Erika Maria Monteiro Santos

Frequency of extra-colonic tumors in hereditary nonpolyposis colorectal cancer (HNPCC) and familial colorectal cancer (FCC) Brazilian families: An analysis by a Brazilian Hereditary Colorectal Cancer Institutional Registry

The two main forms of hereditary colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). Some families do not meet all the diagnostic criteria for HNPCC or FAP and are classified as familial colorectal cancer (FCC). Little information is available on the spectrum of tumors related to HNPCC and FCC in South America. Objective: To describe the frequency of malignant tumors in a group of Brazilian families with HNPCC or FCC in an Institutional Hereditary Colorectal Cancer Registry. Material and methods: The study included 61 families (29 HNPCC and 32 FCC) between January 1998 and June 2001. HNPCC families were clinically classified according to the Amsterdam Criteria I or II. FCC families were characterized by the presence of at least two individuals with CRC or extra-colonic tumors associated with the HNPCC spectrum, at least one of them being under 50 years of age. Results: In the 29 families with HNPCC, 201 patients with cancer were identified among 1241 individuals (589 men and 652 women). Among the 201 patients 223 tumors were observed: 137 CRC (55 in men and 82 in women) and 86 extra-colonic (37 in men and 49 in women). In the 32 families with FCC, 146 patients with cancer were identified among 1053 individuals (505 men and 548 women); 158 tumors were observed in 146 patients, 75 CRC (33 in men and 42 in women) and 83 extra-colonic tumors (47 in men and 36 in women). The most frequent extra-colonic primary sites among the HNPCC families were: endometrium (26.5%) and breast (26.5%) (women), and stomach (35.1%) (men). Among the FCC families, the most common primary sites were: breast (27.8%) (women), and stomach (44.4%) (men). Conclusion: The high frequency of endometrial and gastric cancer found was expected, since these tumors are part of the HNPCC spectrum, but the high frequency of breast cancer requires further molecular investigation to determine a possible hereditary predisposition associated with hereditary CRC.

Characterization of germline mutations of MLH1 and MSH2 in unrelated south American suspected Lynch syndrome individuals

Lynch syndrome (LS) is an autosomal dominant syndrome that predisposes individuals to development of cancers early in life. These cancers are mainly the following: colorectal, endometrial, ovarian, small intestine, stomach and urinary tract cancers. LS is caused by germline mutations in DNA mismatch repair genes (MMR), mostly MLH1 and MSH2, which are responsible for more than 85% of known germline mutations. To search for germline mutations in MLH1 and MSH2 genes in 123 unrelated South American suspected LS patients (Bethesda or Amsterdam Criteria) DNA was obtained from peripheral blood, and PCR was performed followed by direct sequencing in both directions of all exons and intron–exon junctions regions of the MLH1 and MSH2 genes. MLH1 or MSH2 pathogenic mutations were found in 28.45% (34/123) of the individuals, where 25/57 (43.85%) fulfilled Amsterdam I, II and 9/66 (13.63%) the Bethesda criteria. The mutations found in both genes were as follows: nonsense (35.3%), frameshift (26.47%), splicing (23.52%), and missense (9%). Thirteen alterations (35.14%) were described for the first time. The data reported in this study add new information about MLH1 and MSH2 gene mutations and contribute to better characterize LS in Brazil, Uruguay and Argentina. The high rate of novel mutations demonstrates the importance of defining MLH1 and MSH2 mutations in distinct LS populations.

Ezrin expression as a prognostic marker in colorectal adenocarcinoma

Ezrin protein acts in the regulation of cytoskeletal and directly influences survival and tumor progression; there is an increase in its expression in metastatic cells and tissues in several types of cancer including colorectal cancer. 250 Patients with colorectal cancer submitted to surgery from 1995 to 2002. Protein expression was carried through by Tissue Micro Array immunohistochemical tests of paraffined neoplasic tissues and associated with clinical variables. Differentiation degree, lymph node invasion, metastasis at diagnosis, and palliative surgery were associated to a higher expression of the protein and survival. Higher expression of the Ezrin correlates with tumor aggressiveness and worse prognosis for colorectal cancer.

Integration of Genomics in Cancer Care

PURPOSE The article aims to introduce nurses to how genetics-genomics is currently integrated into cancer care from prevention to treatment and influencing oncology nursing practice. ORGANIZING CONSTRUCT An overview of genetics-genomics is described as it relates to cancer etiology, hereditary cancer syndromes, epigenetics factors, and management of care considerations. METHODS Peer-reviewed literature and expert professional guidelines were reviewed to address concepts of genetics-genomics in cancer care. FINDINGS Cancer is now known to be heterogeneous at the molecular level, with genetic and genomic factors underlying the etiology of all cancers. Understanding how these factors contribute to the development and treatment of both sporadic and hereditary cancers is important in cancer risk assessment, prevention, diagnosis, treatment, and long-term management and surveillance. CONCLUSIONS Rapidly developing advances in genetics-genomics are changing all aspects of cancer care, with implications for nursing practice. CLINICAL RELEVANCE Nurses can educate cancer patients and their families about genetic-genomic advances and advocate for use of evidence-based genetic-genomic practice guidelines to reduce cancer risk and improve outcomes in cancer management.

