A genome-wide association study on copy-number variation identifies a 11q11 loss as a candidate susceptibility variant for colorectal cancer.

Colorectal cancer (CRC) is a complex disease, and therefore its development is determined by the combination of both environmental factors and genetic variants. Although genome-wide association studies (GWAS) of SNP variation have conveniently identified 20 genetic variants so far, a significant proportion of the observed heritability is yet to be explained. Common copy-number variants (CNVs) are one of the most important genomic sources of variability, and hence a potential source to explain part of this missing genetic fraction. Therefore, we have performed a GWAS on CNVs to explore the relationship between common structural variation and CRC development. Phase 1 of the GWAS consisted of 881 cases and 667 controls from a Spanish cohort. Copy-number status was validated by quantitative PCR for each of those common CNVs potentially associated with CRC in phase I. Subsequently, SNPs were chosen as proxies for the validated CNVs for phase II replication (1,342 Spanish cases and 1,874 Spanish controls). Four common CNVs were found to be associated with CRC and were further replicated in Phase II. Finally, we found that SNP rs1944682, tagging a 11q11 CNV, was nominally associated with CRC susceptibility (p value = 0.039; OR = 1.122). This locus has been previously related to extreme obesity phenotypes, which could suggest a relationship between body weight and CRC susceptibility.

High incidence of large deletions in the PMS2 gene in Spanish Lynch syndrome families.

Lynch syndrome (LS) is caused by germline mutations in one of the four mismatch repair (MMR) genes. Defects in this pathway lead to microsatellite instability (MSI) in DNA tumors, which constitutes the molecular hallmark of this disease. Selection of patients for genetic testing in LS is usually based on fulfillment of diagnostic clinical criteria (i.e. Amsterdam criteria or the revised Bethesda guidelines). However, following these criteria PMS2 mutations have probably been underestimated as their penetrances appear to be lower than those of the other MMR genes. The use of universal MMR study-based strategies, using MSI testing and immunohistochemical (IHC) staining, is being one proposed alternative. Besides, germline mutation detection in PMS2 is complicated by the presence of highly homologous pseudogenes. Nevertheless, specific amplification of PMS2 by long-range polymerase chain reaction (PCR) and the improvement of the analysis of large deletions/duplications by multiplex ligation-dependent probe amplification (MLPA) overcome this difficulty. By using both approaches, we analyzed 19 PMS2-suspected carriers who have been selected by clinical or universal strategies and found five large deletions and one frameshift mutation in PMS2 in six patients (31%). Owing to the high incidence of large deletions found in our cohort, we recommend MLPA analysis as the first-line method for searching germline mutations in PMS2.

Pharmacogenomics in colorectal cancer: a genome-wide association study to predict toxicity after 5-fluorouracil or FOLFOX administration.

The development of genotyping technologies has allowed for wider screening for inherited causes of variable outcomes following drug administration. We have performed a genome-wide association study (GWAS) on 221 colorectal cancer (CRC) patients that had been treated with 5-fluorouracil (5-FU), either alone or in combination with oxaliplatin (FOLFOX). A validation set of 791 patients was also studied. Seven SNPs (rs16857540, rs2465403, rs10876844, rs10784749, rs17626122, rs7325568 and rs4243761) showed evidence of association (pooled P-values 0.020, 9.426E-03, 0.010, 0.017, 0.042, 2.302E-04, 2.803E-03) with adverse drug reactions (ADRs). This is the first study to explore the genetic basis of inter-individual variation in toxicity responses to the administration of 5-FU or FOLFOX in CRC patients on a genome-wide scale.

Ganglioside-induced differentiation-associated protein-1 is mutant in Charcot-Marie-Tooth disease type 4A/8q21.

We previously localized and fine-mapped Charcot Marie Tooth 4A (CMT4A), the autosomal recessive, demyelinating peripheral neuropathy, to chromosome 8. Through additional positional cloning, we have identified a good candidate gene, encoding ganglioside-induced differentiation-associated protein-1 (GDAP1). We found three different mutations in four different Tunisian families-two nonsense and one missense mutation. How mutations in GDAP1 lead to CMT4A remains to be understood.

A novel founder MSH2 deletion in Ethiopian Jews is mainly associated with early-onset colorectal cancer.

