DISEASE INFORMATION
Multiple endocrine neoplasia type 2 (MEN2), also known as Sipple syndrome, is characterized by benign or malignant tumors of the endocrine system. The most common malignancy associated with MEN2 is medullary thyroid carcinoma (MTC). MEN2 is caused by mutations that result in the activation of the RET proto-oncogene and is inherited in an autosomal dominant manner. Tumors generally occur in the endocrine system, but may also occur in non-endocrine tissues. Depending on the tissues  involved, MEN2 can be further subdivided into three subtypes: MEN2A, MEN2B, and familial medullary thyroid carcinoma (FMTC).¹

MEN2A is characterized by MTC in 95% of cases, hyperparathyroidism  in up to 30% of cases, and unilateral or bilateral pheochromocytomas in up to 50% of cases.^1,2 Co-segregation of RET- related Hirschsprung’s disease and MEN2A has also been reported.³

MEN2B is the rarer but most aggressive of the MEN2 subtypes, causing up to 10% of MEN2 cases. Clinical manifestations consist of:  MTC (100%) and pheochromocytoma (50%). MEN2B can be differentiated from MEN2A by a lack of hyperparathyroidism. Individuals affected with MEN2B also exhibit a marfanoid habitus, bumpy lips and tongues as a result of neuromas,^1,2 as well as intestinal ganglioneuromas in children.⁴

FMTC is the mildest of the subtypes and comprises about 5%-35% of MEN2 cases. Individuals are only affected with medullary thyroid carcinoma and do not exhibit any of the other MEN2 findings.^1,2 However, papillary thyroid carcinoma has been reported in patients with mutations in three specific codons of the RET gene.⁵

TESTING BENEFITS & INDICATIONS
Genetic testing is an especially useful diagnostic tool to differentiate sporadic medullary thyroid carcinoma (MTC) cases from those affected with multiple endocrine neoplasia type 2 (MEN2). According to Brandi et al (2001), it is beneficial if an individual is identified to be a carrier of a RET mutation before they reach adulthood as there are screening and surgical interventions that help diminish their mortality rate. For example, individuals with an undiagnosed pheochromocytoma have a high risk of death due to untreated hypertension and there are clearly established guidelines for thyroidectomy depending on MEN2 subtype. It is recommended that even sporadic cases of MTC be tested for RET mutations to improve prognosis. For example, early thyroidectomy can lower mortality from MTC to less than 5%.⁶

TEST DESCRIPTION
The Ambry Sequence: Multiple Endocrine Neoplasia Type 2 (MEN2) begins with double-stranded automated sequencing in sense and antisense directions of exons 10, 11, and 13-16 of RET plus at least 20 bases into the 5’ and 3’ ends of the corresponding introns. If no mutation is detected, testing continues automatically with sequencing of the remaining exons plus at least 20 bases into the 5’ and 3’ ends of the corresponding introns.

MUTATION DETECTION RATE
Mutations in the RET gene account up to 98% of individuals affected with MEN2.⁷ The Ambry Sequence: MEN2 is capable of detecting >99% of described mutations in RET.

SPECIMEN REQUIREMENTS
Blood:Collect 3-5 cc from adult or 2 cc minimum from child into EDTA purple-top tube (first choice) or ACD yellow-top tube (second choice). Store at room temperature or refrigerate. Ship at room temperature.
Blood Spot: Call for availability.
Saliva:Collect 2 ml into Oragene™ DNA Self-Collection container. Store and ship at room temperature.
DNA:Send 20 µg in TE at 50-100 ng/µl. Store frozen and ship on ice or dry ice.
Prenatal: Prenatal testing is available. Please call an Ambry Genetic Counselor to discuss your case.

REFERENCES
¹ Eng C et al. JAMA.1996; 276(19): 1575-1579.
² Fraue F et al. Horm. 2009; 8(1): 23-23.
³ Moore SW et al. Pediatr Surg Int. 2008; 24:521-530.
⁴ Lora M et al. J Clin Endoclinol Metab. 2005; 90(7): 4383-4387.
⁵ Brauckhoff M et al. Thyroid. 2002; 12(7): 557-61.
⁶ Brandi ML et al. J Clin Endocrinol Metab. 2001; 86: 5658-5671.
⁷ Lodish MB et al. Expert Rev Anticancer Ther. 2009; 8(4): 625-632.

DISCLAIMER
This test was developed and its performance characteristics were determined by Ambry Genetics Corporation.  The laboratory is regulated under the Clinical Laboratory Improvement Amendments 2003 as qualified to perform nonwaived testing.  The Ambry Sequence: Multiple Endocrine Neoplasia Type 2 (MEN2) (MEN 2A, 2B and FMTC) analyzes the following types of mutations: nucleotide substitutions, small deletions, small insertions (including small repeat expansion), and small indels.  It is not intended to analyze the following types of mutations: gross deletions/duplications, gross rearrangements, deep intronic variations, and other unknown abnormalities.  The pattern of mutation types varies with the gene tested and the Ambry Test detects a high but variable percentage of known and unknown mutants of the classes stated.  A negative result from the analysis cannot rule out the possibility that the tested individual carries a rare unexamined mutation or mutation in the undetectable group. Approximately 95% of patients with MEN 2A have RET mutations in exons 10 and 11, 95% of MEN2B cases have mutations in exons 15 and 16, and 88% of FMTC patients carry mutations in exons 10, 11, 13 & 14. The Ambry Sequence: Multiple Endocrine Neoplasia Type 2 (MEN2) (MEN 2A, 2B and FMTC) is designed and validated to be capable of detecting >99% of described mutations in RET (considering less than 1%   to be the other types of mutations).  Multiple endocrine neoplasia type 2 (MEN2) is a complex clinical disorder, which in most cases is due to alterations in RET generally detected by the Ambry Sequence: Multiple Endocrine Neoplasia Type 2 (MEN2) (MEN 2A, 2B and FMTC) except as noted above.  Mutations in other genes or the regions not tested by the Ambry Sequence: Multiple Endocrine Neoplasia Type 2 (MEN2) (MEN 2A, 2B and FMTC) can also give rise to clinical conditions similar to Multiple Endocrine Neoplasia Type 2 (MEN2) (MEN 2A, 2B and FMTC). Although molecular tests are highly accurate, rare diagnostic errors may occur.  Possible diagnostic errors include sample mix-up, erroneous paternity identification, technical errors, clerical errors, and genotyping errors. Genotyping errors can result from trace contamination of PCR reactions, from maternal cell contamination in fetal samples, from rare genetic variants, which interfere with analysis, or from other sources. This report does not represent medical advice.  Any questions, suggestions, or concerns regarding interpretation of results should be forwarded to a genetic counselor, medical geneticist, or physician skilled in interpretation of the relevant medical literature.