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B T Teh

Publications and source records attributed to B T Teh.

At least 55 records · Page 3Linked to original sources
PubMed2001

Association of a novel constitutional translocation t(1q;3q) with familial renal cell carcinoma.

Four cases of late onset clear cell renal cell carcinoma (RCC), a case of gastric cancer, and a case of exocrine pancreatic cancer were identified in a Japanese family. In order to elucidate the underlying mechanism for tumorigenesis in this family, extensive genetic studies were performed including routine and spectral karyotyping (SKY), fluorescence in situ hybridisation (FISH), comparative genomic hybridisation (CGH), loss of heterozygosity studies (LOH), and VHL mutation analysis. A germline translocation t(1;3)(q32-q41;q13-q21) was identified by karyotyping in five members of the family including all three RCC cases tested. The translocation was refined to t(1;3)(q32;q13.3) by FISH analysis using locus specific genomic clones, and the two breakpoints were mapped to a 5 cM region in 3q13.3 and a 3.6 cM region in 1q32. Both CGH and allelotyping using microsatellite markers showed loss of the derivative chromosome 3 carrying a 1q segment in the three familial RCCs analysed. Additional chromosomal imbalances were identified by CGH, including amplifications of chromosomes 5 and 7 and loss of 8p and 9. No germline VHL mutation was found but two different somatic mutations, a splice (IVS1-2A>C) and a frameshift (726delG), were identified in two RCCs from the same patient confirming their distinct origin. Taken together, these results firmly support a three step model for tumorigenesis in this family. A constitutional translocation t(1q;3q) increased the susceptibility to loss of the derivative chromosome 3 which is then followed by somatic mutations of the RCC related tumour suppressor gene VHL located in the remaining copy of chromosome 3.

Adenocarcinoma, Clear Cell↗
PubMed2001

Histone acetylation/deacetylation and cancer: an "open" and "shut" case?

DNA in eukaryotic cells is packaged into chromatin. The main packaging component of chromatin is the nucleosome, and this is composed of proteins known as histones. Histones can be reversibly modified in several ways, and the best characterized of these modifications is histone acetylation. This is a reversible modification, which is carried out by two families of enzymes, the histone acetyltransferases (HATs), and the histone deacetylases (HDACs). These enzymes have important activities in many cellular processes including transcription, DNA replication and cell cycle progression. The mechanisms underlying tumor formation are multifaceted, and often involve mutations or alterations of genes involved with the regulation and control of the cell cycle or cell death. Because of their important roles in the regulation of such events, enzymes that affect histone acetylation status are increasingly being associated with tumors. This article describes some of the current knowledge about histone acetyltransferases and histone deacetylases, and how their multitudinal roles in cellular events may have important roles in tumorigensis.

Acetylation↗
PubMed2000

Malignant melanoma in patients with multiple endocrine neoplasia type 1 and involvement of the MEN1 gene in sporadic melanoma.

Multiple endocrine neoplasia type 1 (MEN 1) is a familial cancer syndrome associated primarily with endocrine tumors of the parathyroids, enteropancreas and anterior pituitary. However, tumors of mesenchymal origin such as angiofibroma and collagenoma of the skin have also been associated with the syndrome. This highlights the possibility of an association between MEN 1 and some other types of tumors. Here we report 7 cases of primary malignant melanoma occurring in 7 MEN 1 families, all patients exhibiting classic features of MEN 1. Based on these findings and the previous implication of multiple melanoma tumor suppressor(s) in 11q, including the MEN1 region, we have investigated the involvement of the MEN1 gene in melanoma tumorigenesis. Mutation analysis was performed on a panel of 39 sporadic metastatic melanomas, 13 melanoma cell lines and 20 melanoma families without CDKN2A or CDK4 germline mutations. In addition, 19 sporadic metastatic tumors were screened for loss of heterozygosity (LOH) in 11q13. LOH was detected in 6 tumors (32%), and in 4 of the tumors the pattern of LOH suggested that the deletion included the MEN1 gene locus. A novel somatic nonsense mutation in exon 7 (Q349X) was identified in 1 sporadic tumor which also showed loss of the wild-type allele. We conclude that the MEN1 gene plays a role in the tumorigenesis of a small subgroup of melanoma.

