LabPLUS is part of Auckland District Health Board
and provides medical laboratory testing
| Services |
MOLECULAR GENETICS TESTS - MULTIPLE ENDOCRINE NEOPLASIA TYPE 2 |
| Background: Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant cancer syndrome which has classically been divided into two subtypes: MEN 2A and MEN 2B. Age of onset is variable but may range from childhood to the seventh decade. For MEN 2A, there is incomplete penetrance with only about two thirds of gene carries being symptomatic by age 70. Biochemical screening can increase the detection rate in these asymptomatic individuals. The characteristic features of MEN 2A include multifocal medullary thyroid carcinoma (MTC), bilateral phaeochromocytoma and primary hyperparathyroidism. MEN 2B is characterised by MTC, phaeochromocytoma, and multiple mucosal neuromas. Other features of MEN 2B include enlarged nerves of the gastrointestinal tract (ganglioneuromatosis), marfanoid habitus, hypotonia and corneal nerve thickening. In addition to MEN 2A and 2B, families have also been described with MTC alone, without phaeochromocytomas or primary hyperparathyroidism (familial MTC). For all three of these conditions, early diagnosis and appropriate surgical intervention can prevent metastatic MTC and can reduce the morbidity and mortality due to MTC. Previous presymptomatic diagnosis involved measurement of calcitonin with and without stimulation by calcium or pentagastrin to detect early signs of thyroid disease (c-cell hyperplasia). Genetic linkage studies have mapped the MEN 2A gene to the pericentromeric region of chromosome 10 where the RET proto-oncogene is located. Family studies in MEN 2B and familial MTC have also localised the gene(s) for these syndromes to the same region of chromosome 10. Recently, germline mutations in the RET proto-oncogene have been identified in patients with MEN 2A, MEN 2B and familial MTC. To date, mis-sense mutations in exons 10 or 11 have been reported in greater than 95% of the MEN 2A families studied and in approximately 80% of families with familial MTC alone. All of the mutations described thus far involve 5 conserved cysteine residues. Of the MEN 2B families examined, none had mutations in exon 10 or 11 of the RET gene. Rather, a point mutation in codon 918 of exon 16 of the RET proto-oncogene has been identified in the majority of these families. Since a germline mutation may not be identified for all affected individuals, the most accurate assessment will be obtained when an affected individual is tested to verify the type of mutation present before testing at risk family members. Analysis::
Blood: 3 x 4.0mL whole blood into EDTA tubes . Invert several times to mix. Forward within 24-48 hours at ambient temperature. Paediatric Samples:: Prenatal Samples:
Paraffin blocks of tissue are also acceptable. The tissue sample should not have had prolonged immersion in formalin before embedding. NOTE:
6 weeks once sample is received. Cost of test: MEN 2A - $847.83 MEN 2B - $463.81 Note: Prices excludes GST (12.5%) and may change without notice. Please click on a link below to view information about another specific test.
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