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1.
Multiple endocrine neoplasia type 2A (MEN2A), a dominantly inherited cancer syndrome, is defined by the presence of medullary thyroid carcinoma (MTC), pheochromocytoma (pheo), and primary hyperparathyroidism (p-HPT). Along with multiple endocrine neoplasia type 2B (MEN2B) and familial medullary thyroid carcinoma (FMTC), it is associated with germline mutations of theRET proto-oncogene localized in 10q11.2. In FMTC and MEN2A, point mutations result in the substitution of one of five Cys residues in the extracellular domain ofRET. In a larger pedigree from Saarland, several individuals were observed with C-cell thyroid carcinoma. We screened 16 members of this extended family by single-strand conformation polymorphism analysis (SSCP), polymerase chain reaction (PCR), followed by restriction enzyme analysis, and by sequencing the mutated regions. In 7 family members, all of whom had been earlier operated on because of MTC, a DNA transition from T to C was observed, causing an amino acid substitution Cys634Arg. Nine members of the kindred did not carry the mutation and may be excluded from yearly biochemical testing. One of these persons seems to have been unnecessarily operated on owing to a borderline pentagastrin test.  相似文献   

2.
Multiple endocrine neoplasia type 2A (MEN 2A) and familial medullary thyroid carcinoma (FMTC) are characterized by development of medullary thyroid carcinoma (MTC) and caused by germline RET mutations. Patients with MEN 2A also develop pheochromocytoma and/or hyperparathyroidism (HPT). However, MEN 2A-affected individuals could display the FMTC phenotype at first clinical manifestation. To establish the correct phenotype and improve clinical management of patients affected by hereditary MTC, clinical screening, RET mutational analysis, penetrance of MTC, and genotype-phenotype correlation were performed in a large, suspected FMTC kindred of 86 individuals. Germline C634Y RET mutation was confirmed in 22 individuals, 15 of whom were thyroidectomized when high serum calcitonin levels were detected. MTC was confirmed in 12 individuals and C-cell hyperplasia in 3. HPT was detected in two patients. High penetrance of MTC at young age (79% at 30 yr of age) was found. This family was considered to be affected by FMTC for several years because MTC was the sole clinical manifestation. However, our results allowed reclassifying the family as MEN 2A, thereby improving clinical management of family members. Our findings regarding penetrance and genotype-phenotype correlation suggest that patients considered to have FMTC may in fact have MEN 2A in some kindreds.  相似文献   

3.
Mutations in RET proto‐oncogene cause multiple endocrine neoplasia 2A (MEN2A). Mutations in codons 609 and 611 are not frequent. We identified two MEN2A families with the Cys609Phe RET mutation, which turned out to be the same family. This mutation has been described a couple of times with no clinical details. We have characterized the clinical phenotype of this large kindred. A 54‐year‐old woman, with a medullary thyroid carcinoma (MTC), and a 33‐year‐old woman, who was operated on for an adrenal pheochromocytoma, were the index cases. 35 relatives were studied. Sixteen turned out to be carriers and 12 of them have been operated on. This family showed eight patients with C‐cell hyperplasia, six patients affected by MTC and two showing pheochromocytoma. A papillary thyroid carcinoma was also found, together with the MTC, in one of the carriers. The phenotype in this large kindred is clearly of MEN2A. In carriers presenting the Cys609Phe mutation, the timing of the presentation of the syndrome is highly unpredictable. Therefore, a strict follow up of MTC must be carried out because of risk, and pheochromocytoma should not be ignored. These results reinforce the scarce data observed on this particular mutation.  相似文献   

