A multitude of molecular methods are currently used for identification and characterization of or... more A multitude of molecular methods are currently used for identification and characterization of oral biofilms or for community profiling. However, multiplex PCR techniques that are able to routinely identify several species in a single assay are not available. Multiplex Ligation-dependent Probe Amplification (MLPA) identifies up to 45 unique fragments in a single tube PCR. Here we report a novel use of MLPA in the relative quantification of targeted microorganisms in a community of oral microbiota. We designed 9 species specific probes for: Actinomyces gerencseriae, Actinomyces naeslundii, Actinomyces odontolyticus, Candida albicans, Lactobacillus acidophilus, Rothia dentocariosa, Streptococcus mutans, Streptococcus sanguinis and Veillonella parvula; and genus specific probes for selected oral Streptococci and Lactobacilli based on their 16S rDNA sequences. MLPA analysis of DNA pooled from the strains showed the expected specific MLPA products. Relative quantification of a serial dilution of equimolar DNA showed that as little as 10 pg templates can be detected with clearly discernible signals. Moreover, a 2 to 7% divergence in relative signal ratio of amplified probes observed from normalized peak area values suggests MLPA can be a cheaper alternative to using qPCR for quantification. We observed 2 to 6 fold fluctuations in signal intensities of MLPA products in DNAs isolated from multispecies biofilms grown in various media for various culture times. Furthermore, MLPA analyses of DNA isolated from saliva obtained from different donors gave a varying number and intensity of signals. This clearly shows the usefulness of MLPA in a quantitative description of microbial shifts.
Objectives: Formation of collateral circulation is an endogenous response to atherosclerosis, and... more Objectives: Formation of collateral circulation is an endogenous response to atherosclerosis, and is a natural escape mechanism by re-routing blood. Inflammatory response- related genes underlie the formation of coronary collaterals. We explored the genetic basis of collateral formation in man postulating interaction networks between functional Single Nucleotide Polymorphisms (SNPs) in these inflammatory gene candidates. Methods: The contribution of 41 genes as well as the interactions among them was examined in a cohort of 226 coronary artery disease patients, genotyped for 54 candidate SNPs. Patients were classified to the extent of collateral circulation. Stepwise logistic regression analysis and a haplotype entropy procedure were applied to search for haplotype interactions among all 54 polymorphisms. Multiple testing was addressed by using the false discovery rate (FDR) method. Results: The population comprised 84 patients with and 142 without visible collaterals. Among the 41 ...
Background— Mutations in the plakophilin-2 gene ( PKP2 ) have been found in patients with arrhyth... more Background— Mutations in the plakophilin-2 gene ( PKP2 ) have been found in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC). Hence, genetic screening can potentially be a valuable tool in the diagnostic workup of patients with ARVC. Methods and Results— To establish the prevalence and character of PKP2 mutations and to study potential differences in the associated phenotype, we evaluated 96 index patients, including 56 who fulfilled the published task force criteria. In addition, 114 family members from 34 of these 56 ARVC index patients were phenotyped. In 24 of these 56 ARVC patients (43%), 14 different (11 novel) PKP2 mutations were identified. Four different mutations were found more than once; haplotype analyses revealed identical haplotypes in the different mutation carriers, suggesting founder mutations. No specific genotype-phenotype correlations could be identified, except that negative T waves in V 2 and V 3 occurred more often in PKP2 mutati...
Atrial fibrillation (AF), the most common cardiac arrhythmia, is characterised by rapid and irreg... more Atrial fibrillation (AF), the most common cardiac arrhythmia, is characterised by rapid and irregular contraction of the atrium. The risk of AF increases with age and AF increases the risk of various heart disorders, stroke and mortality. AF can occur in a sporadic or familial form. The underlying mechanism leading to AF is not well known but genetic analysis can increase our insight into the molecular pathways in AF. Detailed information on the molecular mechanisms of a disorder increase options for diagnosis and treatment. Recently, a gain-of-function mutation in exon of the KCNQ1 gene located on chromosome 11 was identified in a large Chinese AF family. KCNQ1 associates with KCNE1 or KCNE2 (both located on chromosome 21) to form cardiac potassium channels. Subsequent analysis of Chinese families showed a KCNE2 mutation in two families. Other genetic studies show linkage to chromosome 6 and 10, indicating genetic heterogeneity. A number of studies have shown that altered expressio...
Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family me... more Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family members develop numerous colorectal adenomas with a virtually 100% chance of malignant degeneration unless the colon is prophylactically removed. After colectomy the main cause of death is upper gastrointestinal malignancy. The majority of FAP patients also develop upper gastrointestinal polyps, and especially those in the antrum and duodenum are usually neoplastic. Therefore, surveillance of FAP patients through endoscopy plus biopsy is recommended. The Spigelman classification in which the number of adenomas, the size, architecture and degree of dysplasia account for the scoring system, provides a guide for follow-up in these patients. Molecular genetic markers to assess the risk of upper gastrointestinal cancer in FAP patients are as yet not available.
Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic.... more Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic. Nevertheless, an increased cancer risk both within and outside the gastrointestinal tract may exist in these syndromes. The hamartomatous polyps may sometimes harbor dysplasia, but their neoplastic potential is unknown. The genetic defects causing the hamartomatous syndromes are less well established than, for example, familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC). The genetic studies on the Mendelian inherited syndromes FAP and HNPCC have made a major contribution to the identification of genes involved in colorectal tumorigenesis. The genes involved in colorectal cancer development may also contribute to cancer development in the hamartomatous polyposis syndromes, and are currently under investigation. Furthermore, new insights into the development of various cancers may be obtained by the isolation and characterization of genes involved i...
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastrointestinal hamartomas and adenocarcinomas in PJS patients. Linkage analysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19p13.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, STK11, were identified in all six families by sequencing genomic DNA. Analysis of hamartomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STK11 in 70% of tumors. Haplotype analysis indicated that the retained allele carried a germ-line mutation, confirming that STK11 is a tumor suppressor gene. LOH of 17p and 18q was iden...
Clinical cancer research : an official journal of the American Association for Cancer Research, 2000
Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a p... more Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a phenotypic feature of the Muir-Torre syndrome (MTS). A subset of patients with MTS have a variant of the hereditary nonpolyposis colorectal cancer syndrome caused by mutations in mismatch repair (MMR) genes, which lead to microsatellite instability (MSI). We evaluated the value of MSI and loss of expression of the MMR genes, hMLH-1 and hMSH-2, as a marker to identify and distinguish MTS from sporadic SGC. Using a nationwide pathology report database system, we identified patients with the MTS phenotype. SGCs from 10 MTS patients and the colorectal carcinomas from 3 additional MTS patients were collected. In addition, SGCs from eight patients without a history of visceral neoplasm were collected. MSI was detected in 9 of 13 MTS-associated tumors (69%) versus 0 of 8 sporadic SGCs (P = 0.002). Except for the age of onset of colorectal carcinoma [58 years in the MSI-positive group versus 69.8...
Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a p... more Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a phenotypic feature of the Muir-Torre syndrome (MTS). A subset of patients with MTS have a variant of the hereditary nonpolyposis colorectal cancer syndrome caused by mutations in mismatch repair (MMR) genes, which lead to microsatellite instability (MSI). We evaluated the value of MSI and loss of expression of the MMR genes, hMLH-1 and hMSH-2, as a marker to identify and distinguish MTS from sporadic SGC. Using a nationwide pathology report database system, we identified patients with the MTS phenotype. SGCs from 10 MTS patients and the colorectal carcinomas from 3 additional MTS patients were collected. In addition, SGCs from eight patients without a history of visceral neoplasm were collected. MSI was detected in 9 of 13 MTS-associated tumors (69%) versus 0 of 8 sporadic SGCs (P5 0.002). Except for the age of onset of colorectal carcinoma [58 years in the MSI-positive group versus 69.8 ...
