Approximately 15%–20% of all cases occur in a hereditary, familial context and include high to moderate penetrant genes also reported as a genetic risk factor for other cancers: breast cancer gene 1 (BRCA1), BRCA2, ataxia telangiectasia mutated (ATM), checkpoint kinase 2 (CHEK2), partner and localizer of BRCA2 (PALB2), mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), MSH6, PMS2. BRCA1 and BRCA2 genes are mainly discussed for hereditary breast and ovarian cancers, although there is a higher risk for other malignancies like colon cancer, melanoma, thyroid cancer, and prostate cancer [7]. The gene discussed is MLH1; the disease is thyroid cancer.