Lynch syndrome is an inherited cancer predisposition syndrome caused by germline defects in any of the mismatch repair (MMR) genes. Diagnosis of carriers makes precision prevention, early detection, and tailored treatment possible. Herein we report a novel founder deletion of 18,758 bp, mediated by Alu repeats on both sides, detected in Ethiopian Jews. The deletion, which encompasses exon 9-10 of the MSH2 coding sequence, is associated mainly with early-onset MSH2/MSH6-deficient colorectal cancer (CRC) and liposarcoma. Testing of 35 members of 5 seemingly unrelated families of Ethiopian origin yielded 10/21 (48%) carriers, of whom 9 had CRC. Age at first tumor diagnosis ranged from 16 to 89 years. Carriers from the oldest generations were diagnosed after age 45 years (mean 57), and carriers from the younger generation were diagnosed before age 45 years (mean 30). Awareness of this founder deletion is important to improve patient diagnosis, institute surveillance from an early age, and refer patients for genetic counseling addressing the risk of bi-allelic constitutional MMR deficiency syndrome.

A two-phase case-control study for colorectal cancer genetic susceptibility: candidate genes from chromosomal regions 9q22 and 3q22.

BACKGROUND: Colorectal cancer (CRC) is the second cause of cancer-related death in the Western world. Much of the CRC genetic risk remains unidentified and may be attributable to a large number of common, low-penetrance genetic variants. Genetic linkage studies in CRC families have reported additional association with regions 9q22-31, 3q21-24, 7q31, 11q, 14q and 22q. There are several plausible candidate genes for CRC susceptibility within the aforementioned linkage regions including PTCH1, XPA and TGFBR1 in 9q22-31, and EPHB1 and MRAS in 3q21-q24. METHODS: CRC cases and matched controls were from EPICOLON, a prospective, multicentre, nationwide Spanish initiative, composed of two independent phases. Phase 1 corresponded to 515 CRC cases and 515 controls, whereas phase 2 consisted of 901 CRC cases and 909 controls. Genotyping was performed for 172 single-nucleotide polymorphisms (SNPs) in 84 genes located within regions 9q22-31 and 3q21-q24. RESULTS: None of the 172 SNPs analysed in our study could be formally associated with CRC risk. However, rs1444601 (TOPBP1) and rs13088006 (CDV3) in region 3q22 showed interesting results and may have an effect on CRC risk. CONCLUSIONS: TOPBP1 and CDV3 genetic variants on region 3q22 may modulate CRC risk. Further validation and meta-analysis should be undertaken in larger CRC cohorts.

[Caesarean risk factors during labor for a class III obese nulliparous]. / Facteurs de risque de césarienne en cours de travail pour la nullipare avec une obésité morbide.

OBJECTIVES: Obesity is a well-known caesarean and obstetrical risk factor. However, the number of obese nulliparous women is increasing worldwide, creating an urgent need for research into the impact of obesity on the mode of delivery. Our objective was to identify caesarean risk factors in obese nulliparous women with a BMI (body mass index) greater than 40kg/m2. METHODS: A literature review was conducted on PubMed; including articles published between 2009 and 2019 in French and English, on caesarean risk during labor among class III obese nulliparous women. RESULTS: One prospective study, and 6 retrospective analyses were included. Their results suggest that the rate of caesarean delivery increases with the BMI. Maternal age, particularly after 35 years, as well as induced labor and the use of oxytocin during labor, were positively associated with cesarean delivery. Moreover, maternal BMI was linked to an increased risk of non-elective caesarean section due to non-reassuring fetal heart tracing. CONCLUSION: Extreme BMI, age, induced labor and oxytocin use are associated with caesarean delivery in nulliparous women with BMI≥40kg/m2. Further research are needed to estimate the best candidates for elective cesarean delivery.

Exome sequencing of early-onset patients supports genetic heterogeneity in colorectal cancer.

Colorectal cancer (CRC) is a complex disease that can be caused by a spectrum of genetic variants ranging from low to high penetrance changes, that interact with the environment to determine which individuals will develop the disease. In this study, we sequenced 20 early-onset CRC patients to discover novel genetic variants that could be linked to the prompt disease development. Eight genes, CHAD, CHD1L, ERCC6, IGTB7, PTPN13, SPATA20, TDG and TGS1, were selected and re-sequenced in a further 304 early onset CRC patients to search for rare, high-impact variants. Although we found a recurring truncating variant in the TDG gene shared by two independent patients, the results obtained did not help consolidate any of the candidates as promising CRC predisposing genes. However, we found that potential risk alleles in our extended list of candidate variants have a tendency to appear at higher numbers in younger cases. This supports the idea that CRC onset may be oligogenic in nature and may show molecular heterogeneity. Further, larger and robust studies are thus needed to unravel the genetics behind early-onset CRC development, coupled with novel functional analyses and omic approaches that may offer complementary insight.

