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Colorectal cancer is a heterogeneous disease with multiple genomic changes that influence the clinical management of patients; thus, the search for new molecular targets remains necessary. The aim of this study was to identify genetic variants in tumor tissues from Mexican patients with colorectal cancer, using massive parallel sequencing. A total of 4813 genes were analyzed in tumoral DNA from colorectal cancer patients, using the TruSight One Sequencing panel. From these, 192 variants with clinical associations were found distributed in 168 different genes, of which 46 variants had not been previous reported in the literature or databases, although genes harboring those variants had already been described in colorectal cancer. Enrichment analysis of the affected genes was performed using Reactome software; pathway over-representation showed significance for disease, signal transduction, and immune system subsets in all patients, while exclusive subsets such as DNA repair, autophagy, and RNA metabolism were also found. Those characteristics, whether individual or shared, could give tumors specific capabilities for survival, aggressiveness, or response to treatment. Our results can be useful for future investigations targeting specific characteristics of tumors in colorectal cancer patients. The identification of exclusive or common pathways in colorectal cancer patients could be important for better diagnosis and personalized cancer treatment.

The present study aimed to analyze the methylation pattern of the MIR200 family in the colorectal tissues and peripheral blood of colorectal cancer (CRC) patients. Previous informed consent, 102 samples of colorectal tissues (tumor and adjacent normal tissues) and 40 peripheral blood samples were collected from CRC patients. Additionally, we included a reference group of 40 blood samples. DNA extraction was done for colorectal tissues and peripheral blood. For methylation-specific PCR, we used bisulfite-treated DNA and controls for methylated and unmethylated DNA were included to each assay. PCR fragments were separated by 6% polyacrylamide gel electrophoresis. Methylation-positive and methylation-negative results were confirmed by bisulfite genomic sequencing technique. We analyzed 102 colorectal tissues and 40 blood samples from 51 CRC patients. MIR200B/MIR200A/MIR429 methylation analysis discloses no differences among tissues (p>0.05). However, MIR200C/MIR141 methylation showed differences between colorectal tissues and peripheral blood of CRC patients (p

This study aimed to investigate the frequency of the somatic BRAF p. V600E in patients with colorectal cancer (CRC) in Mexico and compare it with those estimated for Latin American and Caribbean populations. One hundred and one patients with CRC with AJCC stages ranging I-IV from Western Mexico were included, out of which 55% were male and 61% had AJCC stage III-IV, with a mean age of 60 years. PCR-Sanger sequencing was used to identify the BRAF p. V600E variant. In addition, a systematic literature search in PubMed/Medline database and Google of the 42 countries in Latin America and the Caribbean led to the collection of information on the BRAF p. V600E variant frequency of 17 population reports. To compare the BRAF variant prevalence among populations, a statistical analysis was performed using GraphPad Prism V.6.0. We found that 4% of patients with CRC were heterozygous for the p. V600E variant. The χ2 test showed no significant difference (p>0.05) in p. V600E detection when comparing with other Latin American and Caribbean CRC populations, except for Chilean patients (p=0.02). Our observational study provides the first evidence on the frequency of BRAF p. V600E in patients with CRC from Western Mexico, which is 4%, but increases to 7.8% for all of Latin America and the Caribbean. The patient mean age and genetic descent on the observed frequencies of the variant in populations could influence the frequency differences.

AimsKDM1A/LSD1 and ZNF217 are involved in a protein complex that participates in transcriptional regulation. ZNF217 has been analysed in numerous cancers and its amplification has been associated with advanced stages of disease; however, a similar role for KDM1A/LSD1 has not been uncovered. In this study, we estimated the number of KDM1A/LSD1 and ZNF217 gene copies in tissue samples from patients diagnosed with colorectal cancer (CRC), as well as its association with clinicopathological features in patients with CRC.MethodsParaffin-embedded tumour samples from 50 patients with CRC with a histopathological diagnosis of CRC were included. The number of copies of KDM1A/LSD1 and ZNF217 genes was determined by fluorescence in situ hybridisation (FISH). We also analysed the association between copy numbers of selected genes and clinicopathological data based on multivariate analysis.ResultsDeletion of the KDM1A/LSD1 gene occurred in 19 samples (38%), whereas ZNF217 gene amplification was identified in 11 samples (22%). We found a significant association between lymph node metastasis or advanced tumour stage and KDM1A/LSD1 gene deletion (p value=0.0003 and p value=0.011, respectively).ConclusionsKDM1A/LSD1 gene deletion could be considered a novel prognostic biomarker of late-stage CRC.

