RET codon 618 mutations in Saudi families with multiple endocrine neoplasia Type 2A and familial medullary thyroid carcinoma

BACKGROUND AND OBJECTIVES: Certain diseases such as multiple endocrine neoplasia (MEN) 2A, MEN 2B, familial and sporadic medullary thyroid carcinoma (MTC) and renal dysgenesis are related to abnormalities of the RET protein. Our aim was to evaluate the frequency of RET mutation in 10 Saudi families with MEN type 2A and familial MTC. DESIGN AND SETTING: A cross-sectional prospective study of patients followed up at King Abdulaziz University Hospital and King Abdulaziz Medical City, Jeddah, between March 2001 and March 2011. PATIENTS AND METHODS: Genomic DNA was isolated from peripheral blood leukocytes of all subjects by standard procedures. Exons 10, 11, 13, 14 and 16 of the RET proto-oncogene were analyzed by single-strand conformation polymorphism, direct DNA sequencing and/or restriction enzyme analysis. RESULTS: We screened 79 subjects for the RET mutation. Of which 43 subjects had hereditary MTC were enrolled in this study. MEN type 2A was identified in 25 subjects; MTC was diagnosed in all 25 subjects (100%), pheochromocytoma in 13 subjects (52%) and hyperparathyroidism in 4 subjects (16%). The most frequent genotype in patients with MEN 2A syndrome was a codon 618 mutation (46.6%), followed by a codon 634 mutation (44.2%). Among the 5 families with MEN 2A, 3 had a mutation at codon 634, whereas 2 had a mutation at codon 618. CONCLUSION: The most frequent RET proto-oncogene mutation in our series was in codon 618 (exon 10).