Genetic Contributors to Hashimoto’s Thyroiditis
Genes account for 70% of the risk of developing autoimmune thyroiditis, while the environment accounts for the remaining 30% . Hashimoto’s thyroiditis is the most common form of autoimmune thyroiditis and the most common cause of hypothyroidism in the United States .
If you have a sibling with Hashimoto’s, you have twice the risk of developing the disease compared to healthy people. If one of your parents has Hashimoto’s, then you may have triple the risk of developing the disease .
Genes that are commonly found in Hashimoto’s patients include:
1) ZFAT (cell survival gene) is a gene that prevents cell death (apoptosis).
Reduced production of ZFAT has been associated with cell death in connective tissue and problems with cell development .
Having a T variant for Ex9b-SNP10 at intron 9 is associated with increased rates of autoimmune thyroiditis .
2) PDE8B is a gene that functions primarily in the thyroid.
A SNP (rs4704397) of PDE8B has been associated with hypothyroidism. PDE8B gene mutations may lead to higher TSH levels .
3) PTPN22 encodes a protein that prevents the activation of immune cells called T-cells (involved in H inhibitor of T-cell activation
4) The Thyroglobulin (Tg) gene is involved in the synthesis of thyroid hormones T4 and T3.
SNPs of the Tg gene at exon-33 may predispose people to autoimmune thyroid diseases, although the exact mechanisms are unknown. The D8S272 marker is indirectly linked to susceptibility to autoimmune thyroid diseases .
The 1623 A/G SNP of the Tg gene promoter (rs180195) is positively associated with Hashimoto’s thyroiditis. Individuals with Hashimoto’s are more likely to have the A/G variants .
5) The Vitamin D receptor gene (the “sunshine gene”) is critical for Vitamin D absorption.
Mutations in the vitamin D receptor gene can cause vitamin D deficiency (<30 ng/mL) .
Vitamin D deficiency is positively correlated with increased thyroid antibodies, a common feature of autoimmune thyroid diseases .