La variación somática intraindividual (VSI) se describe como la diferencia genética entre los tejidos de un mismo individuo. La VSI se incrementa conforme avanza la edad y se asocia con alteraciones neurológicas, hematológicas e inmunes y, de manera especial, con cáncer, aunque puede no manifestar un fenotipo definido.1Para analizar la posible VSI en pacientes mexicanos con cáncer colorrectal (CCR), Yang et al.2 estudiaron el polimorfismo rs669 (c.2998 A>G, p.Ile1000Val) del gen A2M que codifica para la proteína alfa-2 macroglobulina, una inhibidora de proteasas involucrada en la progresión y proliferación del tumor. Esta variante se localiza cerca de un sitio tioéster, necesario para la función inhibidora de la proteína.

We aimed to assess the current genetics practice to manage patients with Lynch syndrome (LS) across Latin America. A Latin American LS survey was sent out to 52 centres/registries, comprising a total of 12 countries from the region. Overall, 33 centres completed the survey, of which the oldest LS registry was established in 1992 in Sao Paulo (Brazil), and the youngest this year in San Jose (Costa Rica). In total, 87% (26/30) of the participating centres/registries belonging to the nine countries are performing genetic testing. Overall, 1352 suspected families were sequenced. Pathogenic variants were identified in 34% of the families, with slightly differing distribution of variants between females and males. Path_MLH1 variants were identified in 39% of females and 50% of males (p = 0.023), while path_MSH2 were identified in 37% of females and males, followed by path_PMS2 in 11% of females and 8% of males, path_MSH6 in 13% of females and 3% of males (p 0.001) and path_EPCAM in 0.3% of females and 2% of males. In Latin America, 9 of 12 (75%) participating countries had implemented healthcare for LS. LS screening is inconsistently applied within Latin America healthcare systems because of structural differences in the healthcare systems between the countries.

Background. Lynch Syndrome (LS) is characterized by germline mutations in the DNA mismatch repair (MMR) genesMLH1,MSH2,MSH6,andPMS2. This syndrome is inherited in an autosomal dominant pattern and is characterized by early onset colorectal cancer (CRC) and extracolonic tumors. The aim of this study was to identify mutations inMMRgenes in three Mexican patients with LS.Methods. Immunohistochemical analysis was performed as a prescreening method to identify absent protein expression. PCR, Denaturing High Performance Liquid Chromatography (dHPLC), and Sanger sequencing complemented the analysis.Results. Two samples showed the absence of nuclear staining for MLH1 and one sample showed loss of nuclear staining for MSH2. The mutations found inMLH1gene were c.2103+1G>C in intron 18 and compound heterozygous mutants c.1852_1854delAAG (p.K618del) and c.1852_1853delinsGC (p.K618A) in exon 16. In theMSH2gene, we identified mutation c.638dupT (p.L213fs) in exon 3.Conclusions. This is the first report of mutations in MMR genes in Mexican patients with LS and these appear to be novel.

The Asn118Asn (rs11615) variant in the ERCC1 gene, and the Lys751Gln (rs13181) and Asp312Asn (rs1799793) variants in the ERCC2 gene have been associated with the development of varied types of cancer. The aim of the present study was to test for any association between the ERCC1 and ERCC2 gene variants and three different types of cancer in Mexican-mestizo patients. Patients and their respective controls were formed into three groups: The osteosarcoma group, with 28 patients and 97 controls; the colorectal group, with 108 patients and 119 controls; and the breast cancer group, with 71 patients and 74 controls. Genotyping was performed using TaqMan probes and quantitative polymerase chain reaction. Allele and genotype frequencies were compared using a χ2 test. Only one SNP (rs1799793) was found to be associated with breast cancer. This is the first study analyzing the SNPs in ERCC1 and ERCC2 genes and the susceptibility to cancer in Mexican-mestizo patients with osteosarcoma, and colorectal and breast cancer.