COGENT (COlorectal cancer GENeTics): an international consortium to study the role of polymorphic variation on the risk of colorectal cancer.

It is now recognised that a part of the inherited risk of colorectal cancer (CRC) can be explained by the co-inheritance of low-penetrance genetic variants. The accumulated experience to date in identifying these variants has served to highlight difficulties in conducting statistically and methodologically rigorous studies and follow-up analyses. The COGENT (COlorectal cancer GENeTics) consortium includes 20 research groups in Europe, Australia, the Americas, China and Japan. The overarching goal of COGENT is to identify and characterise low-penetrance susceptibility variants for CRC through association-based analyses. In this study, we review the rationale for identifying low-penetrance variants for CRC and our proposed strategy for establishing COGENT.

Founder effect of a pathogenic MSH2 mutation identified in Spanish families with Lynch syndrome.

Lynch syndrome is caused by germline mutations in the mismatch repair genes MLH1, MSH2, MSH6 or PMS2. The novel MSH2 c.[2635-3T>C; 2635-5C>T] mutation was identified in 4 Lynch families, cosegregating with the disease. This mutation, located in intron 15, was predicted to alter the correct mRNA processing by in silico analysis. Our aim was to perform the c.[2635-3T>C; 2635-5C>T] mutation screening in high risk CRC cases and control populations, to evaluate the founder effect in our population by haplotype analysis and to confirm the pathogenic effect of the mutation by MSH2 expression studies. Mutation screening was performed by SSCP and CSCE in genomic DNA from 323 high risk CRC cases and 289 controls. Haplotyping was performed analysing 4 MSH2 extragenic microsatellite markers (D2S288, D2S2227, D2S1247 and D2S1248) in 50 controls and mutation carriers by using the PHASE program. We analysed the effect of the mutation in mRNA processing by RT-PCR and in MSH2 expression by qRT-PCR using RNA from 5 mutation carriers and 18 controls. None of the remaining high risk CRC cases or controls analysed harboured the mutation. We identified a common telomeric haplotype and two centromeric haplotypes, both rare in our population. Although we were not able to identify any abnormal transcript by RT-PCR with the design used, we observed a significant reduction of mRNA MSH2 expression in carriers when compared with controls. Haplotype analyses suggest a founder effect of the c.[2635-3T>C; 2635-5C>T] MSH2 mutation and expression studies support a pathogenic role of this mutation.

[Initial evaluation, diagnosis, staging, treatment, and follow-up of patients with primary cutaneous malignant melanoma. Consensus statement of the Network of Catalan and Balearic Melanoma Centers]. / Valoración inicial, diagnóstico, estadificación, tratamiento y seguimiento de los pacientes con melanoma maligno primario de la piel. Documento de consenso de la "Xarxa de Centres de Melanoma de Catalunya i Balears"

The consensus statement on the management of primary cutaneous melanoma that we present here was based on selection, discussion, review, and comparison of recent literature (including national and international guidelines). The protocols for the diagnosis, treatment, and follow-up used in the hospital centers throughout Catalonia and the Balearic Isles belonging to the Network of Catalan and Balearic Melanoma Centers were also considered. The main objective of this statement was to present the overall management of melanoma patients typically used in our region at the present time. As such, the statement was not designed to be an obligatory protocol for health professionals caring for this group of patients, and neither can it nor should it be used for this purpose. Professionals reading the statement should not therefore consider it binding on their practice, and in no case can this text be used to guarantee or seek responsibility for a given medical opinion. The group of dermatologists who have signed this statement was created 3 years ago with the aim of making our authorities aware of the importance of this complex tumor, which, in comparison with other types of cancer, we believe does not receive sufficient attention in Spain. In addition, the regular meetings of the group have produced interesting proposals for collaboration in various epidemiological, clinical, and basic applied research projects on the subject of malignant melanoma in our society.

Comparison of predictive models, clinical criteria and molecular tumour screening for the identification of patients with Lynch syndrome in a population-based cohort of colorectal cancer patients.

