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Molecular Genetics Laboratory

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Multiple Endocrine Neoplasia 2B, MEN2B (RET Sequence Analysis, Exon 16)

  • Synonyms: MEN Type IIB, Mucosal Neuroma Syndrome
  • LIS Mnemonic: MBMEN2B

    Collect

    Collect whole blood in a purple top (EDTA) tube (preferred). Extracted DNA is also acceptable.

    Volume Required

    5 ml whole blood or 1 ug extracted DNA.

    Minimum Required

    3 ml whole blood

    Transport

    Refrigerate sample until shipment. Send the sample at room temperature with overnight delivery for receipt Monday through Friday within 24 hours of collection.

    Stability

    Whole blood can be refrigerated until shipment.

    Unacceptable conditions

    Heparinized specimens, severely hemolyzed specimens, frozen, clotted or possibly commingled specimens, blood in non-sterile or leaky containers, mislabeled or inappropriately labeled specimens.

    Specimen Handling

    Do not heat, freeze or centrifuge blood before shipment. Refrigerate sample until shipment.

Days Performed

Mon - Fri 9:00am to 4:00pm

Reported

2-3 weeks

CPT

81404

Disease Information

Clinical Features:

Multiple Endocrine Neoplasia type 2 (MEN 2) is an autosomal dominantly inherited cancer disorder classified in to three subtypes: MEN 2A, MEN 2B and familial medullary thyroid carcinoma (FMTC). All three subtypes carry a high risk for development of medullary carcinoma of the thyroid (MTC). The onset of MTC is in early childhood in MEN 2B and early adulthood in MEN 2A. MEN2A is characterized by medullary thyroid carcinoma, pheochromocytoma, and parathyroid hyperplasia. MEN2B is characterized by bilateral medullary thyroid carcinoma, pheochromocytoma, diffuse ganglioneuromas of the intestinal tract, mucosal neuromas, and skeletal abnormalities. Symptoms of MEN2B are evident within the first decade of life and progresses rapidly.

Molecular Genetics:

Approximately 95% of individuals with the MEN 2B phenotype have a single point mutation in the tyrosine kinase of the RET proto-oncogene at codon 918 in exon 16.

Test Methods:

We offer DNA sequence analysis of exon 16 of the RET proto-oncogene. The patient’s gene sequence is then compared to a reference sequence. Sequence variants are classified as mutations, variants of unknown significance or benign variants unrelated to disease. Variants of unknown significance may warrant further studies in the patient and other family members. Mutations in other exons, promoters, deep intronic regions and other regulatory regions will not be identified with this assay.

Detection Rate:

In greater than 95% of MEN2B cases, there is a mutation at a single position within the extracellular ligand-binding domain of the RET proto-oncogene. The analytical sensitivity for sequencing is close to 100%.

Results:

Test results with interpretation will be mailed and/or faxed to the referring physician following completion of the test. Additional reports will be provided as requested.

Utility:

The clinical utility of this assay is in confirming a clinical diagnosis of MEN 2B, to facilitate pre-symptomatic testing of at risk relatives, confirm the need for clinical surveillance or surgery in patients positive for a mutation, and to facilitate prenatal diagnosis.

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215-590-5221