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous mela nin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastroin testinal hamartomas and adenocarcinomas in PJS patients. Linkage anal ysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19pl3.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, S'l'Kll. were iden tified in all six families by sequencing genomic DNA. Analysis of hamar tomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STKil in 70% of tumors. Haplotype analysis indicated that the retained alÃ-elecarried a germ-line mutation, confirming that SI hi I is a tumor suppressor gene. LOH of 17p...
Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family me... more Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family members develop numerous colorectal adenomas with a virtually 100% chance of malignant degeneration unless the colon is prophylactically removed. After colectomy the main cause of death is upper gastrointestinal malignancy. The majority of FAP patients also develop upper gastrointestinal polyps, and especially those in the antrum and duodenum are usually neoplastic. Therefore, surveillance of FAP patients through endoscopy plus biopsy is recommended. The Spigelman classification in which the number of adenomas, the size, architecture and degree of dysplasia account for the scoring system, provides a guide for follow-up in these patients. Molecular genetic markers to assess the risk of upper gastrointestinal cancer in FAP patients are as yet not available.
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastrointestinal hamartomas and adenocarcinomas in PJS patients. Linkage analysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19p13.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, STK11, were identified in all six families by sequencing genomic DNA. Analysis of hamartomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STK11 in 70% of tumors. Haplotype analysis indicated that the retained allele carried a germ-line mutation, confirming that STK11 is a tumor suppressor gene. LOH of 17p and 18q was iden...
Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic.... more Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic. Nevertheless, an increased cancer risk both within and outside the gastrointestinal tract may exist in these syndromes. The hamartomatous polyps may sometimes harbor dysplasia, but their neoplastic potential is unknown. The genetic defects causing the hamartomatous syndromes are less well established than, for example, familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC). The genetic studies on the Mendelian inherited syndromes FAP and HNPCC have made a major contribution to the identification of genes involved in colorectal tumorigenesis. The genes involved in colorectal cancer development may also contribute to cancer development in the hamartomatous polyposis syndromes, and are currently under investigation. Furthermore, new insights into the development of various cancers may be obtained by the isolation and characterization of genes involved i...
Aim: To investigate whether mutations in the STK11/LKB1 gene and genes implicated in the colorect... more Aim: To investigate whether mutations in the STK11/LKB1 gene and genes implicated in the colorectal adenoma-carcinoma sequence are involved in Peutz-Jeghers syndrome (PJS) related tumorigenesis. Methods: We analysed 39 polyps and 5 carcinomas of 17 PJS patients from 13 families for loss of heterozygosity (LOH) at 19pl3.3 (STK11/LKB1 gene locus), 5q21 (APC gene locus), 18q21-22 (Smad4 and Smad2 gene locus) and 17pl3 (p53 gene locus) and evaluated immunohistochemical staining for p53. Also, mutational analysis of K-ras codon 12, APC and p53 and immunohistochemistry for Smad4 expression was performed on all carcinomas. Results: LOH at 19p was observed in 38% (15/39) of the polyps and in all carcinomas (n=5). Interestingly, 86% (6/7) of polyps from patients with cancer had LOH, versus 29% (9/31) of polyps from the remaining patients (p=0.01). In 1 polyp from a patient without a germline STK11/LKB1 mutation, no LOH at 19p, or at three alternative PJS candidate loci (19q, 6p and 6q) was found. No LOH at 5q was observed. However, mutational analysis revealed an APC mutation in 4 out of 5 carcinomas. LOH at 17p was not observed in polyps and carcinomas; immunohistochemistry showed expression of p53 in 1 carcinoma and focal expression in 3 polyps. At subsequent sequence analysis, no p53 mutation was found. One carcinoma had an activating K-ras codon 12 mutation and another carcinoma showed 18q LOH, however, no loss of Smad4 expression was seen. Conclusions: These results provide further evidence that STK11/LKB1 acts as a tumorsuppressor gene, and may be involved in early stages of PJS-tumorigenesis. Further research is needed to investigate whether LOH in PJS-polyps can serve as a biomarker to predict cancer. Differences in molecular genetic alterations noted between the adenoma-carcinoma sequence and PJS-related tumors suggest the presence of a distinct pathway of carcinogenesis.
