Absence of RET Proto-Oncogene Mutations in a Father and Son with Pheochromocytoma and Pancreatic Islet Cell Tumor

Background We describe a father and son with a combination of pheochromocytoma and pancreatic islet cell tumor. Although its familial occurrence is rare, this syndrome could be called overlapping‐type multiple endocrine neoplasia (MEN), since it fulfills the criteria for both type 1 and type 2 MEN. Recently, germ line mutations of the RET proto‐oncogene (RET) were found to be related to tumorigenesis and disease phenotypes in type 2 MEN. Methods Using polymerase chain reaction‐single strand conformation polymorphism (PCR‐SSCP) analysis, we looked for germ line mutations of RET in 8 members of this family, including the 2 patients. Results Analysis of RET exons 10, 11 and 16, which contain the hot‐spot codons for MEN type 2, revealed no mutations in any individual examined. Conclusion These findings suggest that these 3 exons in RET are not related to tumorigenesis in overlapping‐type MEN.