Adult↗
PubMed2000

Comparative genomic hybridization reveals frequent losses of chromosomes 1p and 3q in pheochromocytomas and abdominal paragangliomas, suggesting a common genetic etiology.

Pheochromocytomas and abdominal paragangliomas are rare, catecholamine-producing tumors that arise from the chromaffin cells derived from the neural crest. We used comparative genomic hybridization (CGH) to screen for copy number changes in 23 pheochromocytomas and 11 abdominal paragangliomas. The pattern of copy number changes was similar between pheochromocytomas and paragangliomas, with the most consistent finding being loss of 1cen-p31, which was detected in 28/34 tumors (82%). Losses were also found on 3q22-25 (41%), 11p (26%), 3p13-14 (24%), 4q (21%), 2q (15%), and 11q22-23 (15%), and gains were detected on 19p (26%), 19q (24%), 17q24-qter (21%), 11cen-q13 (15%), and 16p (15%). Losses of 1p and 3q were detected in the majority of tumors, whereas gains of 19p and q, 17q, and 16p were seen only in tumors with six or more CGH alterations. This progression of genetic events did not correspond with the conversion to a malignant phenotype. CGH alterations involving chromosome 11 were more frequent in the malignant tumors, compared with the benign tumors (9/12 versus 3/16). In summary, we propose that pheochromocytomas and abdominal paragangliomas, which share many clinical features, also have a common genetic origin and that the loss of 1cen-p31 represents an early and important event in tumor development.

Abdominal Neoplasms↗
PubMed2000

Loss of heterozygosity in sporadic parathyroid tumours: involvement of chromosome 1 and the MEN1 gene locus in 11q13.

OBJECTIVE: Hyperparathyroidism (HPT) is a common endocrine disorder. Several loci of genetic interest have been identified in parathyroid tumours, including the MEN1 gene locus at 11q13; the HPT-JT region at 1q21-q32; and a putative tumour suppressor gene on 1p. We analysed these intervals, which harbour known genes or putative loci associated with familial hyperparathyroidism, in order to clarify the involvement of the respective regions in parathyroid tumourigenesis. DESIGN: We performed loss of heterozygosity (LOH) studies on 33 sporadic parathyroid tumours using a PCR based technique. A total of 22 microsatellite markers were used to analyse loci at 11q13, 1q21-q32 and 1p. Ten markers located distal on 1p, eight markers encompassed the HPT-JT region at 1q21-q32 and four markers surrounded the MEN1 gene locus at 11q13. MEN1 mutations were screened for using Single Strand Conformation Polymorphism analysis (SSCP) and automated sequencing of SSCP variants. PATIENTS: Thirty-three parathyroid glands and the corresponding blood samples were obtained from 33 patients (26 females and seven males) who underwent parathyroidectomy for primary hyperparathyroidism. RESULTS: Loss of heterozygosity was detected in 13 of 33 (39%) cases at 11q13, 6 of 33 (18%) cases at 1p, and in three of 33 (9%) cases at 1q (in conjunction with 1p loss). Only one of the 18 tumours in which LOH was detected, showed LOH at both chromosome 1 and chromosome 11. Additionally, those tumours found to exhibit LOH at 11q13 were screened for MEN1 mutations using single strand conformation polymorphism analysis (SSCP) and automated sequencing. Nine novel somatic mutations were found on the remaining allele in 13 (69%) tumours. CONCLUSIONS: This study consolidates the role of multiple loci in the pathogenesis of sporadic parathyroid tumours. The results indicate that there are at least two genetic loci involved in sporadic parathyroid tumourigenesis on chromosome 1, one of which has been linked to the distinct familial parathyroid condition, hyperparathyroidism-jaw tumour (HPT-JT) syndrome. The high frequency of loss of heterozygosity at 1p suggests the presence of a tumour suppressor at this locus.

