Defective SLC5A5 causes thyroid dyshormonogenesis 1 (TDH1)

Human SLC5A5 encodes the Na+/I- symporter NIS which is localised in the basolateral membrane of thyrocytes facing the bloodstream where it mediates iodide accumulation into these cells. Defects in SLC5A5 can cause hyroid dyshormonogenesis 1 (TDH1; MIM:274400), a disorder characterised by the inability of the thyroid to maintain a concentration difference of readily exchangeable iodine between the plasma and the thyroid gland (termed iodine trapping) leading to congenital hypothyroidism.

Summary from Reactome (R-HSA-5619096), read 2026-09-23.