Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
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Medullary thyroid carcinoma (MTC) occurs as a component of three well-described autosomal dominant familial cancer syndromes. Multiple endocrine neoplasia type 2A (MEN 2A) is characterized by MTC, pheochromocytomas, and parathyroid hyperplasia. Patients with the rarer multiple endocrine neoplasia type 2B (MEN 2B) syndrome develop MTC and pheochromocytomas, as well as mucosal neuromas, ganglioneuromatosis of the gastrointestinal tract, and a characteristic "marfanoid" habitus. Finally, MTC is transmitted in an autosomal dominant pattern in some families without associated pheochromocytomas or parathyroid hyperplasia (familial medullary thyroid carcinoma, MTC1(2). Sixty-one members of two well-characterized kindreds segregating MTC1 and 34 [corrected] members of six families segregating MEN2B were genotyped using a panel of RFLP probes from the pericentromeric region of chromosome 10 near a locus for MEN 2A. Statistically significant linkage was observed between the chromosome 10 centromere-specific marker D10Z1 and MTC1 (maximum pairwise lod score 5.88 with 0% recombination) and D10Z1 and MEN2B (maximum pairwise lod score 3.58 with 0% recombination). A maximum multipoint lod score of 4.08 was obtained for MEN2B at the position of D10Z1. In addition, 92 members of a previously unreported large MEN2A kindred were genotyped, and linkage to the pericentromeric region of chromosome 10 is reported (maximum pairwise lod score of 11.33 with 0% recombination between MEN2A and RBP3). These results demonstrate that both a locus for familial MTC and a locus for MEN 2B map to the pericentromeric region of chromosome 10, in the same region as a locus for MEN 2A. The finding that each of these three clinically distinct familial cancer syndromes maps to the same chromosomal region suggests that all are allelic mutations at the same locus or represent a cluster of genes involved in the regulation of neuroendocrine tissue development.
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PMID:Familial medullary thyroid carcinoma and multiple endocrine neoplasia type 2B map to the same region of chromosome 10 as multiple endocrine neoplasia type 2A. 167 89

Multiple endocrine neoplasia type 2 (MEN 2) is a cancer syndrome which comprises three related disorders, MEN type 2A (MEN 2A), type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC), MEN 2A is characterized by the association of MTC, a tumour arising from thyroid C-cells, pheochromocytoma and parathyroid hyperplasia. In addition to the thyroid cancer, MEN 2B associates pheochromocytoma, mucosal neuromas, ganglioneuromatosis of the digestive tract and skeletal abnormalities. In FMTC, the MTC is the sole clinical manifestation. MEN 2 is a dominantly inherited neural crest disorder caused by germline mutations of the RET proto-oncogene. The RET gene encodes a receptor tyrosine kinase, which displays a cadherin-like domain and a cysteine rich motif in its extracellular part. Missense mutations at one of five cysteines clustered in the extra-cytoplasmic domain of RET have been identified in the majority of the MEN 2A families and in two-thirds of FMTC. A single point mutation leading to the replacement of a methionine by a threonine within the tyrosine kinase domain has been detected in almost all cases of MEN 2B. We have screened 170 french MEN 2 families and a germline mutations in the RET gene have been identified in 92% of cases. Moreover, we confirmed the significant correlation between the nature, the position of the RET mutations and the clinical phenotype. The accurate identification by DNA testing of individual predisposed to MEN 2 suggests new protocols of treatment. Thyroidectomy as early as 6 years of age in individuals with MEN 2 mutations has been recently advocated by clinicians. We further provide evidence that MEN 2A and MEN 2B mutations convert the RET proto-oncogene in a dominantly-acting transforming gene due to the ligand-independent constitutive activation of the tyrosine kinase. Finally, we have constructed transgenic mice carrying the RET gene carrying a MEN 2A mutation fused to the calcitonin gene related peptide/calcitonin promoter. Animals of three independent transgenic lines developed C-cell hyperplasia and subsequently MTC with a complete penetrance. Taken together, these findings indicate that MEN 2A form of RET is oncogenic in thyroid C-cells, and suggest that these transgenic animals should prove a valuable model for hereditary MTC. Future work should yield insights in the signaling pathways subverted by the RET-MEN 2 proteins.
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PMID:[Neural crest and multiple endocrinopathies]. 907 21

