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Recognition of individuals with a genetic predisposition to gastric cancer (GC) enables preventive measures. However, the underlying cause of genetic susceptibility to gastric cancer remains largely unexplained. We performed germline whole-exome sequencing on leukocyte DNA of 54 patients from 53 families with genetically unexplained diffuse-type and intestinal-type GC to identify novel GC-predisposing candidate genes. As young age at diagnosis and familial clustering are hallmarks of genetic tumor susceptibility, we selected patients that were diagnosed below the age of 35, patients from families with two cases of GC at or below age 60 and patients from families with three GC cases at or below age 70. All included individuals were tested negative for germline CDH1 mutations before or during the study. Variants that were possibly deleterious according to in silico predictions were filtered using several independent approaches that were based on gene function and gene mutation burden in controls. Despite a rigorous search, no obvious candidate GC predisposition genes were identified. This negative result stresses the importance of future research studies in large, homogeneous cohorts.

Approximately 25-30% of colorectal cancer (CRC) cases are expected to result from a genetic predisposition, but in only 5-10% of these cases highly penetrant germline mutations are found. The remaining CRC heritability is still unexplained, and may be caused by a hitherto-undefined set of rare variants with a moderately penetrant risk. Here we aimed to identify novel risk factors for early-onset CRC using whole-exome sequencing, which was performed on a cohort of CRC individuals (n = 55) with a disease onset before 45 years of age. We searched for genes that were recurrently affected by rare variants (minor allele frequency ≤ 0.001) with potentially damaging effects and, subsequently, re-sequenced the candidate genes in a replication cohort of 174 early-onset or familial CRC individuals. Two functionally relevant genes with low frequency variants with potentially damaging effects, PTPN12 and LRP6, were found in at least three individuals. The protein tyrosine phosphatase PTP-PEST, encoded by PTPN12, is a regulator of cell motility and LRP6 is a component of the WNT-FZD-LRP5-LRP6 complex that triggers WNT signaling. All variants in LRP6 were identified in individuals with an extremely early-onset of the disease (≤30 years of age), and two of the three variants showed increased WNT signaling activity in vitro. In conclusion, we present PTPN12 and LRP6 as novel candidates contributing to the heterogeneous susceptibility to CRC.

Background: Hereditary nonpolyposis colorectal cancer HNPCC, Lynch syndrome) is a genetic disease of autosomal dominant inheritance. It is caused by a mutation in one of four genes of the DNA mismatch repair system and confers a markedly increased risk for various types of cancer, particularly of the colon and the endometrium. Its prevalence in the general population is about 1 in 500, and it causes about 2% to 3% of all colorectal cancers. Lynch syndrome is diagnosed in two steps: If it is suspected (because a patient develops cancer at an unusually young age or because of familial clustering), the tumor tissue is analyzed for evidence of deficient mismatch repair (microsatellite instability, loss of mismatch repair protein expression). If such evidence is found, a genetic mutation is sought. The identification of a pathogenic mutation confirms the diagnosis in the patient and enables predictive testing of other family members. Diagnostic evaluations for Lynch syndrome should be carried out with appropriate genetic counseling., Method: Selective literature review., Results: Prospective cohort studies from Germany, Finland and the Netherlands have shown that colorectal cancers detected by systematic colonoscopic surveillance tend to be at an earlier stage than those that are discovered after the patients present with symptoms. The Finnish study also showed an overall reduction in cancer risk from colonoscopic polypectomy at regular intervals., Conclusion: The studies conducted so far have not yet clearly documented the putative benefit of an individualized, risk-adapted surveillance strategy. Until this is done, patients with Lynch syndrome and healthy carriers of causative mutations should be monitored with annual colonoscopy and (for women) annual gynecological examination.

Background: Hereditary Breast and Ovarian Cancer Syndrome (HBOCS) and Hereditary Non-Polyposis Colorectal Cancer Syndrome (HNPCC, Lynch Syndrome) are two tumor predisposition syndromes responsible for the majority of hereditary breast and colorectal cancers. Carriers of both germline mutations in breast cancer genes BRCA1 or BRCA2 and in mismatch repair (MMR) genes MLH1, MSH2, MSH6 or PMS2 are very rare., Case Presentation: We identified germline mutations in BRCA1 and in MSH6 in a patient with increased risk for HBOC diagnosed with endometrial cancer at the age of 46 years., Conclusions: Although carriers of mutations in both MMR and BRCA genes are rare in Caucasian populations and anamnestical and histopathological findings may guide clinicians to identify these families, both syndromes can only be diagnosed through a complete gene analysis of the respective genes.