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous mela nin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastroin testinal hamartomas and adenocarcinomas in PJS patients. Linkage anal ysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19pl3.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, S'l'Kll. were iden tified in all six families by sequencing genomic DNA. Analysis of hamar tomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STKil in 70% of tumors. Haplotype analysis indicated that the retained alÃ-elecarried a germ-line mutation, confirming that SI hi I is a tumor suppressor gene. LOH of 17p and 18q was identified in an adenocarcinoma but not in hamartomas, implying that allelic loss of these two regions corresponds to late molec ular events in the pathogenesis of cancer in PJS. The adenocarcinomas showing 17]>LOH also demonstrated altered p53 by immunohistochemistry. None of the 18 PJS tumors showed microsatellite instability, LOH on 5q near APC, or mutations in codons 12 or 13 of the K-ras proto oncogene. These data provide evidence that STK1ÃOE is a tumor suppressor gene that acts as an early gatekeeper regulating the development of hamartomas in PJS and suggest that hamartomas may be pathogenetic precursors of adenocarcinoma. Additional somatic mutational events un derlie the progression of hamartomas to adenocarcinomas, and some of these somatic mutations are common to the later stages of tumor progres sion seen in the majority of colorectal carcinomas.
A multitude of molecular methods are currently used for identification and characterization of or... more A multitude of molecular methods are currently used for identification and characterization of oral biofilms or for community profiling. However, multiplex PCR techniques that are able to routinely identify several species in a single assay are not available. Multiplex Ligation-dependent Probe Amplification (MLPA) identifies up to 45 unique fragments in a single tube PCR. Here we report a novel use of MLPA in the relative quantification of targeted microorganisms in a community of oral microbiota. We designed 9 species specific probes for: Actinomyces gerencseriae, Actinomyces naeslundii, Actinomyces odontolyticus, Candida albicans, Lactobacillus acidophilus, Rothia dentocariosa, Streptococcus mutans, Streptococcus sanguinis and Veillonella parvula; and genus specific probes for selected oral Streptococci and Lactobacilli based on their 16S rDNA sequences. MLPA analysis of DNA pooled from the strains showed the expected specific MLPA products. Relative quantification of a serial dilution of equimolar DNA showed that as little as 10 pg templates can be detected with clearly discernible signals. Moreover, a 2 to 7% divergence in relative signal ratio of amplified probes observed from normalized peak area values suggests MLPA can be a cheaper alternative to using qPCR for quantification. We observed 2 to 6 fold fluctuations in signal intensities of MLPA products in DNAs isolated from multispecies biofilms grown in various media for various culture times. Furthermore, MLPA analyses of DNA isolated from saliva obtained from different donors gave a varying number and intensity of signals. This clearly shows the usefulness of MLPA in a quantitative description of microbial shifts.
Objectives: Formation of collateral circulation is an endogenous response to atherosclerosis, and... more Objectives: Formation of collateral circulation is an endogenous response to atherosclerosis, and is a natural escape mechanism by re-routing blood. Inflammatory response- related genes underlie the formation of coronary collaterals. We explored the genetic basis of collateral formation in man postulating interaction networks between functional Single Nucleotide Polymorphisms (SNPs) in these inflammatory gene candidates. Methods: The contribution of 41 genes as well as the interactions among them was examined in a cohort of 226 coronary artery disease patients, genotyped for 54 candidate SNPs. Patients were classified to the extent of collateral circulation. Stepwise logistic regression analysis and a haplotype entropy procedure were applied to search for haplotype interactions among all 54 polymorphisms. Multiple testing was addressed by using the false discovery rate (FDR) method. Results: The population comprised 84 patients with and 142 without visible collaterals. Among the 41 ...