Adenoma↗
PubMed2000

Phenotype and phenocopy: the relationship between genotype and clinical phenotype in a single large family with multiple endocrine neoplasia type 1 (MEN 1).

BACKGROUND: The majority of reports describing the natural history and prognosis of multiple endocrine neoplasia type 1 (MEN 1) utilize phenotypic rather than molecular genetic criteria to establish a diagnosis of MEN 1. OBJECTIVES AND PATIENTS: We sought to determine the spectrum of endocrine abnormality amongst 152 members (64 gene carriers and 88 noncarriers) of a large MEN 1 family in whom a determination of MEN 1 status had previously been made by phenotype screening. The predictive utility of both clinical and molecular screening techniques are described. RESULTS: A novel IVS2-3 (C-G) MEN1 mutation was identified in affected members of this family. Seven (10%) of 71 individuals satisfying clinical diagnostic criteria for MEN 1 were found to be genetically negative (excluded by mutation analysis and haplotyping) for MEN 1. These cases of MEN 1 phenocopy comprised four cases of primary hyperparathyroidism, two 'nonsecretory' pituitary adenoma and one case of coincident prolactinoma and hyperparathyroidism. Three of the patients with hyperparathyroidism had previously required parathyroidectomy and each had achieved normocalcaemia following parathyroid resection. Predictive genetic testing prospectively identified three children with the MEN 1 genotype. Serum calcium was normal at the time of their initial molecular genetic diagnosis. In each case hyperparathyroidism subsequently developed during adolescence. CONCLUSION: Multiple endocrine neoplasia type 1 phenocopy is an important differential diagnosis in patients exhibiting an multiple endocrine neoplasia type 1 phenotype. This is a relevant consideration, particularly when the diagnosis of multiple endocrine neoplasia type 1 is made using sensitive, but nonspecific, criteria such as mild hyperparathyroidism, pituitary micoadenoma, and hyperprolactinaemia. Confirmatory genetic testing should be undertaken to confirm clinical diagnoses of multiple endocrine neoplasia type 1.

Adult↗
PubMed2000

The management of familial breast cancer.

Epidemiological studies over the past several decades have consistently supported the concept that a proportion of breast cancers develop as the result of an inherited familial predisposition. However, until recently our understanding and knowledge of the underlying genetic processes involved have been limited. Current advances in molecular biology have shown that hereditary breast cancer may arise as the result of mutations of several specific gene loci including BRCA1, BRCA2, ATM gene, PTEN and p53. Several other less frequently occurring predisposition genes such as the androgen receptor gene (AR), the HNPCC genes and the oestrogen receptor gene may also be involved, but to a lesser extent. It is estimated that approximately 5-10% of all breast cancers involve one of these inherited predisposition genes, with BRCA1 and BRCA2 accounting for up to 90% of this group. Mutation analysis is complex in nature and is presently in a developmental and evolving phase, for which reason genetic testing should be offered on a selective basis and through genetic counselling clinics. This report reviews the current knowledge and roles of the various predisposition genes and discusses the management implications for both affected and nonaffected members of breast cancer families. Comprehensive and informative counselling is critical for women with an inherited predisposition to breast cancer and this has led to the evolution of familial cancer clinics involving a multi-disciplinary specialist team approach. Familial cancer clinics can provide individuals with information about their risk of developing breast cancer and offer advice regarding the various management options presently available.

Journal Article↗
PubMed2000

Familial isolated hyperparathyroidism as a variant of multiple endocrine neoplasia type 1 in a large Danish pedigree.