Infantile hypertrophic pyloric stenosis (IHPS) is a common childhood pathology affecting approximately 1-5 children pro 1000 newborns, with a genetic background as suggested by the familial occurrence. RET is a candidate gene for IHPS due to its role in the development of the intrinsic innervation and ganglia of the smooth musculature and the association of RET variants with another motility disorder (Hirschsprung's disease). Accordingly, we investigated RET-IHPS associations through sequencing of the complete RET coding region in 32 IHPS patients. Genotype frequencies were compared between patients and 48 controls using the Cochran-Armitage trend test or Fischer's test for exact p-values. We found 19 RET variants in IHPS, including polymorphisms in the promoter region (c.-200 G>A and c.-196 C>A). There was no statistically significant difference between the frequencies of the variants in both groups. There was no deviation from the Hardy-Weinberg equilibrium, yet a significant correlation (linkage disequilibrium) for variants in the promoter region, in exons 11, 13, 14 and 19 and in the 3' UTR. We conclude that RET variants are present in IHPS patients yet show no significant statistical association with the IHPS phenotype, suggesting at best an adjuvant role for RET in IHPS., (© Georg Thieme Verlag KG Stuttgart · New York.)

In the majority of colorectal cancers (CRCs) under clinical suspicion for a hereditary cause, the disease-causing genetic factors are still to be discovered. To identify such genetic factors we stringently selected a discovery cohort of 41 CRC index patients with microsatellite-stable tumors. All patients were below 40 years of age at diagnosis and/or exhibited an overt family history. We employed genome-wide copy number profiling using high-resolution SNP arrays on germline DNA, which resulted in the identification of novel copy number variants (CNVs) in six patients (15%) encompassing, among others, the cadherin gene CDH18, the bone morphogenetic protein antagonist family gene GREM1, and the breakpoint cluster region gene BCR. In addition, two genomic deletions were encountered encompassing two microRNA genes, hsa-mir-491/KIAA1797 and hsa-mir-646/AK309218. None of these CNVs has previously been reported in relation to CRC predisposition in humans, nor were they encountered in large control cohorts (>1,600 unaffected individuals). Since several of these newly identified candidate genes may be functionally linked to CRC development, our results illustrate the potential of this approach for the identification of novel candidate genes involved in CRC predisposition., (Copyright © 2010 UICC.)

Purpose: The RET protooncogene plays a crucial role in neural crest development; accordingly, mutations of RET cause MEN2A and familial medullary thyroid carcinoma, while the expression deregulation of RET is involved in the pathophysiology of glioblastoma multiforme (GBM) and pancreatic cancer (PDAC). The aim of this study was to evaluate if germline variants of the RET protooncogene are associated with GBM, pancreatic cancer and gastric cancer (GC)., Methods: Genomic DNA from peripheral blood was isolated from 100 patients with GBM, 65 patients with GC and 54 patients with PDAC. The coding sequence of RET promoter, exon 2 and exon 13 was amplified. Sequence variations at -5 and -1 in the promotor and in exon 2 were determined through a LightCycler assay, and analysis of exon 13 was carried out by genomic sequencing., Results: There was no significant association of the RET-promoter or exon 2 genotypes with the phenotype in the different populations, although there was an increase of the GG genotype of the -5G>A variant in all cancers compared to controls. Sequencing of exon 13 identified mutation c.2372A>T in codon 791 (Y791F) in heterozygous state in one of 100 GBM patients, in two of 65 patients with gastric cancer, in two of 54 PDAC patients and in none of the controls., Conclusions: Although our data did not reach significance in our small cohorts, we cannot rule out the involvement of the -5G promoter allele and the c.2372A>T mutation in the development of the aforementioned tumours.

Molecular sensing in the lingual mucosa and in the gastro-intestinal tract play a role in the detection of ingested harmful drugs and toxins. Therefore, genetic polymorphisms affecting the capability of initiating these responses may be critical for the subsequent efficiency of avoiding and/or eliminating possible threats to the organism. By using a tagging approach in the region of Taste Receptor 2R38 (TAS2R38) gene, we investigated all the common genetic variation of this gene region in relation to colorectal cancer risk with a case-control study in a German population (709 controls and 602 cases) and in a Czech population (623 controls and 601 cases). We found that there were no significant associations between individual SNPs of the TAS2R38 gene and colorectal cancer in the Czech or in the German population, nor in the joint analysis. However, when we analyzed the diplotypes and the phenotypes we found that the non-taster group had an increased risk of colorectal cancer in comparison to the taster group. This association was borderline significant in the Czech population, (OR = 1.28, 95% CI 0.99-1.67; P(value) = 0.058) and statistically significant in the German population (OR = 1.36, 95% CI 1.06-1.75; P(value) = 0.016) and in the joint analysis (OR = 1.34, 95% CI 1.12-1.61; P(value) = 0.001). In conclusion, we found a suggestive association between the human bitter tasting phenotype and the risk of CRC in two different populations of Caucasian origin.