Background— Mutations in the plakophilin-2 gene ( PKP2 ) have been found in patients with arrhyth... more Background— Mutations in the plakophilin-2 gene ( PKP2 ) have been found in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC). Hence, genetic screening can potentially be a valuable tool in the diagnostic workup of patients with ARVC. Methods and Results— To establish the prevalence and character of PKP2 mutations and to study potential differences in the associated phenotype, we evaluated 96 index patients, including 56 who fulfilled the published task force criteria. In addition, 114 family members from 34 of these 56 ARVC index patients were phenotyped. In 24 of these 56 ARVC patients (43%), 14 different (11 novel) PKP2 mutations were identified. Four different mutations were found more than once; haplotype analyses revealed identical haplotypes in the different mutation carriers, suggesting founder mutations. No specific genotype-phenotype correlations could be identified, except that negative T waves in V 2 and V 3 occurred more often in PKP2 mutati...
Atrial fibrillation (AF), the most common cardiac arrhythmia, is characterised by rapid and irreg... more Atrial fibrillation (AF), the most common cardiac arrhythmia, is characterised by rapid and irregular contraction of the atrium. The risk of AF increases with age and AF increases the risk of various heart disorders, stroke and mortality. AF can occur in a sporadic or familial form. The underlying mechanism leading to AF is not well known but genetic analysis can increase our insight into the molecular pathways in AF. Detailed information on the molecular mechanisms of a disorder increase options for diagnosis and treatment. Recently, a gain-of-function mutation in exon of the KCNQ1 gene located on chromosome 11 was identified in a large Chinese AF family. KCNQ1 associates with KCNE1 or KCNE2 (both located on chromosome 21) to form cardiac potassium channels. Subsequent analysis of Chinese families showed a KCNE2 mutation in two families. Other genetic studies show linkage to chromosome 6 and 10, indicating genetic heterogeneity. A number of studies have shown that altered expressio...
Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family me... more Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family members develop numerous colorectal adenomas with a virtually 100% chance of malignant degeneration unless the colon is prophylactically removed. After colectomy the main cause of death is upper gastrointestinal malignancy. The majority of FAP patients also develop upper gastrointestinal polyps, and especially those in the antrum and duodenum are usually neoplastic. Therefore, surveillance of FAP patients through endoscopy plus biopsy is recommended. The Spigelman classification in which the number of adenomas, the size, architecture and degree of dysplasia account for the scoring system, provides a guide for follow-up in these patients. Molecular genetic markers to assess the risk of upper gastrointestinal cancer in FAP patients are as yet not available.
Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic.... more Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic. Nevertheless, an increased cancer risk both within and outside the gastrointestinal tract may exist in these syndromes. The hamartomatous polyps may sometimes harbor dysplasia, but their neoplastic potential is unknown. The genetic defects causing the hamartomatous syndromes are less well established than, for example, familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC). The genetic studies on the Mendelian inherited syndromes FAP and HNPCC have made a major contribution to the identification of genes involved in colorectal tumorigenesis. The genes involved in colorectal cancer development may also contribute to cancer development in the hamartomatous polyposis syndromes, and are currently under investigation. Furthermore, new insights into the development of various cancers may be obtained by the isolation and characterization of genes involved i...
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastrointestinal hamartomas and adenocarcinomas in PJS patients. Linkage analysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19p13.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, STK11, were identified in all six families by sequencing genomic DNA. Analysis of hamartomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STK11 in 70% of tumors. Haplotype analysis indicated that the retained allele carried a germ-line mutation, confirming that STK11 is a tumor suppressor gene. LOH of 17p and 18q was iden...
