Genetics of Thyroid Function
Thyroid hormones regulate metabolism, energy production, cardiac function, and cognitive function. Genetic variants in thyroid hormone synthesis, receptor, and autoimmunity genes influence thyroid function and risk of hypothyroidism, hyperthyroidism, and thyroid autoimmune disease.
This page is for educational and informational purposes only. Not a diagnostic tool. Always consult a qualified healthcare provider.
What is Thyroid Function?
The thyroid gland produces thyroxine (T4) and triiodothyronine (T3) under TSH regulation from the pituitary. Thyroid function disorders are common, particularly in women: hypothyroidism (most often Hashimoto's thyroiditis, an autoimmune condition) and hyperthyroidism (most often Graves' disease). COVID-19 has been associated with new-onset thyroid dysfunction including subacute thyroiditis and Graves' disease. Genetic variants in TSHR (TSH receptor), TG (thyroglobulin), TPO (thyroid peroxidase), and immune genes including HLA-DR and PTPN22 influence thyroid disease susceptibility. Thyroid dysfunction can cause fatigue, weight changes, cognitive impairment, and autonomic symptoms — symptoms overlapping with Long COVID.
Biological pathways commonly discussed in relation to Thyroid Function
Research into Thyroid Function and Thyroid Disorder Genetics has highlighted several biological pathways that may be relevant. Genetic variants within these pathways may influence individual susceptibility, symptom severity, or the trajectory of the condition.
Thyroid Hormone Synthesis
Thyroglobulin (TG) is iodinated by thyroid peroxidase (TPO) on the follicular cell membrane, forming T4 and T3. Iodide is actively transported by NIS (SLC5A5). Variants in TPO and TG can cause congenital hypothyroidism. TPO antibodies (anti-TPO) are the primary marker of Hashimoto's thyroiditis.
Tsh Signalling
TSH (thyrotropin) binds TSHR (TSH receptor) on thyrocytes, activating adenylyl cyclase and stimulating thyroid hormone synthesis. Gain-of-function TSHR variants cause non-autoimmune hyperthyroidism. TSH-stimulating autoantibodies in Graves' disease mimic TSH, causing excessive thyroid hormone production.
Thyroid Autoimmunity
Hashimoto's thyroiditis is driven by CD8+ cytotoxic T cells destroying thyrocytes and TPO/TG autoantibodies. Graves' disease involves TSH receptor-stimulating antibodies. Both conditions involve HLA-DR3/DQ2 haplotypes, PTPN22 R620W, and CTLA4 variants affecting T cell regulation.
Thyroid Hormone Action
T3 binds nuclear thyroid hormone receptors (THRA, THRB) regulating metabolism, cardiac rate, thermogenesis, and cognitive function. DIO1/2 (deiodinases) convert T4 to active T3. DIO2 Thr92Ala variant affects T4-to-T3 conversion and may influence thyroid hormone sufficiency in tissues.
Key genes studied in relation to Thyroid Function
The following genes have been studied in relation to Thyroid Function and Thyroid Disorder Genetics. These genes span the biological pathways most commonly discussed in this area of research.
Genetic variants commonly discussed
The following genetic variants (SNPs) are found in genes that have been studied in relation to Thyroid Function. Each variant represents a position in the genome where individuals may carry different alleles.
14 variants total across genes studied in relation to Thyroid Function.
How personal DNA data may provide educational insights
Consumer DNA files from 23andMe, AncestryDNA, and MyHeritage contain raw SNP data. When you upload your file to ChronicDNA, the analysis engine checks your genotype against a curated panel of 80+ genes selected for their relevance to Long COVID, ME/CFS, and connected biological pathways - some of which may relate to areas such as Thyroid Function.
This is not a diagnostic service. Genetic variants do not determine whether you have Thyroid Function, nor do they predict your clinical outcomes. The report is educational - it explains which variants you carry, what the research says about them, and how they fit into the biological pathways most relevant to chronic illness. All results should be discussed with a qualified healthcare provider.
Related conditions and pathways
Thyroid Function shares biological pathways and genetic associations with the following related conditions and areas of research.
Frequently asked questions
Can COVID-19 cause thyroid problems?
Yes — COVID-19 has been associated with subacute thyroiditis (follicular inflammation causing transient hyperthyroidism then hypothyroidism), new-onset Graves' disease (hyperthyroidism), and Hashimoto's-like thyroid dysfunction post-infection. The mechanisms may include direct viral infection of thyroid cells expressing ACE2, immune activation, and molecular mimicry of thyroid antigens.
What is the DIO2 Thr92Ala variant?
DIO2 Thr92Ala (rs225014) affects type 2 deiodinase, which converts T4 to active T3 in peripheral tissues. The Ala allele reduces enzyme activity, potentially causing relative T3 deficiency in tissues even with normal serum thyroid function tests. Some studies suggest Ala/Ala carriers may respond better to combined T4/T3 therapy than T4 alone.
How do genetics cause hypothyroidism?
Hashimoto's thyroiditis — the most common cause of hypothyroidism in developed countries — has strong genetic components including HLA-DR3 and HLA-DQ2 haplotypes, PTPN22 R620W, CTLA4 variants, and susceptibility loci near TG and TPO. Congenital hypothyroidism can result from TPO or TG mutations disrupting thyroid hormone synthesis.
Which thyroid function genes are studied?
Key genes include TSHR, TPO, TG, SLC5A5 (NIS), DIO1, DIO2, THRA, THRB, and immune risk genes HLA-DR3, PTPN22, CTLA4. These cover thyroid hormone synthesis, TSH signalling, deiodinase conversion, and autoimmune susceptibility.
Explore DNA insights
If you already have DNA data from 23andMe, AncestryDNA, or MyHeritage, upload your raw file to ChronicDNA and receive a personalised educational report covering genes studied in relation to Thyroid Function and connected biological pathways.
Get Your Personalised DNA ReportInformational and educational only · Not a diagnostic tool · GDPR compliant
5 genes · 14 variants analysed in relation to Thyroid Function