Multiple endocrine neoplasia type 2 (MEN-2) is a familial cancer syndrome inherited in an autosomal dominant fashion with age-related penetrance. The main tumour type present in all manifestations of this syndrome. MEN-2A, MEN-2B and familial medullary thyroid carcinoma (FMTC), is medullary thyroid carcinoma (MTC). MTC arises from the parafollicular or C cells of the thyroid. MEN-2A is characterised by the triad of MTC, phaeochromocytoma, and parathyroid hyperplasia. MEN-2B is characterised by features similar to those of MEN-2A, except for the absence of clinically apparent parathyroid hyperplasia, and additional stigmata including a marfanoid habitus, mucosal neuromas and ganglioneuromatosis of the gastrointestinal tract. FMTC families have MTC as their only phenotype. Missense mutations affecting conserved cysteine codons adjacent to the transmembrane domain of the RET proto-oncogene have been identified in the germline DNA of patients with MEN-2A and FMTC. A single mutation at codon 918 in the tyrosine kinase domain of the RET receptor has been associated with the MEN-2B phenotype. In a small number of FMTC families, missense point mutations have also been identified in the intracellular domain of the RET protein. RET mutation analysis of MEN-2 families has allowed the identification of genotype-phenotype correlations. While 25% of all MTCs are hereditary, the great majority of MTCs, 75%, are sporadic. Various somatic RET mutations have been identified in sporadic MTCs. In a small number of hereditary MTCs with germline mutations in RET, an additional somatic missense RET mutation has been identified. The discovery of RET mutations in MEN-2 has made possible accurate DNA-based diagnosis and predictive testing. The clinical significance of somatic RET mutations has yet to be determined.
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PMID:RET proto-oncogene mutations in multiple endocrine neoplasia type 2 and medullary thyroid carcinoma. 916 49

Causative germline missense mutations in the RET proto-oncogene have been associated with over 92% of families with the inherited cancer syndrome multiple endocrine neoplasia type 2 (MEN 2). MEN 2A is characterized primarily by medullary thyroid carcinoma (MTC) and pheochromocytoma, both tumors of neural crest origin. Parathyroid hyperplasia or adenoma is also seen in MEN 2A, but rarely in MEN 2B, which has additional stigmata, including a marfanoid habitus, mucosal neuromas, and ganglioneuromatosis of the gastrointestinal tract. In familial MTC, MTC is the only lesion present. Somatic RET mutations have also been identified in a subset of sporadic MTCs, pheochromocytomas, and rarely, small cell lung cancer, but not in sporadic parathyroid hyperplasias/adenomas or other neuroendocrine tumors. Glial cell line-derived neurotrophic factor (GDNF) and its receptor molecule GDNFR-alpha, have recently been identified as members of the RET ligand binding complex. Therefore, the genes encoding both GDNF and GDNFR-alpha are excellent candidates for a role in the pathogenesis of those MEN 2 families and sporadic neuroendocrine tumors without RET mutations. No mutations were found in the coding region of GDNF in DNA samples from 9 RET mutation negative MEN 2 individuals (comprising 6 distinct families), 12 sporadic MTCs, 17 sporadic cases of parathyroid adenoma, and 10 small cell lung cancer cell lines. Therefore, we find no evidence that mutation within the coding regions of GDNF plays a role in the genesis of MEN 2 and sporadic neuroendocrine tumors.
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PMID:Mutation analysis of glial cell line-derived neurotrophic factor, a ligand for an RET/coreceptor complex, in multiple endocrine neoplasia type 2 and sporadic neuroendocrine tumors. 928 37