Genetic susceptibility accounts for approximately 35% of all colorectal cancer (CRC). Ten common low-risk variants contributing to CRC risk have been identified through genome-wide association studies (GWASs). In our GWAS, 610 664 genotyped single-nucleotide polymorphisms (SNPs) passed the quality control filtering in 371 German familial CRC patients and 1263 controls, and replication studies were conducted in four additional case-control sets (4915 cases and 5607 controls). Known risk loci at 8q24.21 and 11q23 were confirmed, and a previously unreported association, rs12701937, located between the genes GLI3 (GLI family zinc finger 3) and INHBA (inhibin, beta A) [P = 1.1 x 10(-3), odds ratio (OR) 1.14, 95% confidence interval (CI) 1.05-1.23, dominant model in the combined cohort], was identified. The association was stronger in familial cases compared with unselected cases (P = 2.0 x 10(-4), OR 1.36, 95% CI 1.16-1.60, dominant model). Two other unreported SNPs, rs6038071, 40 kb upstream of CSNK2A1 (casein kinase 2, alpha 1 polypeptide) and an intronic marker in MYO3A (myosin IIIA), rs11014993, associated with CRC only in the familial CRC cases (P = 2.5 x 10(-3), recessive model, and P = 2.7 x 10(-4), dominant model). Three software tools successfully pointed to the overrepresentation of genes related to the mitogen-activated protein kinase (MAPK) signalling pathways among the 1340 most strongly associated markers from the GWAS (allelic P value < 10(-3)). The risk of CRC increased significantly with an increasing number of risk alleles in seven genes involved in MAPK signalling events (P(trend) = 2.2 x 10(-16), OR(per allele) = 1.34, 95% CI 1.11-1.61).

The GFI1 gene encodes a transcriptional repressor, which regulates myeloid differentiation. In the mouse, Gfi1 deficiency causes neutropenia and an accumulation of granulomonocytic precursor cells that is reminiscent of a myelodysplastic syndrome. We report here that a variant allele of GFI1 (GFI1(36N)) is associated with acute myeloid leukemia (AML) in white subjects with an odds ratio of 1.6 (P < 8 x 10(-5)). The GFI1(36N) variant occurred in 1806 AML patients with an allele frequency of 0.055 compared with 0.035 in 1691 healthy control patients in 2 independent cohorts. We observed that both GFI1 variants maintain the same activity as transcriptional repressors but differ in their regulation by the AML1/ETO (RUNX1/RUNX1T1) fusion protein produced in AML patients with a t(8;21) translocation. AML1/ETO interacts and colocalizes with the more common GFI1(36S) form in the nucleus and inhibits its repressor activity. However, the variant GFI1(36N) protein has a different subnuclear localization than GFI1(36S). As a consequence, AML1/ETO does not colocalize with GFI1(36N) and is unable to inhibit its repressor activity. We conclude that both variants of GFI1 differ in their ability to be regulated by interacting proteins and that the GFI1(36N) variant form exhibits distinct biochemical features that may confer a predisposition to AML.

The aim of the study was to assess whether genotypes in the Toll-like receptor 4 gene and in the promoter of the interleukin-18 gene are associated with the susceptibility to chronic periodontitis. 108 chronic periodontitis patients and 76 controls were genotyped for c.896A>G/1196C>T (TLR4 gene) and for c.-368G>C/ c.-838C>A (IL-18 promoter). There were no significant differences in genotype and allele distributions between the study groups. Periodontitis severity in patients with TLR4 c.896AG/1196CT genotype was significantly higher than wildtype carriers. The percentage of teeth with clinical attachment loss > or = 5 mm was 77.3% and 58.8%, respectively (p < or = 0.006, t-test). All subjects were further classified into carriers and non-carriers of at least one variant of each gene. A logistic regression analysis adjusted for gender, smoking, and age showed no association between gene variant carrier status and periodontitis (OR = 1.98, 95% CI 0.61-6.39). The results did not show that IL-18 and TLR4 variants have an effect on the susceptibility to chronic periodontitis. Considering the low number of periodontitis patients carrying TLR4 variants (11%), a comparison of the periodontitis severity depending on the genotype has to be interpreted cautiously.

