RET and medullary thyroid gland carcinoma: Of 77 participants with medullary thyroid cancer in Geisinger MyCode, 28 (36.4%) were yet uninformed of their RET mutation status as part of the MyCode Genome Screening and Counseling Program, and none of them developed medullary thyroid cancer over 538 person-years of follow-up (median, 7.0 [IQR, 4.4-8.9] years) at a median age of 74.5 years (IQR, 58.1-84.3 years).