Absence of mutations in the MEN2A region of the ret proto‐oncogene in non‐MEN 2A phaeochromocytomas

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Abstract
Summary: OBJECTIVE To determine the presence of abnormalities of the MENZA region of the ret proto‐oncogene in phaeochromocytomas/paragangllomas (PHAEO) of different aetiologies.DESIGN Total RNA was extracted from tumours and used as templates for reverse transcriptase polymerase chain reactions. A ret primer pair, which encompasses the region which is mutated in the germ‐line of patients with MEN 2A, was used. The resulting 262‐bp product was sequenced.PATIENTS Ten PHAEOs were examined. Four tumours were from von Hippel‐Lindau disease patients; five were sporadic, Isolated tumours; one from a patient with multiple endocrine neoplasia type 2A (MEN 2A). The medullary thyroid cancer from the single MEN 2A patient was also examined.RESULTS A heterozygous TGC to CGC mutation of codon 634 (cysteine to arginine) was found In the PHAEO and medullary thyroid cancer from the MEN 2A patient. The 262‐bp ret fragment was not found in two tumours (one malignant PHAEO and one secretory paraganglloma), although the Intra‐cellular ret tyrosine kinaw domain was detected in these tumours. The cysteine codons were normal in all other non‐MEN 2A PHAEOs.CONCLUSION Mutations of key cysteine codons of the ret proto‐oncogene may be specific to MEN 2A.