Clinical and Molecular Characterization of Brazilian Patients Suspected to Have Lynch Syndrome.

Lynch syndrome (LS) accounts for 3–5% of all colorectal cancers (CRC) and is inherited in an autosomal dominant fashion. This syndrome is characterized by early CRC onset, high incidence of tumors in the ascending colon, excess of synchronous/metachronous tumors and extra-colonic tumors. Nowadays, LS is regarded of patients who carry deleterious germline mutations in one of the five mismatch repair genes (MMR), mostly in MLH1 and MSH2, but also in MSH6, PMS1 and PMS2. To comprehensively characterize 116 Brazilian patients suspected for LS, we assessed the frequency of germline mutations in the three minor genes MSH6, PMS1 and PMS2 in 82 patients negative for point mutations in MLH1 and MSH2. We also assessed large genomic rearrangements by MLPA for detecting copy number variations (CNVs) in MLH1, MSH2 and MSH6 generating a broad characterization of MMR genes. The complete analysis of the five MMR genes revealed 45 carriers of pathogenic mutations, including 25 in MSH2, 15 in MLH1, four in MSH6 and one in PMS2. Eleven novel pathogenic mutations (6 in MSH2, 4 in MSH6 and one in PMS2), and 11 variants of unknown significance (VUS) were found. Mutations in the MLH1 and MSH2 genes represented 89% of all mutations (40/45), whereas the three MMR genes (MSH6, PMS1 and PMS2) accounted for 11% (5/45). We also investigated the MLH1 p.Leu676Pro VUS located in the PMS2 interaction domain and our results revealed that this variant displayed no defective function in terms of cellular location and heterodimer interaction. Additionally, we assessed the tumor phenotype of a subset of patients and also the frequency of CRC and extra-colonic tumors in 2,365 individuals of the 116 families, generating the first comprehensive portrait of the genetic and clinical aspects of patients suspected of LS in a Brazilian cohort.

A novel SYBR-based duplex qPCR for the detection of gene dosage: detection of an APC large deletion in a familial adenomatous polyposis patient with an unusual phenotype

BackgroundFamilial adenomatous polyposis (FAP) is a hereditary colorectal cancer syndrome caused by a loss of function of the APC gene. Large deletions in APC are a common cause of FAP; despite the existence of a variety of gene dosage detection methodologies, most are labor intensive and time and resource consuming.MethodsWe describe a new duplex qPCR method for gene dosage analysis based on the coamplification of a target and a reference gene in a SYBR Green reaction, followed by a comparison of the ratio between the target and the reference peaks of the melting curve for the test (patient) and control samples. The reliability of the described duplex qPCR was validated for several genes (APC, HPRT1, ATM, PTEN and BRCA1).ResultsUsing this novel gene dosage method, we have identified an APC gene deletion in a FAP patient undergoing genetic testing. Comparative genomic hybridization based on microarrays (aCGH) was used to confirm and map the extent of the deletion, revealing a 5.2 MB rearrangement (5q21.3-q22.3) encompassing the entire APC and 19 additional genes.ConclusionThe novel assay accurately detected losses and gains of one copy of the target sequences, representing a reliable and flexible alternative to other gene dosage techniques. In addition, we described a FAP patient harboring a gross deletion at 5q21.3-q22.3 with an unusual phenotype of the absence of mental impairment and dysmorphic features.

ROBO1 deletion as a novel germline alteration in breast and colorectal cancer patients

Despite one third of breast (BC) and colorectal cancer (CRC) cases having a hereditary component, only a small proportion can be explained by germline mutations. The aim of this study was to identify potential genomic alterations related to cancer predisposition. Copy number variations (CNVs) were interrogated in 113 unrelated cases fulfilling the criteria for hereditary BC/CRC and presenting non-pathogenic mutations in BRCA1, BRCA2, MLH1, MSH2, TP53, and CHEK2 genes. An identical germline deep intronic deletion of ROBO1 was identified in three index patients using two microarray platforms (Agilent 4x180K and Affymetrix CytoScan HD). The ROBO1 deletion was confirmed by quantitative PCR (qPCR). Six relatives were also evaluated by CytoScan HD Array. Genomic analysis confirmed a co-segregation of the ROBO1 deletion with the occurrence of cancer in two families. Direct sequencing revealed no pathogenic ROBO1 point mutations. Transcriptomic analysis (HTA 2.0, Affymetrix) in two breast carcinomas from a single patient revealed ROBO1 down-expression with no splicing events near the intronic deletion. Deeper in silico analysis showed several enhancer regions and a histone methylation mark in the deleted region. The ROBO1 deletion in a putative transcriptional regulatory region, its down-expression in tumor samples, and the results of the co-segregation analysis revealing the presence of the alteration in affected individuals suggest a pathogenic effect of the ROBO1 in cancer predisposition.