4.
A unilateral, apparently sporadic pheochromocytoma was removed from the right adrenal of a 73-yr-old Caucasian woman. At the time of surgery, germline DNA from the patient was not available. However, a continuous cell line (KNA) established from the tumor showed a heterozygous sequence variant TGC (cysteine) to TGG (tryptophan) in exon 10, codon 611 of the RET proto-oncogene. Subsequent genetic testing of the patient and her offspring revealed the same base-change in herself, one daughter, one son, and the only grandson, confirming hereditary disease classified as MEN2A-2. Clinical follow up of the patient revealed elevated serum calcitonin after 6 yr. Thyroidectomy was performed and revealed a small medullary thyroid carcinoma. The patient’s children thus far show no evidence of MEN2, but C-cell hyperplasia has been diagnosed in the grandson. Our serendipitous finding of a MEN2A-2 mutation in a patient with initial diagnosis of late onset, unilateral, “sporadic” pheochromocytoma would argue for routine mutation screening of even elderly patients presenting with a pheochromocytoma.  相似文献   

5.
Two mutations on the same allele of RET gene were revealed in a family with predisposition to multiple endocrine neoplasia (MEN) type 2A. The first mutation changes codon 634 from cysteine to serine. The second, a novel mutation in codon 641, changes alanine to serine in the transmembrane domain of the RET protein. Two mutations were present in close proximity in both the patients germline and tumor DNA and were absent in DNA isolated from healthy family members and control blood donors. All MEN 2A affected family members suffered from medullary thyroid carcinoma and two of ten patients for pheochromocytoma. No parathyroid gland alterations were observed in patients with two RET gene mutations. Analysis of four genetic polymorphisms in the RET gene showed higher incidence of polymorphisms of exons 11 and 15. The observed allelic imbalance in favor of mutated allele in pheochromocytoma corresponded to higher expression of the RET gene. These observations confirm the multifactorial process leading to development of MEN 2A syndrome.  相似文献   

6.
The RET proto-oncogene codes for a receptor tyrosine kinase thought to play a role in the development of neural crest and its derivatives. Mutations in the RET proto-oncogene have been found in patients with the multiple endocrine neoplasia type 2 syndromes (MEN 2), the related sporadic tumours medullary thyroid carcinoma and pheochromocytoma, and familial and sporadic Hirschsprung disease, a syndrome of congenital absence of enteric innervation. Germline mutations in one of eight codons within RET cause the three subtypes of MEN 2, namely, MEN 2A, MEN 2B, and familial medullary thyroid carcinoma. Somatic mutation in an overlapping group of nine codons have been found in a proportion of sporadic medullary thyroid carcinoma and pheochromocytoma. In contrast to MEN 2, approximately 25% of patients with Hirschsprung disease have germline mutations scattered throughout the length of RET. Hum Mutat 9:97–109, 1997. © 1997 Wiley-Liss, Inc.  相似文献   

7.
Mutation of RET codon 768 is associated with the FMTC phenotype   总被引:3,自引:0,他引:3  
Multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B), and familial medullary thyroid carcinoma (FMTC) are inherited cancer syndromes resulting from mutations in the RET proto-oncogene. Missense mutations of five codons in exons 10 and 11 are found in both MEN 2A and FMTC families, while mutations at codon 768 in exon 13 have been identified in three FMTC families. We report here the results of mutation analysis on a large multi-generation family with multiple cases of medullary thyroid carcinoma (MTC) or C-cell hyperplasia and two individuals with isolated adrenal medullary hyperplasia. A mutation in exon 13, which alters codon 768 from a GAG (Glu) to a GAC (Asp), was found to segregate with the FMTC phenotype in this family but not with the adrenal medullary hyperplasia. These findings suggest that the codon 768 mutation does not predispose to adrenal medullary hyperplasia, but is an accurate predictor of the MTC phenotype in this family.  相似文献   

8.
Medullary thyroid carcinoma occurs sporadically or as a part of the inherited cancer syndrome multiple endocrine neoplasia (MEN) type 2. The MEN 2 gene has been identified as the RET proto-oncogene on chromosome 10. In MEN 2A, RET mutations are detectable in one of five cysteine codons within exons 10 and 11 and in MEN 2B in codon 918 (exon 16). Direct DNA testing for RET proto-oncogene mutations is the method of first choice in presymptomatic screening of MEN 2 families. Gene carriers should be offered prophylactic thyroidectomy. The process of DNA analysis for RET proto-oncogene mutations is demonstrated in one family with hereditary medullary thyroid carcinoma. RET mutations were detectable in five of the nine family members at risk.Abbreviations MEN Multiple endocrine neoplasia - MTC Medullary thyroid carcinoma - FMTC Familial medullary thyroid carcinoma - PCR Polymerase chain reaction - C-cells Calcitonin-producing parafollicular cells  相似文献   