The polymorphic variants at codon 72 of the p53 gene were shown to be functionally distinct in vitro, whereby the arginine (arg) variant induces apoptosis more efficiently than the proline (pro) variant. From the evidence that the DNA mismatch repair system and p53 interact to maintain genomic integrity, we hypothesized that the codon 72 variation may influence the age of onset of disease in HNPCC patients. We tested 538 patients for p53 codon 72 variants, including 167 unrelated patients with pathogenic germline mutations in MSH2 or MLH1 and colorectal carcinoma as first tumour, 126 patients with sporadic microsatellite stable colorectal cancers, and 245 healthy controls. The median age of onset was 41, 36, and 32 years for MSH2 or MLH1 mutation carriers with arg/arg, arg/pro, and pro/pro genotypes, respectively. The log rank test revealed significant differences in the age of onset between arg/arg and pro/pro individuals (p = 0.0002) and in arg/pro versus arg/arg and pro/pro individuals (p = 0.0026 and p = 0.0217, respectively). A Cox regression model indicated an additive mode of inheritance. No significant differences in age of onset were observed among different genotype carriers with microsatellite stable tumours. Our results suggest that p53 codon 72 genotypes are associated with the age of onset of colorectal carcinoma in a mismatch repair deficient background in a dose dependent manner. These findings may be relevant for preventive strategies in HNPCC.

Background: RNASEL is thought to be a susceptibility gene for hereditary prostate cancer and encodes the endoribonuclease RNase L, which has a role in apoptosis and is a candidate tumour-suppressor protein. A common sequence variation in RNASEL, Arg462Gln, has been associated with hereditary and sporadic prostate cancer, and the Gln variant has about three-fold reduced RNase activity in vitro. In view of the association between the age of onset of hereditary non-polyposis colorectal cancer and functionally different variants of P53, which play a key part in the apoptotic pathway, we aimed to assess whether the Arg462Gln variation of RNASEL affects the age of onset of hereditary non-polyposis colorectal cancer., Methods: We screened 251 patients with hereditary non-polyposis colorectal cancer who were unrelated, had pathogenic germline mutations in MSH2 (n=141) or MLH1 (n=110), and had colorectal carcinoma as the first tumour, for variation at codon 462 of RNASEL and compared them with 439 healthy controls., Findings: The median age of onset was 40 years (range 17-75) for patients with an Arg/Arg genotype at codon 462, 37 years (13-69) for patients with an Arg/Gln genotype, and 34 years (20-49) for those with a Gln/Gln genotype (p=0.0198). Only the RNASEL genotype had a significant effect on age of onset (p=0.0062) in an additive mode of inheritance. Pair-wise comparisons between genotype groups showed that the two homozygous groups (ie, Arg/Arg vs Gln/Gln) differed significantly in age of disease onset (mean age difference 4.8 years [SD 1.7], p=0.0044)., Interpretation: A sequence variation in the prostate-cancer-susceptibility gene RNASEL has a role in a different, unassociated malignant disease. Genotypes at RNASEL codon 462 are associated with age of onset of hereditary non-polyposis colorectal cancer in a dose-dependent way, and might have a role in preventive strategies for this disease.

Purpose: The aim of the study was the analysis of the involvement and phenotypic manifestations of MSH6 germline mutations in families suspected of hereditary nonpolyposis colorectal cancer (HNPCC)., Patients and Methods: Patients were preselected among 706 families by microsatellite instability, immunohistochemistry, and/or exclusion of MLH1 or MSH2 mutations and were subjected to MSH6 mutation analysis. Clinical and molecular data of MSH6 mutation families were compared with data from families with MLH1 and MSH2 mutations., Results: We identified 27 families with 24 different pathogenic MSH6 germline mutations, representing 3.8% of the total of the families, and 14.7% of all families with DNA mismatch repair (MMR) gene mutations (n = 183). The median age of onset of colorectal cancer in putative mutation carriers was 10 years higher for MSH6 (54 years; 95% CI, 51 to 56) compared with MLH1 and MSH2 (44 years; 95% CI, 43 to 45; log-rank test, P = .0038). Relative to other malignant tumors, colorectal cancer was less frequent in MSH6 families compared with MLH1 and MSH2 families (Fisher's exact test, P < .001). In contrast, the frequency of non-HNPCC-associated tumors was increased (Fisher's exact test, P < .001)., Conclusion: Later age of disease onset and lower incidence of colorectal cancer may contribute to a lower proportion of identified MSH6 mutations in families suspected of HNPCC. However, in approximately half of these families, at least one patient developed colorectal or endometrial cancer in the fourth decade of life. Therefore, a surveillance program as stringent as that for families with MLH1 or MSH2 mutations is recommended.