Multiple Endocrine Neoplasia (MEN) is an inherited syndrome which appears in two major forms referred to as type 1 (MEN-1) and type 2 (MEN-2). MEN-1 is characterized by the occurrence of neuroendocrine parathyroid, pancreas, duodenum and pituitary lesions. In addition to these tumors adrenocortical, lipomatous and neuroendocrine tumors in other locations may develop. The genetic defect of MEN-1 has recently been identified and involves a new form of tumor suppressor gene called mu on chromosome 11q13. It codes for a protein called menin which is expressed in a variety of human tissues and organs. In MEN-1 gene carriers inactivating germline frameshift, nonsense, missense and in-frame deletion mutations scattered throughout the 10 coding exons have been identified. The MEN-2 syndrome is divided into three clinical variants referred to as MEN-2A, MEN-2B and familial medullary thyroid carcinoma (FMTC) which share medullary thyroid carcinomas as part of the disease phenotype. In MEN-2A pheochromocytomas and parathyroid hyperplasia and in MEN-2B additional skeletal abnormalities and ganglioneuromatosis may also be encountered. All three MEN-phenotypes are associated with oncogenic point mutations of the RET protooncogene on chromosome 10q11.2 which encodes a receptor-type tyrosine kinase. Its ligand--the glial cell line derived neurotropic factor (GDNF)--forms a signaling complex with the alpha type of the GDNF receptor. All neuroendocrine tumors of the different MEN-phenotypes may also occur sporadically and there are only few clinical and pathomorphological features which are helpful to discriminate sporadic from MEN-associated neuroendocrine neoplasms. The recent achievements of molecular pathology now allow for the unambiguous identification of MEN gene carriers among patients with neuroendocrine neoplasms by DNA testing for mutations in the mu and RET gene. In this overview, distinct macroscopic and histopathological features of the two MEN phenotypes will be summarized and most recent findings on the molecular pathology of these syndromes will be outlined, together with molecular methods to identify disease-gene carriers.
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PMID:Multiple endocrine neoplasia type 1 and 2: from morphology to molecular pathology 1997. 947 63

Multiple endocrine neoplasia type 2 (MEN2) and Hirschsprung's disease (HSCR) are two dominantly inherited neurocristopathies ascribed to mutations in the RET gene [Chakravarti, 1996; Pasini et al., 1996; Eng and Mulligan, 1997]. MEN2 is a cancer syndrome comprising three related clinical subtypes: (1) MEN type 2A (MEN2A; MIM# 171400) characterized by the association of medullary thyroid carcinoma (MTC), pheochromocytoma (Pheo), and hyperparathyroidism; (2) MEN type 2B (MEN2B; MIM# 162300), which includes MTC, Pheo, mucosal neuromas, ganglioneuromatosis of the digestive tract, and skeletal abnormalities; and (3) familial MTC (FMTC; MIM# 155240), defined by the sole occurrence of MTC. HSCR (MIM# 142623) is a congenital malformation caused by the absence of enteric plexuses in the hindgut, leading to bowel obstruction in neonates. The RET gene (MIM# 164761) codes for a transmembrane tyrosine kinase, a component of a multimeric complex that also comprises one of four members of a novel family of glycosylphosphatidylinositol (GPI)-anchored receptor, GFRalpha((1-4) (e.g., GFRA1, MIM# 601496; references are detailed in Baloh et al. [1998]. Four structurally related soluble factors-glial cell line-derived neurotrophic factor (GDNF), neurturin, persephin, and artemin-are the ligands of these multimolecular receptors in which the nature of the GFRalpha determines the ligand specificity of the complex [see Baloh et al., 1998, for references]. It is well documented that RET/GFRalpha-1/GDNF delivers a signal critical for the survival of the early neural crest-derived precursors that colonize the intestine below the rostral foregut and give rise to the enteric nervous plexuses [Gershon, 1997; Cacalano et al., 1998; Enomoto et al., 1998].
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PMID:Co-segregation of MEN2 and Hirschsprung's disease: the same mutation of RET with both gain and loss-of-function? 1022 Jan 48

Three infants, who presented with intestinal obstruction due to diffuse transmural intestinal ganglioneuromatosis, are described. Mutation analysis of exon 16 of the RET proto-oncogene revealed germline M918T and thus, a molecular diagnosis of multiple endocrine neoplasia type 2B (MEN 2B). Two infants developed medullary carcinoma of the thyroid. The third had a prophylactic thyroidectomy despite no obvious thyroid masses and normal calcitonin concentrations, but microscopic multifocal medullary carcinoma was found on histological examination. Early recognition of intestinal ganglioneuromatosis with germline RET M918T mutation in pseudo-Hirschsprung's disease is an indication for prophylactic thyroidectomy.
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PMID:Intestinal ganglioneuromatosis and multiple endocrine neoplasia type 2B: implications for treatment. 1036 18