9.
Hyperparathyroidism and/or parathyroid hyperplasia, medullary thyroid carcinoma (MTC), and pheochromocytomas compose the hallmarks of the multiple endocrine neoplasia type 2A (MEN 2A) syndrome. Revisiting a report in 1939 of a patient with hyperparathyroidism and parathyroid hyperplasia led to a search for evidence of MEN 2A. From medical records and discussion with family members, longitudinal follow-up of the patient and her descendants was obtained. Molecular diagnostics were integrated in the care of subsequent generations. The literature on hyperparathyroidism and MEN 2A was reviewed. Children of the proband exhibited all components of MEN 2A and the RET mutation of 634 TGC>CGC. The pedigree was typical for this mutation. Papers on anthropologic studies demonstrate skeletal evidence of hyperparathyroidism in humans centuries ago. The initial report of the proband preceded the publications defining both MTC and MEN 2A. The values of in-depth family histories and genetic analyses are exemplified.  相似文献   

10.
Activating germline mutations in the cysteine-rich domain of the RET proto-oncogene are found in >92% of the cases of multiple endocrine neoplasia type 2A (MEN2A) and 85% of familial medullary thyroid carcinoma (FMTC). In virtually 100% of patients with identified mutations one of five cysteines is altered by a missense mutation. In a MEN2A family with 14 affected and 11 unaffected living members, hypercalcemia was diagnosed in eight patients and histological evaluation revealed parathyroid hyperplasia in all cases examined (10/10). No member of this family showed any evidence for the existence of pheochromocytoma. This is the first documentation of a family without pheochromocytoma but with a high incidence of parathyroid disease. Genetic analysis revealed the presence of an unusual heterozygous mutation in exon 11 of the RET proto-oncogene representing a duplication of 12 bp resulting in the insertion of four amino acids between codon 634 (Cys) and 635 (Arg), thus creating an additional cysteine residue.   相似文献   

11.
Objective To investigate the clinical features and mutations of RET proto-oncogene in a pedigree affectedwith multiple endocrine neoplasia type 2A (MEN 2A). Methods Clinical data of the family members was collected.Genomic DNA from peripheral blood leukocytes were extracted and subjected to PCR amplification. Exons 8, 10,11, 13, 14, 15, 16 of the RET gene was sequenced. Results A missense mutation p. C634W was detected in 8members from the family. Among them, 3 were diagnosed with pheochromocytoma, 1 with medullary thyroidcarcinoma, 1 with medullary thyroid carcinoma and pheochromocytoma, 1 with medullary thyroid carcinoma andhyperparathyroidism. One member was found with thyroid enlargement but refused further examination, and another one was identified as carrier of the RET gene mutation. Conclusion A p. C634W mutation has been detected in afamily affected with MEN2A, in which most carriers have developed clinical symptoms. RET mutation detectionshould be routinely performed for families affected with MEN2A.  相似文献   

12.
Multiple Endocrine Neoplasia (MEN) 2A is an inherited disease characterized by the development of medullary thyroid carcinoma (MTC), pheochromocytoma(PHCH) and hyperparathyroidism(HPT). It has recently been shown to be associated with germline mutations in the RET proto-oncogene. Genetic testing for RET mutations will, therefore allow the identification of people with asymptomatic MEN 2 who can be offered prophylactic thyroidectomy and biochemical screening as preventive measures. No genetic study based on RET mutation detection has been available in India so far. The aim of the present study is to detect the proportion of MTC cases having inherited germline or somatic RET mutations and to identify family members at risk for MEN and, thereby the feasibility of screening for MEN. DNA extracted from the peripheral blood and somatic (tumor) tissues were subjected to PCR using primers for exons 10,11 and 16. A few samples were subjected to direct sequencing. Germline mutations were identified in 3 of 4 MEN 2A patients, 18 of 24 sporadic MTC(SMTC), 2 of 4 children of MEN2A and 8 relatives of SMTC. Common mutation was in exon 10 and 11 (c634). It is recommended that RET mutation analysis and counseling of patients and their immediate relatives be introduced on a regular basis to identify gene carriers.  相似文献   

