Molecular characterization of iodotyrosine dehalogenase deficiency in patients with hypothyroidism.

Context: The recent cloning of the human iodotyrosine deiodinase (IYD) gene enables the investigation of iodotyrosine dehalogenase deficiency, a form a primary hypothyroidism resulting from iodine wasting, at the molecular level.

Objective: In the current study, we identify the genetic basis of dehalogenase deficiency in a consanguineous family.

Results: Using HPLC tandem mass spectrometry, we developed a rapid, selective, and sensitive assay to detect 3-monoiodo-l-tyrosine and 3,5-diodo-l-tyrosine in urine and cell culture medium.