Absence of mutations at codon 768 of the RET proto-oncogene in sporadic and hereditary pheochromocytomas

Abstract

Sixteen sporadic pheochromocytomas, 3 pheochromocytomas in neurofibromatosis 1, and 4 pheochromocytomas in multiple endocrine neoplasia (MEN) 2A or 2B were screened for mutations at codon 768 of the RET proto- oncogene by Alu1 digestion of polymerase chain reaction (PCR) products and mutations in exon 13 by PCR-single strand conformation polymorphism (SSCP) analysis. Although mutations at codon 768 (GAG → GAC; Glu → Asp) of the RET proto-oncogene were recently reported to be found in 40% of sporadic medullary thyroid carcinomas (MTCs), the absence of missense mutations at codon 768 was confirmed both with PCR-restriction fragment length polymorphism (RFLP) and PCR-SSCP analysis in all examined cases of pheochromocytomas. These results suggest that mutations at codon 768 of the RET proto-oncogene do not represent a frequent mechanism of tumorigenesis for both sporadic and hereditary pheochromocytomas.