13.
In this article, we summarize our recent findings on rearranged during transfection (RET) mutations in a series of 46 sporadic as well as multiple endocrine neoplasia (MEN) type 2-associated tumors and present results of our family screening efforts to identify MEN 2 and MEN 1 gene carriers. A nonisotopic polymerase chain reaction-based single-strand conformation polymorphism (PCR-SSCP) analysis and heteroduplex gel electrophoresis method was used to screen DNA extracted from archival specimens of 22 patients with MEN 2-associated and 24 patients with sporadic tumors for mutations inRET exons 10, 11, 13, and 16. Point mutations were identified by nonisotopic cycle sequencing of PCR products using an automated DNA sequencer. We found six different missense germline mutations at cysteine residues encoded by exons 10 and 11 in all patients with MEN 2A or familial medullary thyroid carcinoma (FMTC). The frequency of mutations at codon 634 was higher in patients with MEN 2A than with FMTC and a634 Cys→Arg mutation was associated with parathyroid disease. A germline Met→Thr point mutation at codon 918 of theRET tyrosine kinase domain encoded by exon 16 was identified in all MEN 2B patients. Nonpredicted inheritable medullary thyroid carcinomas (MTCs) were detected in two patients and a mosaic postzygotic mutation was found in one additional patient. Tumor-specific (somatic) Met→Thr point mutations at codon 918 were identified in 5 of 13 sporadic MTCs and 2 of 8 sporadic pheochromocytomas (PCCs). The remaining sporadic tumors lacked mutations in all fourRET exons tested. In exon 13, a nucleic acid polymorphism (CTT/CTG; Leu) at codon 769 was identified, which is present in approx 40% of the examined population. Our study demonstrates that the molecular methods used are not only suitable to identify asymptomatic individuals at risk for MEN 2A, FMTC, and MEN 2B, but also to distinguish sporadic from inherited tumors using archival tissue specimens; and that more tumors than clinically expected are inheritable, indicating the need for genetic analysis of all MTC and PCC patients.  相似文献   

14.
Hypercalcitoninemia has frequently been reported as a marker for medullary thyroid carcinoma. Currently, calcitonin measurements are mostly useful in the evaluation of tumor size and progression, and as an index of biochemical improvement of medullary thyroid carcinomas. Although measurement of calcitonin is a highly sensitive method for the detection of medullary thyroid carcinoma, it presents a low specificity for this tumor. Several physiologic and pathologic conditions other than medullary thyroid carcinoma have been associated with increased levels of calcitonin. Several cases of thyroid nodules associated with increased values of calcitonin are not medullary thyroid carcinomas, but rather are related to other conditions, such as hypercalcemias, hypergastrinemias, neuroendocrine tumors, renal insufficiency, papillary and follicular thyroid carcinomas, and goiter. Furthermore, prolonged treatment with omeprazole (> 2–4 months), beta-blockers, glucocorticoids and potential secretagogues, have been associated with hypercalcitoninemia. An association between calcitonin levels and chronic auto-immune thyroiditis remains controversial. Patients with calcitonin levels >100 pg/mL have a high risk for medullary thyroid carcinoma (~90%–100%), whereas patients with values from 10 to 100 pg/mL (normal values: <8.5 pg/mL for men, < 5.0 pg/mL for women; immunochemiluminometric assay) have a <25% risk for medullary thyroid carcinoma.In multiple endocrine neoplasia type 2 (MEN2), RET mutation analysis is the gold-standard for the recommendation of total preventive thyroidectomy to relatives at risk of harboring a germline RET mutation (50%). False-positive calcitonin results within MEN2 families have led to incorrect indications of preventive total thyroidectomy to RET mutation negative relatives. In this review, we focus on the differential diagnosis of hypercalcitoninemia, underlining its importance for the avoidance of misdiagnosis of medullary thyroid carcinoma and consequent incorrect recommendation for thyroid surgery.  相似文献   

