Athyreosis, dysgenesis, and dyshormonogenesis in congenital hypothyroidism

Congenital hypothyroidism (CH) is most commonly caused by defects in thyroid development leading to thyroid dysgenesis (80-90%), which consists of thyroid agenesis, ectopy or hypoplasia. Thyroid dysgenesis occurs mostly as a sporadic disease. However, a small but significant proportion of the cases are due to defects in transcription factors. The remaining 10-20% of congenital hypothyroidism is due to better-defined defects in any of the steps in the thyroid hormone biosynthesis, collectively called thyroid dyshormonogenesis, which are inherited autosomal recessively. Studying multiplex and/or consanguineous families with carefully defined, original phenotypes by such recently popular techniques as genome wide SNP genotyping with linkage search is likely to reveal novel disease associated genes. Thus there is new insight into the pathophysiology of congenital hypothyroidism.