Risk perception among Brazilian individuals with high risk for colorectal cancer and colonoscopy

BackgroundRisk perception is considered a motivating factor for adopting preventive behaviors. This study aimed to verify the demographic characteristics and cancer family history that are predictors of risk perception and to verify if risk perception is a predictor of colonoscopy adherence.MethodsIndividuals with a family colorectal cancer history as indicated by a proband with cancer were interviewed by telephone. They responded to a questionnaire covering demographic characteristics, colonoscopy history and four questions on risk perception. Tests of multiple linear regression and logistic regression were used to identify associations between dependent and independent variables.ResultsThe 117 participants belonged to 62 families and had a mean age of 45.2 years. The majority of these individuals were female (74.4%) and from families who met the Amsterdam Criteria (54.7%). The average risk perception was 47.6%, with a median of 50%. The average population perception of individual risk was 55.4%, with a median of 50%. Variables associated with a higher risk perception were age, gender, religion, school level, income, and death of a family member. The variable predicting colonoscopy was receiving medical information regarding risk (odds ratio OR 8.40).ConclusionsWe found that family cancer history characteristics (number of relatives with cancer, risk classification) are associated with adequate risk perception. Risk perception does not predict colonoscopy in this sample. The only variable that predicted colonoscopy was receiving medical information recommending screening.

Predictive models for mutations in mismatch repair genes: implication for genetic counseling in developing countries.

BackgroundLynch syndrome (LS) is the most common form of inherited predisposition to colorectal cancer (CRC), accounting for 2-5% of all CRC. LS is an autosomal dominant disease characterized by mutations in the mismatch repair genes mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), postmeiotic segregation increased 1 (PMS1), post-meiotic segregation increased 2 (PMS2) and mutS homolog 6 (MSH6). Mutation risk prediction models can be incorporated into clinical practice, facilitating the decision-making process and identifying individuals for molecular investigation. This is extremely important in countries with limited economic resources. This study aims to evaluate sensitivity and specificity of five predictive models for germline mutations in repair genes in a sample of individuals with suspected Lynch syndrome.MethodsBlood samples from 88 patients were analyzed through sequencing MLH1, MSH2 and MSH6 genes. The probability of detecting a mutation was calculated using the PREMM, Barnetson, MMRpro, Wijnen and Myriad models. To evaluate the sensitivity and specificity of the models, receiver operating characteristic curves were constructed.ResultsOf the 88 patients included in this analysis, 31 mutations were identified: 16 were found in the MSH2 gene, 15 in the MLH1 gene and no pathogenic mutations were identified in the MSH6 gene. It was observed that the AUC for the PREMM (0.846), Barnetson (0.850), MMRpro (0.821) and Wijnen (0.807) models did not present significant statistical difference. The Myriad model presented lower AUC (0.704) than the four other models evaluated. Considering thresholds of ≥ 5%, the models sensitivity varied between 1 (Myriad) and 0.87 (Wijnen) and specificity ranged from 0 (Myriad) to 0.38 (Barnetson).ConclusionsThe Barnetson, PREMM, MMRpro and Wijnen models present similar AUC. The AUC of the Myriad model is statistically inferior to the four other models.

Contribution of rare germline copy number variations and common susceptibility loci in Lynch syndrome patients negative for mutations in the mismatch repair genes

In colorectal carcinoma (CRC), 35% of cases are known to have a hereditary component, while a lower proportion (∼5%) can be explained by known genetic factors. In this study, copy number variations (CNVs) were evaluated in 45 unrelated patients with clinical hypothesis of Lynch syndrome (Amsterdam or Bethesda criteria); negative for MLH1, MSH2, MSH6, PMS2, CHEK2*1100delC and TP53 pathogenic mutations; aiming to reveal new predisposing genes. Analyses with two different microarray platforms (Agilent 180K and Affymetrix CytoScan HD) revealed 35 rare CNVs covering 67 known genes in 22 patients. Gains (GALNT6 and GALNT11) and losses (SEMA3C) involving the same gene families related to CRC susceptibility were found among the rare CNVs. Segregation analysis performed on four relatives from one family suggested the involvement of GALNT11 and KMT2C in those at risk of developing CRC. Notably, in silico molecular analysis revealed that 61% (41/67) of the genes covered by rare CNVs were associated with cancer, mainly colorectal (17 genes). Ten common SNPs, previously associated with CRC, were genotyped in 39 index patients and 100 sporadic CRC cases. Although no significant, an increased number of risk alleles was detected in the index cases compared with the sporadic CRC patients. None of the SNPs were covered by CNVs, suggesting an independent effect of each alteration in cancer susceptibility. In conclusion, rare germline CNVs and common SNPs may contribute to an increased risk for hereditary CRC in patients with mismatch repair proficiency.