15.
Multiple endocrine neoplasia type 2 [MEN 2] is an autosomal dominant cancer syndrome with two subtypes, 2A and 2B. MEN 2A and medullary thyroid cancer [MTC] are caused by >25 different point mutations in exons 10, 11, and 13 of the RET proto-oncogene, whereas MEN 2B is caused by a single exon 16-point mutation. Various molecular methods have been used to identify the different mutations, including DNA sequencing, restriction enzymatic analyses, chemical cleavage mismatch, Single Stranded Conformational Polymorphism [SSCP], and Denaturing Gradient Gel Electrophoresis [DGGE]. These techniques, although useful and accurate, are labor intensive and some involve the use of radioactivity. We have developed a multiplex PCR assay simultaneously to amplify exons 10, 11, and 13 of the RET proto-oncogene. The multiplex PCR product is then analyzed on a modified Mutation Detection Enhancement [MDE] matrix for heteroduplex identification and visualized with ethidium bromide. Distinct heteroduplexes were detected for each known RET proto-oncogene mutation available in our laboratory (nine in exon 10, five in exon 11, one in exon 13, and the single exon 16 mutation). Presymptomatic DNA diagnosis of MEN 2 is essential since pentagastrin-stimulated calcitonin studies can occasionally produce false positive results and lead to unnecessary thyroidectomies. Prophylactic thyroidectomy is recommended by age 5 or 6 once a mutation is identified in a patient, since penetrance is very high. MDE heteroduplex detection provides a quick, efficient, and inexpensive method of screening for RET mutations in MTC patients with unknown mutations, or for presymptomatic diagnosis in individuals at risk for inheriting a known RET mutation. Confirmation of the specific mutation can be achieved by restriction enzymatic digestion (if feasible) or by DNA sequencing. © 1996 Wiley-Liss, Inc.  相似文献   

16.
RET proto-oncogene mutations in French MEN 2A and FMTC families   总被引:3,自引:0,他引:3  
Constitutional mutations of the RET proto-oncogene have beenidentified in multiple endocrine neoplasia type 2A (MEN 2A),type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC)families. We sequenced RET exons 10 and 11 in 86 unrelated patientswith an inherited predisposition to MTC (excluding MEN 2B).Germ-line mutations were Identified in 93% of the MEN 2A familiesand 67% of the FMTC families tested. All were missense mutationsaffecting one of three cysteines in the extracellular domainof the RET tyrosine kinase receptor. The prevalence of phaeochromocytomaand hyperparathyroidism was significantly higher in familieswith a mutation of cysteine 634. These data confirm the preferentiallocalisation of MEN 2A and FMTC associated mutations and thestrong correlation between clinical manifestations and the positionof RET mutation. Although direst sequencing of RET exons 10and 11 allows the identification of a constitutional mutationin a large proportion of MEN 2A and FMTC families, our datasustain the existence of other MTC predisposing mutations elsewherein RET coding or regulating region.  相似文献   

17.
Cho NH  Lee HW  Lim SY  Kang S  Jung WY  Park CS 《Pathology》2005,37(1):10-13
AIM: The molecular pathogenesis of familial multiple endocrine neoplasia (MEN) type 2 (parathyroid adenoma with medullary thyroid carcinoma and adrenal pheochromocytoma) is associated with a germ-line mutation in the RET proto-oncogene. We undertook this study to clarify the relationship between the tumorigenesis of apparently sporadic MEN type 2 component endocrine tumours and RET mutations. METHODS: Direct sequencing for RET exon 10, 11, 12, 13, 14, 15 and 16 and immunohistochemistry for RET monoclonal antibody were performed on the archival tissues of 84 cases of sporadic endocrine tumours, including 22 medullary thyroid carcinomas (MTCs), 35 adrenal pheochromocytomas (APCs), 18 paragangliomas (PGs), and nine parathyroid adenomas (PTAs). RESULTS: PCR-based direct sequencing revealed somatic point missense mutation within 22.7% of exon 13 of the RET proto-oncogene (four cases of E768D, one case of S7781) in MTCs. No RET genotype and morphological association was observed in MTCs or APCs. APCs revealed significantly lower levels of immunoexpression of RET, even versus PGs. CONCLUSIONS: The genetic mutation in RET is relatively low in incidence, and likely to play an insignificant role in the molecular pathogenesis of sporadic MTC. The molecular bases of PG and APC seem to be different despite their embryological and histological similarities.  相似文献   

