Our study aims to address this knowledge gap using Mendelian Randomization (MR) [13, 14], a method that leverages genetic variants as instruments to infer causal relationships between modifiable exposures and health outcomes, in this case, the association between cathepsin levels and the risk of developing papillary thyroid carcinoma (PTC), as well as the reverse of it. The gene discussed is CTSS; the disease is thyroid gland papillary carcinoma.