We report here our genetic findings of a family in which 14 members were affected with isolated primary hyperparathyroidism. Hyperparathyroidism is the main feature of multiple endocrine neoplasia type 1 (MEN1), making the recently cloned MEN1 gene a prime candidate gene in this family. Significantly positive lod scores were achieved with D11S4946 (3.36) and D11S4940 (3.53), and by combining the results from these two markers, a maximum positive lod score of 4.12 at recombination fraction 0.00 was obtained. Mutation analysis of MEN1 performed by full sequencing identified a missense mutation in exon 4, causing an amino acid change from glutamine to proline at codon 260. This mutation (Q260P) was present in all affected family members, and the inheritance of the mutation was in complete agreement with the disease-associated haplotype. In comparison with the recent functional studies of the menin protein interactions, this mutation is located in a region with little or no binding activity to JunD and activating protein-1 transcription factor. We conclude that some of the familial isolated primary hyperparathyroidism families constitute a milder variant of MEN 1, which is associated with a functionally milder missense mutation.

Adult↗
PubMed2000

A genotypic and histopathological study of a large Dutch kindred with hyperparathyroidism-jaw tumor syndrome.

Familial primary hyperparathyroidism is the main feature of 2 familial endocrine neoplasia syndromes: multiple endocrine neoplasia type 1 (MEN 1) and hyperparathyroidism-jaw tumor syndrome (HPT-JT). The latter is a recently described syndrome that has been associated with ossifying fibroma of the jaw and various types of renal lesions, including benign cysts, Wilms' tumor, and hamartomas. To further illustrate the natural history of this syndrome, we describe a large, previously unreported Dutch kindred in which 13 affected members presented with either parathyroid adenoma or carcinoma; in 5 affected individuals, cystic kidney disease was found. Additionally, pancreatic adenocarcinoma, renal cortical adenoma, papillary renal cell carcinoma, testicular mixed germ cell tumor with major seminoma component, and Hürthle cell thyroid adenoma were also identified. Linkage analysis of the family using MEN1-linked microsatellite markers and mutation analysis excluded the involvement of the MEN1 gene. Using markers from the HPT-JT region in 1q2531, cosegregation with the disease was found, with a maximum logarithm of odds score of 2.41 obtained for 6 markers using the most conservative calculation. Meiotic telomeric recombination between D1S413 and D1S477 was identified in 3 affected individuals, and when combined with previous reports, delineated the HPT-JT region to 14 centimorgan. Combined comparative genomic hybridization and loss of heterozygosity data revealed complex genetic abnormalities in the tumors, suggesting different possible genetic mechanisms for the disease. In conclusion, we report a family with hyperparathyroidism linked to chromosome 1q, and exhibiting several types of renal and endocrine tumors that have not been previously described.

Chromosome Mapping↗
PubMed2000

Linkage analysis of candidate regions in Swedish nonsyndromic cleft lip with or without cleft palate families.

OBJECTIVE: To analyze linkage of five candidate regions for nonsyndromic cleft lip with or without palate (CLP) on chromosome 2p13, 4q, 6p23, and 19q13; in addition chromosome 1q32, the locus for van der Woude syndrome, on Swedish CLP families. DESIGN: Three to five linked microsatellite markers were selected from each candidate region. Polymerase chain reaction (PCR) with fluorescent-labeled microsatellite markers was performed on DNA samples from the participating families. Electrophoresis of the PCR products was performed on a laser-fluorescent DNA sequencer. The genotype data were analyzed with multipoint linkage analysis. Modes of inheritance tested included two autosomal dominant, an autosomal recessive, and a nonparametric model. Multipoint logarithm of odds (LOD) scores were also calculated by assuming genetic heterogeneity. PARTICIPANTS: Nineteen Swedish multigenerational families with at least two first-degree relatives affected with CLP. Greater than 50% of the families studied show vertical transmission of the clefting phenotype and both inter- and intrafamilial variability were noted. RESULTS: Cumulative multipoint LOD scores for the whole group of families calculated under autosomal dominant modes of inheritance were negative in all regions and less than -2 except chromosome 6p23. LOD scores calculated under recessive inheritance and the nonparametric model were inconclusive. There was no significant evidence of genetic heterogeneity among the sample group. CONCLUSIONS: The group of Swedish CLP families did not demonstrate significant linkage to any of the five candidate regions examined. This might suggest a new but yet unknown CLP locus or loci in this family group. However, because linkage could not be excluded in some individual families, they should still be tested with candidate genes from these regions.