18.
Multiple endocrine neoplasia type 2A (MEN 2A) and familial medullary thyroid carcinoma (FMTC) are characterized by development of medullary thyroid carcinoma (MTC) and caused by germline RET mutations. Patients with MEN 2A also develop pheochromocytoma and/or hyperparathyroidism (HPT). However, MEN 2A-affected individuals could display the FMTC phenotype at first clinical manifestation. To establish the correct phenotype and improve clinical management of patients affected by hereditary MTC, clinical screening, RET mutational analysis, penetrance of MTC, and genotype-phenotype correlation were performed in a large, suspected FMTC kindred of 86 individuals. Germline C634Y RET mutation was confirmed in 22 individuals, 15 of whom were thyroidectomized when high serum calcitonin levels were detected. MTC was confirmed in 12 individuals and C-cell hyperplasia in 3. HPT was detected in two patients. High penetrance of MTC at young age (79% at 30 yr of age) was found. This family was considered to be affected by FMTC for several years because MTC was the sole clinical manifestation. However, our results allowed reclassifying the family as MEN 2A, thereby improving clinical management of family members. Our findings regarding penetrance and genotype-phenotype correlation suggest that patients considered to have FMTC may in fact have MEN 2A in some kindreds.  相似文献   

19.
Germline missense mutations within the coding region of the RET proto-oncogene have recently been described in patients with the dominantly inherited cancer syndromes, multiple endocrine neoplasia type 2a (MEN 2a) and familial medullary thyroid carcinoma (FMTC). To date, the sequence variations occur in RET exons 10 and 11 and alter highly conserved cysteine residues in the proposed extracellular domain at codons 609, 611, 618, 620, and 634. To expedite rapid screening of populations at risk of MEN 2a or FMTC, we developed a PCR-based denaturing gradient gel electrophoresis (DGGE) strategy that detects polymorphisms occurring at all five Cys codons in both RET exons using identical gel conditions. In this report, the screening results from DGGE analysis of 15 distinct MEN 2a and FMTC mutations are shown. Each mutation generated a clearly distinguishable and unique homo- and heteroduplex band pattern. Given the highly efficient, reproducible, and sensitive nature of this approach, DGGE is particularly appropriate for rapid, large-scale screening of patients. Since prior knowledge of the RET mutation is unnecessary for analysis, DGGE is potentially valuable for distinguishing germline from seemingly sporadic medullary thyroid cancer as well as identifying novel sequence changes. © 1996 Wiley-Liss, Inc.  相似文献   

20.
We report what we believe to be the first case of a patient with multiple endocrine neoplasia type 2A (MEN 2A) and renal dysplasia associated with an RET 634 mutation. The proband presented at the age of 29 with medullary thyroid carcinoma (MTC), bilateral pheochromocytomas, and primary hyperparathyroidism. Screening of family members identified the syndrome in his father. Both the proband and his father carry RET 634 germline mutation resulting in cysteine to arginine amino acid substitution. The proband had a left nephrectomy at the age of 10 years. Histologic examination of the resected kidney revealed severe dysplasia. His father had normal renal tract on ultrasonography. The proband's clinical presentation was unusual, and initially thought to be an atypical pneumonia. Surgical management after pharmacologic alpha- and beta-blockage consisted of bilateral adrenalectomy, total thyroidectomy, and subtotal parathyroidectomy as a single procedure.  相似文献   

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