Multiple endocrine neoplasia (MEN) type 2B is a heritable endocrine disorder characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, multiple mucosal neuromas, and a marfanoid habitus. Intestinal ganglioneuromatosis, corneal nerve thickening and skeletal abnormalities are also often present. The disease is inherited in an autosomal dominant fashion and is caused by a single mutation in the RET proto-oncogene, with a methionine to threonine substitution at codon 918. The MTC in MEN 2B presents at an earlier age and tends to be more aggressive than the MTC in MEN 2A. It is multicentric and bilateral and occurs as young as age 3, with early lymph node metastases. Pheochromocytoma is also often bilateral but is rarely malignant. If pheochromocytoma is detected, adrenalectomy should precede thyroidectomy to avoid intraoperative catecholamine crisis. Patients at risk for MEN 2B should undergo genetic screening in infancy. Total thyroidectomy should be performed on all patients positive for RET mutations even prior to the onset of clinical symptoms.
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PMID:Multiple endocrine neoplasia type 2B--genetic basis and clinical expression. 1135 39

We report the case of a 24-yr-old man with a typical phenotype of multiple endocrine neoplasia type 2B (MEN 2B). The patient had previously undergone minor surgery to remove multiple tumors on the lip, but he had no further examinations. MEN 2B was suspected owing to characteristic multiple ganglioneuromatosis when the patient presented with a goiter associated with high levels of plasma calcitonin and CEA. Aspiration biopsy cytology revealed medullary thyroid carcinoma (MTC), and abdominal computed tomography and nuclear scanning with metaiodobenzylguanidine revealed bilateral adrenomedullary tumors. Adrenomedullary function tests showed high levels of serum and urinary fractionated catecholamines, and genetic analysis showed a point mutation in the codon 918 (M918T) of the RET gene. The patient was diagnosed with MEN 2B and underwent right adrenalectomy and total thyroidectomy. No distant metastasis of the MTC was noted although MEN 2B had remained undiagnosed since the ganglioneuromatosis was first noticed. MEN 2B is a rare hereditary disorder, but the occurrence of characteristic ganglioneuromatosis was quite helpful in making the diagnosis.
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PMID:A case of multiple endocrine neoplasia type 2B undiagnosed for many years despite its typical phenotype. 1172 Feb 39

Hereditary medullary thyroid carcinoma (MTC) is caused by autosomal dominant gain-of-function mutations in the RET proto-oncogene. Associations between specific RET mutations (genotype) and the aggressiveness of MTC and presence or absence of other endocrine neoplasms (phenotype) are well documented. Mutations in six exons (10, 11, 13, 14, 15, and 16) located in either cysteine-rich or tyrosine kinase domains cause one of three distinctive clinical subtypes: familial MTC, multiple endocrine neoplasia (MEN) type 2A (including variants with Hirschsprung's disease and cutaneous lichen amyloidosis), and MEN 2B. Hallmarks of MEN 2A include MTC, pheochromocytoma, and hyperparathyroidism. MEN 2B is associated with an earlier onset of MTC and pheochromocytoma, the absence of hyperparathyroidism, and the presence of striking physical stigmata (e.g., coarse facies, ganglioneuromatosis, and marfanoid habitus). Familial MTC is not associated with other endocrine neoplasms; however, the accurate distinction between familial MTC and MEN 2A may be difficult in kindreds with small size, incomplete histories, or a predominance of young individuals who may not have yet fully manifested the syndrome. Genetic testing detects greater than 95% of mutation carriers and is considered the standard of care for all first-degree relatives of patients with newly diagnosed MTC. Recommendations on the timing of prophylactic thyroidectomy and the extent of surgery are based upon a model that utilizes genotype- phenotype correlations to stratify mutations into three risk levels.
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PMID:RET proto-oncogene: a review and update of genotype-phenotype correlations in hereditary medullary thyroid cancer and associated endocrine tumors. 1602 19


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