What should be the focus of genetic testing for MEN 2A and 2B in the diagnosis of pheochromocytoma?

Updated: Aug 10, 2018
  • Author: Michael A Blake, MBBCh, MRCPI, FRCR; Chief Editor: George T Griffing, MD  more...
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Answer

Particular attention is given to specific sequences for the codons known to be hot spots for mutations causing the MEN 2A and 2B syndromes. Over 95% of cases of MEN 2A and 85% of cases of familial medullary thyroid cancer are associated with mutations affecting 1 of 5 codons located in exons 10 (codon 609, 611, 618, and 620) and 11 (codon 634). Over 95% of individuals with MEN 2B have a germline mutation in codon 918 of exon 16.

In patients with MEN 2A, also obtain a serum intact parathyroid hormone level and a simultaneous serum calcium level to rule out primary hyperparathyroidism (which occurs in MEN 2A). Obtain a serum calcitonin level as well. Some investigators advocate a pentagastrin infusion test; however, genetic screening tests for the ret proto-oncogene may eliminate the need for this provocative test.

In patients with VHL disease, obtain a consultation with an ophthalmologist to rule out retinal angiomas, and consider brain MRI to exclude cerebellar hemangioblastomas. Obtain a CT scan of the kidneys and pancreas to rule out cysts.


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