Insertion of an Alu Element in Thyroglobulin Gene As a Novel Cause of Congenital Hypothyroidism

The thyroglobulin (TG) gene encodes a protein required for thyroid hormone synthesis and iodine storage. Deleterious TG mutations produce congenital hypothyroidism (CH) often presenting with undetectable serum TG. Alu elements, common throughout the human genome, have a poly(dA) region in the 3' end of the strand. Herein two of four siblings of a consanguineous Sudanese family with CH, goiter, high initial serum thyrotropin, and undetectable TG were found to have a novel frameshift insertion of an Alu element within an exon of the TG gene: c.7909ins p.Y3637Ffs. This report demonstrates a novel Alu element insertion within TG causing CH.