ESPE Abstracts

Thyroid dysgenesis (TD) is the most common cause of congenital hypothyroidism in iodine sufficient regions. TD includes a broad spectrum of developmental anomalies varying from absence of thyroid (athyreosis) to an abnormally located thyroid (ectopy), small (hypoplasia) or asymmetric thyroid. Thyroid dysgenesis is usually sporadic, but up to 2% of cases is familial. Genetics of TD is complex and advances in developmental biology over the past two decades revealed monogenetic forms of TD. But these monogenetic forms represent less than 10% in TD and to date the discordance between monozygotic twins remains unexplained. However, inheritance of TD is not based on a simple Mendelian pattern and additional genetic elements might contribute to the wide spectrum of observed phenotypes. Accumulating evidence supports the view that the genetics is complex, possibly on a polygenic/multifactorial or epigenetic basis. Developmental biology allowed the identification of candidate genes (thyroid transcription factors) and broadened the spectrum of associated malformations in Humans. Detailed phenotype of patients, up-to-date technologies (high-throughput sequencing), and relevant animal models are crucial to advance our knowledge of the mechanisms in normal and abnormal thyroid development. We will provide an update on known responsible genes, new genes discovered in our laboratory and underlying mechanisms of TD. Up-to-date technologies in genetics and biology will allow us to advance in our knowledge and elucidate the enigma of TD. Our work on TD is partly financed, by the Fondation Jérôme Lejeune for the study of thyroid dysgenesis of Down syndrome in murine models, by Merck Serono France, Sandoz SAS France, Electricité de France, Princess Grace de Monaco Foundation, by Fondation Maladies Rares and by a national clinical research grant “PHRC”: ClinicalTrials.gov Identifier: NCT01916018.