BACKGROUND: Several models have recently been developed to predict mismatch repair (MMR) gene mutations. Their comparative performance with clinical criteria or universal molecular screening in a population based colorectal cancer (CRC) cohort has not been assessed. METHODS: All 1222 CRC from the EPICOLON cohort underwent tumour MMR testing with immunohistochemistry and microsatellite instability, and those with MMR deficiency (n = 91) underwent MLH1/MSH2 germline testing. Sensitivity, specificity and positive predictive value (PPV) of the PREMM(1,2) and the Barnetson models for identification of MLH1/MSH2 mutation carriers were evaluated and compared with the revised Bethesda guidelines (RBG), Amsterdam II criteria, and tumour analysis for MMR deficiency. Overall discriminative ability was quantified by the area under the ROC curve (AUC), and calibration was assessed by comparing the average predictions versus the observed prevalence. RESULTS: Both models had similar AUC (0.93 and 0.92, respectively). Sensitivity of the RBG and a PREMM(1,2) score > or =5% was 100% (95% CI 71% to 100%); a Barnetson score >0.5% missed one mutation carrier (sensitivity 87%, 95% CI 51% to 99%). PPVs of all three strategies were 2-3%. Presence of MMR deficiency increased specificity and PPV of predictive scores (97% and 21% for PREMM(1,2) score > or =5%, and 98% and 21% for Barnetson > or =0.5%, respectively). CONCLUSIONS: The PREMM(1,2) and the Barnetson models offer a quantitative systematic approach to select CRC patients for identification of MLH1/MSH2 mutation carriers with a similar performance to the RBG.

Correction of self-reported BMI based on objective measurements: a Belgian experience.

BACKGROUND: Based on successive Health Interview Surveys (HIS), it has been demonstrated that also in Belgium obesity, measured by means of a self-reported body mass index (BMI in kg/m2), is a growing public health problem that needs to be monitored as accurately as possible. Studies have shown that a self-reported BMI can be biased. Consequently, if the aim is to rely on a self-reported BMI, adjustment is recommended. Data on measured and self-reported BMI, derived from the Belgian Food Consumption Survey (FCS) 2014 offers the opportunity to do so. METHODS: The HIS and FCS are cross-sectional surveys based on representative population samples. This study focused on adults aged 18-64 years (sample HIS = 6545 and FCS = 1213). Measured and self-reported BMI collected in FCS were used to assess possible misreporting. Using FCS data, correction factors (measured BMI/self-reported BMI) were calculated in function of a combination of background variables (region, gender, educational level and age group). Individual self-reported BMI of the HIS 2013 were then multiplied with the corresponding correction factors to produce a corrected BMI-classification. RESULTS: When compared with the measured BMI, the self-reported BMI in the FCS was underestimated (mean 0.97 kg/m2). 28% of the obese people underestimated their BMI. After applying the correction factors, the prevalence of obesity based on HIS data significantly increased (from 13% based on the original HIS data to 17% based on the corrected HIS data) and approximated the measured one derived from the FCS data. CONCLUSIONS: Since self-reported calculations of BMI are underestimated, it is recommended to adjust them to obtain accurate estimates which are important for decision making.

Candidate predisposing germline copy number variants in early onset colorectal cancer patients.

PURPOSE: A great proportion of the heritability of colorectal cancer (CRC) still remains unexplained, and rare variants, as well as copy number changes, have been proposed as potential candidates to explain the so-called 'missing heritability'. We aimed to identify rare high-to-moderately penetrant copy number variants (CNVs) in patients suspected of having hereditary CRC due to an early onset. METHODS/PATIENTS: We have selected for genome-wide copy number analysis, 27 MMR-proficient early onset CRC patients (<50 years) without identifiable germline mutations in Mendelian genes related to this phenotype. Rare CNVs were selected by removing all CNVs detected at MAF >1% in the in-house control CNV database (n = 629 healthy controls). Copy number assignment was checked by duplex real-time quantitative PCR or multiplex ligation probe amplification. Somatic mutation analysis in candidate genes included: loss of heterozygosity studies, point mutation screening, and methylation status of the promoter. RESULTS: We have identified two rare germline deletions involving the AK3 and SLIT2 genes in two patients. The search for a second somatic mutational event in the corresponding CRC tumors showed loss of heterozygosity in AK3, and promoter hypermethylation in SLIT2. Both genes have been previously related to colorectal carcinogenesis. CONCLUSIONS: These findings suggest that AK3 and SLIT2 may be potential candidates involved in genetic susceptibility to CRC.

