Routine screening for germline RET mutations is recommended for all patients with medullary thyroid cancer

All patients with medullary thyroid cancer (MTC) are routinely screened for germline mutations in the rearranged during transfection (RET) proto-oncogene. In this Practice Point commentary, we discuss a cross-sectional study by Machens and Dralle, who performed germline RET proto-oncogene mutation analysis in patients with MTC at a tertiary referral centre in Germany to reveal patterns of familial disease presentation over the generations. The study identified a typical distribution of germline RET mutations (subclassified into three accepted risk categories) in the study population, consistent with the reported literature. The investigators also attempted to obtain data on the time of appearance of RET germline mutations in previous generations of the families. The natural history of MTC and penetrance of specific RET mutations could not be clearly identified in each family because of the cross-sectional nature of the study. Nevertheless, the study re-establishes the importance of routine screening for germline RET mutations in all new cases of MTC.