TG

The TG gene provides instructions for making a protein called thyroglobulin, one of the largest proteins in the body. This protein is found only in the thyroid gland, a butterfly-shaped tissue in the lower neck. Thyroglobulin combines with iodine and is modified and broken down to release small molecules known as thyroid hormones. Thyroid hormones play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism). Thyroglobulin also serves as a protein storehouse for iodine and inactive thyroid hormone until these substances are needed.

congenital hypothyroidism - caused by mutations in the TG gene

Several TG mutations have been identified in people with a mild to severe thyroid hormone deficiency. When the deficiency is severe enough during fetal development, it can cause congenital hypothyroidism. The mutations either delete a small segment of the TG gene or change one of the DNA building blocks (base pairs). As a result, the 3-dimensional shape of thyroglobulin is altered, reducing the amount of properly structured protein that is available for thyroid hormone production. In most affected individuals, the thyroid gland is enlarged (goiter) in an attempt to compensate for reduced hormone production.

autoimmune disorders - associated with the TG gene

A major cause of thyroid disease is autoimmunity, in which the body's immune response turns against itself. The autoimmune response is triggered by a combination of genetic and environmental factors and involves the production of large Y-shaped proteins called antibodies or immunoglobulins. Instead of attacking foreign substances such as toxins or proteins from bacteria and viruses, antibodies sometimes inappropriately attack thyroid proteins. Antibodies that attack the body's own proteins are called autoantibodies. The presence of autoantibodies to thyroglobulin in an indication of autoimmune thyroid disease.

Hashimoto thyroiditis is a common type of autoimmune thyroid disease. Individuals with Hashimoto thyroiditis may have reduced thyroid activity (hypothyroidism) and an enlarged thyroid gland (goiter). Some people with this disorder have autoantibodies to thyroglobulin.

other disorders - caused by mutations in the TG gene

TG mutations have also been identified in some people who have a goiter but normal or near normal thyroglobulin levels. These mutations either delete part of the TG gene or change one of the DNA building blocks (base pairs). As a result, the 3-dimensional shape of thyroglobulin is altered, reducing the amount of properly structured protein that is available for thyroid hormone production. The thyroid gland enlarges to compensate for decreased levels of thyroglobulin.