[Genetic and molecular biology techniques for the analysis of hereditary colorectal cancer]. / Técnicas de genetica y biologia molecular para el analisis del cáncer colorrectal hereditario.

The knowledge acquired in genetics and molecular biology over the last 2 decades has led to advances in the molecular diagnosis of some diseases, among them hereditary forms of colorectal cancer such as hereditary non-polyposis colorectal cancer and familial adenomatous polyposis. Moreover, the discovery of the genes causing these diseases has had implications beyond hereditary diseases since the same genes that cause hereditary forms of cancer also play a role in the much more frequent sporadic forms. Genetic diagnosis allows clinical diagnosis to be confirmed, as well as presymptomatic and even prenatal diagnoses to be made, with implications for patients with these hereditary diseases and their families.

Linkage of DFNB1 to non-syndromic neurosensory autosomal-recessive deafness in Mediterranean families.

Recent studies show a susceptibility locus (DFNB1) responsible for non-syndromic neurosensory autosomal-recessive deafness (NSRD) mapping to the pericentromeric region of chromosome 13q. In order to better understand the frequency with which DFNB1 is the gene for deafness in our patient population and the role of DFNB1 in Caucasians, we performed a genetic linkage study with four microsatellite markers linked to DFNB1 in a total of 48 independent Mediterranean families, of which 30 and 18 were of Italian and Spanish descent, respectively. A maximum two-point lod score of 7.28 was found with marker D13S115 at a recombination frequency of theta 0.1. Significant lod scores were also obtained for D13S143, D13S292 and D13S175. Genetic heterogeneity was confirmed using the HOMOG program which indicated absence of linkage to DFNB1 in approximately 21% of the sample. This study clearly demonstrates that DFNB1 plays an important role in 79% of Mediterranean families with NSRD. Furthermore, results from multipoint analysis predict that the DFNB1 gene maps between markers D13S175 and D13S115 which are separated by approximately 14.2 cM.

Linkage analysis in Spanish families with nonspecific X-linked mental retardation: Significant linkage at Xq13-q21.

Mental retardation (MR) is a genetically heterogeneous, clinically variable condition. Many cases of MR are linked to the X chromosome. The aim of this study was to identify candidate loci for nonspecific MR in Spanish samples. We selected seven families with nonspecific MR and a pattern of inheritance compatible with an X-linked disorder and a group of 26 sib pairs of mentally retarded individuals. We performed linkage analysis with a panel of 15 markers evenly distributed along the X chromosome. The study showed linkage to marker DXS8076, located in Xq21.1, by the lod score method (z = 2.11 at straight theta = 0.155) and the nonparametric extended relative pair analysis method (chi(2) = 5.32; P < 0.03). Genetic heterogeneity was found, with an estimated 75% of the families linked at recombination fraction straight theta = 0.10 to the DXS8076 locus (chi(2) = 9.51; P < 0.009). Xq13-q21 is one of the critical regions for X-linked MR previously reported, and our study supports the idea that this region may contain a locus for MR in Spanish patients.

Single-strand conformation polymorphism analysis in the FMR1 gene.

The fragile X syndrome is due to an expansion of the CGG trinucleotide repeat in the FMR1 gene and hypermethylation of its 5' upstream CpG island in about 95% of the cases. The remaining 5% of cases correspond to other molecular alterations in FMR1 gene such as partial or complete deletions, or point mutations within the coding sequence. We selected 31 patients with clinical manifestations of fragile X syndrome, scoring 16 or more in Hagerman's checklist, but without the CGG expansion. We performed single-strand conformation polymorphism analysis using a nonradioactive technique (silver staining) and we detected six anomalous migrations that, by sequence analysis, corresponded to six nucleotide changes. We screened two different populations (control and fragile X) for these changes, and concluded that they correspond to five new polymorphisms within the FMR1 gene and to one possible synonymous mutation.

Polynucleotide vaccination for cancer-treatment (review).

Inoculation with pure naked DNA in the form of plasmids can stimulate both antibody and T-cell responses in vivo against plasmid-encoded proteins. Peptide products derived from cytosolic degradation of fragments of tumour-specific proteins, expressed de novo under the transcriptional control of strong mammalian or viral promoter/enhancer signals might gain access to the MHC Class I presentation pathway, mimicking the presentation of viral proteins in infected cells. Presentation as neo-antigens or surrogate antigens in this novel context may be a means of breaking immunological tolerance, and may lead to the generation of tumour-specific immune responses.