Background: Germline mutations in mismatch repair genes, mainly in hMLH1, hMSH2, and hMSH6, predispose to the hereditary non-polyposis colorectal cancer (HNPCC) syndrome. A substantial fraction of these mutations exists in genomic rearrangements of hMSH2 and hMLH1. In contrast, genomic rearrangements have not been reported in hMSH6., Methods: Out of 15 HNPCC or HNPCC-like patients who developed tumours with loss of hMSH6 protein expression, we selected three patients who still had no germline mutations after gene sequencing. Genomic DNA of these patients was analysed using PCR based relative quantification of hMSH6 fragments. Indicated exon deletions and amplifications were characterised by long range PCR and sequencing., Results: Genomic rearrangements were identified in two of the three patients. Breakpoint analyses showed an Alu repeat mediated deletion of 13.0 kb affecting the promoter region, exon 1, and exon 2 in one patient, and a duplication of 4.9 kb containing 1.6 kb of the 3' end of exon 4 and exon 5, integrated into intron 5, in the other patient., Conclusions: Although genomic rearrangements of hMSH6 only play a small role in the spectrum of all mutations predisposing to HNPCC, our results suggest that up to 10-20% of patients with hMSH6 negative tumours harbour germline rearrangements in this gene.

We investigated the association of polymorphisms of drug-metabolizing enzymes and susceptibility to oral cavity cancer. Polymerase chain reaction (PCR)-based analyses were performed on genomic DNA of 94 Caucasian patients in Germany and 92 healthy German controls to determine genotypes of polymorphisms in CYP1A1, GSTM1 and NAT2. For CYP1A1, the homozygous mutant genotype Val/Val did not occur. The heterozygous genotype Ile/Val (6.5% cases versus 4.3% controls) and the homozygous wild-type Ile/Ile (95.7% cases versus 93.5% controls) showed no statistically significant differences between groups (X(2)=0.47; P=0.534, Fisher's exact test, two-sided). The GSTM1 homozygous null genotype occurred more frequently in cancer patients (59.6%) compared to controls (53.3%) but this difference remained insignificant in X(2)-analysis (X(2)=1.07; P=0.587). Almost identical genotype distributions between cases and controls were found for all three NAT2 acetylators. Hence, these three genetic polymorphisms are unlikely to be associated with oral cavity cancer in the population studied.

Germline mutations in human mismatch repair (MMR) genes yield a predisposition for the hereditary nonpolyposis colon cancer (HNPCC) syndrome. In contrast to hMLH1 and hMSH2, little is known about the overall involvement of hMSH6 in colorectal cancer. We investigated 82 tumors from patients who fulfilled the Bethesda guidelines for HNPCC as well as 146 sporadic tumors, analyzing microsatellite instability and expression of the 4 MMR proteins hMSH6, hMSH2, hMLH1 and hPMS2. Four tumors with lost expression and 1 tumor with cytoplasmic expression of hMSH6 were identified. Sequence analysis revealed germline mutations in 4 of the 5 patients, including 1 patient with sporadic disease. The lost or reduced expression of hMSH2 and hMLH1 was always identical to its heterodimerization partners, hMSH6 and hPMS2, respectively. Furthermore, hMSH2 expression was reduced upon hMSH6 deficiency. Abnormal expression of 1 or more of the 4 proteins was always associated with a high level of microsatellite instability (MSI-H). Conversely, all but 1 of the 44 MSI-H tumors had abnormal expression of 1 or more of the proteins, basically excluding additional genes associated with the MSI-H phenotype. We conclude that the involvement of somatic or epigenetic hMSH6 inactivation in colorectal cancer is rare., (Copyright 2001 Wiley-Liss, Inc.)

Colorectal cancer (CRC) is one of the most common cancers in Western populations, striking both women and men at approximately equal rates. A genetic basis for the development of cancer has already been suggested by Karl Heinrich Bauer in 1928 but only since the advancement of molecular biology direct evidence has been obtained to support the notion that cancer is a genetic disease. Recent progress in our understanding of the molecular basis of the most prevalent colorectal cancer syndromes, such as hereditary nonpolyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP), is reflected by modifications in diagnosis and therapy. Identification of genetic risk factors for the development of adenomas and associated carcinomas of the colon and rectum results in predictive molecular diagnosis of malignant disease and enables preventive treatment.