Presence of the RET Cys634Tyr mutation and Gly691Ser functional polymorphism in Iranian families with multiple endocrine neoplasia type 2A.

PURPOSE Multiple Endocrine Neoplasia type 2A (MEN2A) is a complex autosomal dominant inherited syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and primary parathyroid hyperplasia. In patients with only one or two clinical features, identification of a germ line RET (REarranged in Transfection) mutation is required to make the diagnosis and initiate genetic counseling. METHODS We analyzed blood DNA from three Iranian families with three generations of MEN2A including 20 affected individuals with MTC and four with pheochromocytoma. RET hotspots were amplified in probands and sequenced for mutation detection. RESULT The causative mutation in all families was found to be the Cys634Tyr missense substitution. The presence of a functional SNP resulting in Gly691Ser was also detected in exon 11 of 15 affected cases. Four patients showed both of these RET variations. CONCLUSION Our study shows that the Cys634Tyr missense substitution and the Gly691Ser polymorphism are recurrent in Iranian patients, since our families are unrelated. All asymptomatic carriers of the Cys634Tyr high-risk activating mutation were referred for prophylactic thyroidectomy.