Chromosome Mapping↗
PubMed1999

Sporadic follicular thyroid tumors show loss of a 200-kb region in 11q13 without evidence for mutations in the MEN1 gene.

Loss of heterozygosity (LOH) in 11q13 where the tumor suppressor gene for multiple endocrine neoplasia type 1 (MEN 1) is located has been demonstrated in several tumor types, including follicular thyroid tumors, but whether the MEN1 gene is actually involved in their tumorigenesis is not known. In the present study, the involvement of the MEN1 gene in follicular thyroid tumors was investigated. By using 14 MEN1-linked microsatellite markers, LOH was demonstrated in 12 out of 60 follicular thyroid tumors: 2/18 adenomas, 4/15 atypical adenomas, 1/6 Hürthle cell adenomas, 1/9 carcinomas, 3/6 Hürthle cell carcinomas, and 1/6 anaplastic carcinomas. In the tumors with LOH, a single minimal region of overlapping deletions was mapped to the 200-kb interval between D11S4946 and D11S4939. Tumors that showed 11q13 LOH were screened for mutations of the MEN1 gene using single-strand conformation analysis. Abnormal shifts detected in seven tumors in two exons were sequenced, which revealed two different polymorphisms present in both tumor and constitutional DNA, but without somatic mutation. Taken together, these results suggest that in this region, a tumor suppressor gene other than MEN1 might be involved in the tumorigenesis of follicular thyroid tumors. Genes Chromosomes Cancer 26:35-39, 1999.

Adenocarcinoma, Follicular↗
PubMed1999

Evaluation of retinoblastoma and Ki-67 immunostaining as diagnostic markers of benign and malignant parathyroid disease.

Assessment of the malignant potential of parathyroid tumors in the absence of metastases can be difficult using morphologic criteria alone. In this study we have examined a total of 58 parathyroid tumors (31 benign, 15 malignant, and 12 equivocal) from 54 patients using immunohistochemistry with monoclonal antibodies directed against the retinoblastoma (RB) protein and the cell cycle-associated antigen Ki-67 to evaluate their role as diagnostic markers. RB protein immunoreactivity was not useful for distinguishing between benign and malignant parathyroid tumors. Analysis of the proliferation marker Ki-67 showed that there was a trend toward more intense staining in the malignant cases. The Ki-67 labeling index was highest in the parathyroid cancers (median 33) and lowest in the sporadic primary adenomas (median 2). An observation that might have clinical implications is that tumors from patients with familial hyperparathyroidism linked to chromosome 1q showed a high Ki-67 index, indicating strong proliferative activity (median 25). This correlates well with the clinical observation of tumors with malignant potential in this syndrome. Because of the considerable overlap between groups of tumors, Ki-67 is not suitable for definitive differentiation between benign and malignant tumors. However, Ki-67 may give valuable information about which patients should be followed more closely.;1999>

Antibodies, Monoclonal↗
PubMed1999

Familial acromegaly: case report and review of the literature.

Familial acromegaly is an exceptional clinical entity when not associated with features of multiple endocrine neoplasia type 1 (MEN1). We report here 3 pedigrees in each of which 2 patients have been shown to develop acromegaly. In 4 patients, clinical follow-up, and biological screening allowed to confidently exclude MEN1. Absence of mutation in the MEN1 gene after direct DNA analysis in 2 pedigrees reinforces the conviction that the families do not have MEN1. In families 1 and 2, diagnosis was made at a very early age and voluminous adenomas with suprasellar expansion were already present at the time of diagnosis. We review the 20 previous reports of familial acromegaly, some of them questionable. Our 3 families, combined with some other published pedigrees, allow the delineation of a familial form of acromegaly, distinct from MEN1. Dominant inheritance with reduced, age-dependant penetrance is the most parsimonious model to explain the recurrences. Gs protein pathway could be the site of action of the gene responsible of familial acromegaly, but no data have been published to sustain or reject this hypothesis.

Acromegaly↗