Gene SLCA5
Back to Curriculum
Also known as
SLC5A5, Sodium/Iodide Symporter, NIS, Thyroid Iodide TransporterOverview
SLCA5, typically referring to the SLC5 family of sodium-dependent transporters, includes important proteins involved in nutrient absorption and cellular metabolism. The most clinically significant member is SLC5A5, which encodes the sodium/iodide symporter (NIS) responsible for iodide uptake in the thyroid gland, as well as other tissues. This transporter is essential for thyroid hormone synthesis, as it mediates the first step of iodide concentration from the bloodstream into thyroid follicular cells. The protein uses the sodium gradient across the cell membrane to drive iodide transport against its concentration gradient, achieving iodide concentrations 20-40 times higher than plasma levels.Mutations in SLC5A5 cause congenital hypothyroidism due to iodide transport defect (ITD), an autosomal recessive disorder characterized by the inability to concentrate iodide in the thyroid gland. Affected individuals typically present in infancy with hypothyroidism and goiter, and without treatment, can develop intellectual disability and growth retardation. Genetic variants in SLC5A5 also have implications for radioiodine therapy in thyroid cancer, as NIS expression determines the effectiveness of radioactive iodine uptake in thyroid tissue. Understanding SLC5A5 genetics is important for personalized approaches to both congenital hypothyroidism management and thyroid cancer treatment strategies.