Furthermore, we showed that the co-occurrence of Y791F with the strong RET C634Y mutation explains the aggressive MTC phenotypes observed in a large affected family that was initially reported as Y791F-only.
We tested on thyroid follicular cells the transforming activity of RET(C634S), RET(K603Q), another mutant identified in a kindred with both PTC and MTC, RET(C634R) a commonly isolated allele in MEN2A, RET(M918T) responsible for MEN2B and also identified in kindreds with both PTC and MTC, and RET/PTC1 the rearranged oncogene that characterizes bona fide PTC in patients without MTC.
Penetrance of inherited medullary thyroid carcinoma and genotype-phenotype correlation in a large multiple endocrine neoplasia type 2A family with C634Y RET mutation.
Family 1 showed a germline mutation (C634Y) in three individuals; a sister and a brother with symptomatic MTC; the former also presented with pheochromocytoma and hyperparathyroidism, and her son was a nine-year-old boy of previously unknown status.
A 6 base pair (bp) deletion causing the loss of a cysteine residue at codon 634 and a mutation causing substitution from cysteine to tyrosine at codon 634 were detected in 2 sporadic MTCs as somatic events.