Thyroid Dyshormonogenesis 4 (IYD)
Thyroid dyshormonogenesis 4 is an autosomal recessive disorder caused by pathogenic variants in the gene IYD. This disorder is characterized by low thyroxine, a large multinodular goiter, low T4 levels, and excessive levels of iodotyrosine in serum and urine. Patients with this disorder may present with coarse facial features, macroglossia, large anterior fontanelles, myxedema, and umbilical hernia, and affected infants can also display decreased activity, poor feeding and weight gain, poor growth, hypotonia, a hoarse cry, and developmental delay. Life expectancy for this disorder is normal with early diagnosis and proper treatment.
For information about carrier frequency and residual risk, please see the residual risk table.