Thyroid Dysfunction and Oral Lichen Planus: Evidence From Two-Sample Mendelian Randomization Analysis

Area of Science:

• Genetics
• Immunology
• Endocrinology

Background:

• The association between thyroid dysfunction (TD) and oral lichen planus (OLP) is controversial and lacks clear causal understanding.
• Previous epidemiological studies have yielded conflicting results regarding the link between TD and OLP.

Purpose of the Study:

• To investigate the probable mutual causality between thyroid dysfunction and oral lichen planus using bidirectional Mendelian randomization (MR) analyses.
• To establish a genetic basis for the relationship between TD and OLP for improved clinical applications.

Main Methods:

• Utilized genome-wide association studies data for genetic instruments of OLP and 10 TD phenotypes.
• Employed the inverse variance weighted method for bidirectional causal assessment, with sensitivity analyses for robustness.
• Applied Bonferroni correction for significance testing.

Main Results:

• Forward MR indicated Hashimoto's thyroiditis and hypothyroidism are linked to increased OLP risk.
• Reverse MR suggested OLP is related to hyperthyroidism and thyroid cancer.
• OLP significantly increased the risk of Hashimoto's thyroiditis, Graves' disease, hypothyroidism, and elevated TSH levels.

Conclusions:

• Hypothyroidism is a significant risk factor for OLP.
• OLP may contribute to the development of autoimmune thyroid disorders, including Hashimoto's thyroiditis and Graves' disease.
• Findings highlight complex endocrine-immune interactions, suggesting shared pathways and clinical implications for early screening and treatment.