review, we report all studies that established during CH screening program regarding familial and genetic component of the disease. Results: Although we could not entirely ignore the possible role of environmental and autoimmune factors in the development and function of thyroid gland, our findings strongly suggest the role of genetic factors as dominant etiologic factor in CH. Conclusion: The studies support the existence of a familial component of CH involving dominant genetic predisposition factors with a low penetrance. Considering the polygenic/multifactorial basis of CH, they suggest the possible involvement of other unknown genes in the pathogenesis of the disease, which may also follow non-Mendelian pattern of inheritance.