Clinical cancer research : an official journal of the American Association for Cancer Research, 2000
Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a p... more Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a phenotypic feature of the Muir-Torre syndrome (MTS). A subset of patients with MTS have a variant of the hereditary nonpolyposis colorectal cancer syndrome caused by mutations in mismatch repair (MMR) genes, which lead to microsatellite instability (MSI). We evaluated the value of MSI and loss of expression of the MMR genes, hMLH-1 and hMSH-2, as a marker to identify and distinguish MTS from sporadic SGC. Using a nationwide pathology report database system, we identified patients with the MTS phenotype. SGCs from 10 MTS patients and the colorectal carcinomas from 3 additional MTS patients were collected. In addition, SGCs from eight patients without a history of visceral neoplasm were collected. MSI was detected in 9 of 13 MTS-associated tumors (69%) versus 0 of 8 sporadic SGCs (P = 0.002). Except for the age of onset of colorectal carcinoma [58 years in the MSI-positive group versus 69.8...
Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a p... more Sebaceous gland carcinomas (SGCs) are rare malignant skin tumors occurring sporadically or as a phenotypic feature of the Muir-Torre syndrome (MTS). A subset of patients with MTS have a variant of the hereditary nonpolyposis colorectal cancer syndrome caused by mutations in mismatch repair (MMR) genes, which lead to microsatellite instability (MSI). We evaluated the value of MSI and loss of expression of the MMR genes, hMLH-1 and hMSH-2, as a marker to identify and distinguish MTS from sporadic SGC. Using a nationwide pathology report database system, we identified patients with the MTS phenotype. SGCs from 10 MTS patients and the colorectal carcinomas from 3 additional MTS patients were collected. In addition, SGCs from eight patients without a history of visceral neoplasm were collected. MSI was detected in 9 of 13 MTS-associated tumors (69%) versus 0 of 8 sporadic SGCs (P5 0.002). Except for the age of onset of colorectal carcinoma [58 years in the MSI-positive group versus 69.8 ...
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous mela nin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastroin testinal hamartomas and adenocarcinomas in PJS patients. Linkage anal ysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19pl3.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, S'l'Kll. were iden tified in all six families by sequencing genomic DNA. Analysis of hamar tomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STKil in 70% of tumors. Haplotype analysis indicated that the retained alÃ-elecarried a germ-line mutation, confirming that SI hi I is a tumor suppressor gene. LOH of 17p...
Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family me... more Familial adenomatous polyposis (FAP) is an autosomal dominant disease in which affected family members develop numerous colorectal adenomas with a virtually 100% chance of malignant degeneration unless the colon is prophylactically removed. After colectomy the main cause of death is upper gastrointestinal malignancy. The majority of FAP patients also develop upper gastrointestinal polyps, and especially those in the antrum and duodenum are usually neoplastic. Therefore, surveillance of FAP patients through endoscopy plus biopsy is recommended. The Spigelman classification in which the number of adenomas, the size, architecture and degree of dysplasia account for the scoring system, provides a guide for follow-up in these patients. Molecular genetic markers to assess the risk of upper gastrointestinal cancer in FAP patients are as yet not available.
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastrointestinal hamartomas and adenocarcinomas in PJS patients. Linkage analysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19p13.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, STK11, were identified in all six families by sequencing genomic DNA. Analysis of hamartomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STK11 in 70% of tumors. Haplotype analysis indicated that the retained allele carried a germ-line mutation, confirming that STK11 is a tumor suppressor gene. LOH of 17p and 18q was iden...
Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic.... more Hamartomatous gastrointestinal polyposis syndromes have always been considered as non-neoplastic. Nevertheless, an increased cancer risk both within and outside the gastrointestinal tract may exist in these syndromes. The hamartomatous polyps may sometimes harbor dysplasia, but their neoplastic potential is unknown. The genetic defects causing the hamartomatous syndromes are less well established than, for example, familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC). The genetic studies on the Mendelian inherited syndromes FAP and HNPCC have made a major contribution to the identification of genes involved in colorectal tumorigenesis. The genes involved in colorectal cancer development may also contribute to cancer development in the hamartomatous polyposis syndromes, and are currently under investigation. Furthermore, new insights into the development of various cancers may be obtained by the isolation and characterization of genes involved i...
Aim: To investigate whether mutations in the STK11/LKB1 gene and genes implicated in the colorect... more Aim: To investigate whether mutations in the STK11/LKB1 gene and genes implicated in the colorectal adenoma-carcinoma sequence are involved in Peutz-Jeghers syndrome (PJS) related tumorigenesis. Methods: We analysed 39 polyps and 5 carcinomas of 17 PJS patients from 13 families for loss of heterozygosity (LOH) at 19pl3.3 (STK11/LKB1 gene locus), 5q21 (APC gene locus), 18q21-22 (Smad4 and Smad2 gene locus) and 17pl3 (p53 gene locus) and evaluated immunohistochemical staining for p53. Also, mutational analysis of K-ras codon 12, APC and p53 and immunohistochemistry for Smad4 expression was performed on all carcinomas. Results: LOH at 19p was observed in 38% (15/39) of the polyps and in all carcinomas (n=5). Interestingly, 86% (6/7) of polyps from patients with cancer had LOH, versus 29% (9/31) of polyps from the remaining patients (p=0.01). In 1 polyp from a patient without a germline STK11/LKB1 mutation, no LOH at 19p, or at three alternative PJS candidate loci (19q, 6p and 6q) was found. No LOH at 5q was observed. However, mutational analysis revealed an APC mutation in 4 out of 5 carcinomas. LOH at 17p was not observed in polyps and carcinomas; immunohistochemistry showed expression of p53 in 1 carcinoma and focal expression in 3 polyps. At subsequent sequence analysis, no p53 mutation was found. One carcinoma had an activating K-ras codon 12 mutation and another carcinoma showed 18q LOH, however, no loss of Smad4 expression was seen. Conclusions: These results provide further evidence that STK11/LKB1 acts as a tumorsuppressor gene, and may be involved in early stages of PJS-tumorigenesis. Further research is needed to investigate whether LOH in PJS-polyps can serve as a biomarker to predict cancer. Differences in molecular genetic alterations noted between the adenoma-carcinoma sequence and PJS-related tumors suggest the presence of a distinct pathway of carcinogenesis.
Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamar... more Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous mela nin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastroin testinal hamartomas and adenocarcinomas in PJS patients. Linkage anal ysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19pl3.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, S'l'Kll. were iden tified in all six families by sequencing genomic DNA. Analysis of hamar tomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STKil in 70% of tumors. Haplotype analysis indicated that the retained alÃ-elecarried a germ-line mutation, confirming that SI hi I is a tumor suppressor gene. LOH of 17p and 18q was identified in an adenocarcinoma but not in hamartomas, implying that allelic loss of these two regions corresponds to late molec ular events in the pathogenesis of cancer in PJS. The adenocarcinomas showing 17]>LOH also demonstrated altered p53 by immunohistochemistry. None of the 18 PJS tumors showed microsatellite instability, LOH on 5q near APC, or mutations in codons 12 or 13 of the K-ras proto oncogene. These data provide evidence that STK1ÃOE is a tumor suppressor gene that acts as an early gatekeeper regulating the development of hamartomas in PJS and suggest that hamartomas may be pathogenetic precursors of adenocarcinoma. Additional somatic mutational events un derlie the progression of hamartomas to adenocarcinomas, and some of these somatic mutations are common to the later stages of tumor progres sion seen in the majority of colorectal carcinomas.
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