The strong association of CDKN1A SNP with reduced MTC risk was further confirmed on multivariate logistic regression analysis in both the hereditary (OR = 0.27; 95% CI = 0.13‐0.55; P < .001) and sporadic MTC groups (OR = 0.53; 95% CI = 0.36‐0.78; P = .001) (Table 2 and 4). Here, CDKN1A is linked to medullary thyroid gland carcinoma.