Does the RET variant G691S influence the features of sporadic medullary thyroid carcinoma?

Summary Objective The RET (rearranged during transfection) proto‐oncogene G691S variant is over‐represented in the germline of patients with sporadic medullary thyroid carcinoma (sMTC) vs. normal controls but so far is not associated with any medical or pathological features of the tumour. The aim of our study was to assess the influence of this variant on the age of onset, clinical, biological and pathological features of sMTC. Design and patients One hundred patients with histologically proven MTC, for whom the germline genetic analysis of RET was negative and medical records were available, were included in the study. Results Patients with the heterozygous GS variant or the homozygous SS variant (n = 36) were on average 8·0 years younger than patients with the wild‐type GG variant (n = 64, mean age 43·9 vs. 51·9 years, P 1000 pg/ml) was 2·75‐fold higher in the patients with the GS or SS variant than in those with the wild‐type variant (P