The ZNF217 gene, a potential oncogene amplified and overexpressed in several cancers including colorectal cancer (CRC), acts as a transcription factor that activates or represses target genes. The polymorphisms rs16998248 (T>A) and rs35720349 (C>T) in coronary artery disease have been associated with reduced expression of ZNF217. In this study, we analyzed the 2 polymorphisms in Mexican patients with CRC. Genotyping of rs16998248 and rs35720349 sites was performed by polymerase chain reaction-restriction fragment length polymorphism in 203 Mexican Mestizos, 101 CRC patients, and 102 healthy blood donors. Although no statistical differences regarding genotype and allele frequencies of ZNF217 polymorphisms were observed (P > 0.05), linkage disequilibrium was significant in CRC patients (r(2) = 0.39, P < 0.0001), as a result of reduced AC haplotype frequency. Thus, the AC haplotype may protect against CRC.

We analyzed a possible association between RUNX3 gene polymorphisms and haplotypes in Mexican patients with colorectal cancer (CRC). Genomic DNA samples were obtained from the peripheral blood of 176 Mexican patients with CRC at diagnosis and from 195 individuals that formed the control group. The polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism. Association was estimated by odds ratio (OR). The haplotypes and linkage disequilibrium were established using the Arlequin v3.5 software. We found that the RUNX3 polymorphisms analyzed were in Hardy-Weinberg equilibrium. The RUNX3 rs2236852 AA genotype and A allele showed association with CRC (OR = 0.39, 95%CI = 0.21-0.73, P < 0.01; OR = 0.65, 95%CI = 0.49-0.87, P < 0.01, respectively), while the rs6672420, rs11249206, and rs760805 polymorphisms did not show significant association with CRC. The TA haplotype (SNPs rs760805 and rs2236852) showed an increased risk for CRC (OR = 2.52, 95%CI = 1.47-4.30, P < 0.001). In conclusion, we found that the AA genotype and A allele of rs2236852 polymorphism confer a decreased CRC risk, while the TA haplotype appears to increase the risk of CRC development in Mexican patients.

Colorectal cancer (CRC) is characterized by enhanced expression and activity of several metalloproteinases (MMPs), including MMP13 and MMP7, which play an important role in tumor invasion and metastasis. The objective of this study was to analyze the association of functional MMP7-181A/G and MMP13-77A/G promoter polymorphisms with susceptibility to CRC in a Mexican population. Genomic DNA samples were obtained from peripheral blood of 102 CRC patients and 125 blood donors who were included as the control group. Identification of polymorphisms was based on polymerase chain reaction-restriction fragment length polymorphism methodology. The association was estimated by the odds ratio (OR) test. The results showed that MMP7-181A/G and MMP13-77A/G variants were associated with CRC. For MMP7-181A/G, the AA (P=0.02, OR=3.38, 95% confidence interval (CI)=1.16-9.84) and AG (P=0.01, OR=3.4, 95%CI=1.17-9.83) genotypes were associated with an increased risk of CRC. For MMP13-77A/G, the AA and AG genotypes were associated with CRC (AA genotype: P=0.04, OR=3.2, 95%CI=1.004-10.2; AG genotype: P=0.01, OR=4.08, 95%CI=1.3-13.07). In conclusion, AA and AG genotype carriers for both polymorphisms are at a higher risk of developing CRC in this Mexican population.

DNA repair proteins maintain DNA integrity; polymorphisms in genes coding for these proteins can increase susceptibility to colorectal cancer (CRC) development. We analyzed a possible association of MLH1 -93GA and 655AG and XRCC1 Arg194Trp and Arg399Gln polymorphisms with CRC in Mexican patients. Genomic DNA samples were obtained from peripheral blood of 108 individuals with CRC (study group) at diagnosis and 120 blood donors (control group) from Western Mexico; both groups were mestizos. The polymorphisms were detected by PCR-RFLP. Association was estimated by calculating the odds ratio (OR). We found that the MLH1 and XRCC1 polymorphisms were in Hardy- Weinberg equilibrium. The MLH1 655AG polymorphism in the 655G allele was associated with a 2-fold increase risk for CRC (OR = 2.04 and 95% confidence interval (95%CI) = 1.12-3.69; P0.01), while the MLH1 -93GA polymorphism allele was associated with a protective effect (OR = 0.60, 95%CI = 0.40-0.89; P = 0.01 in the -93A allele and OR = 0.32, 95%CI = 0.13-0.79; P = 0.01 in the AA genotype). The XRCC1 Arg194Trp and Arg399Gln polymorphisms did not show any significant associations. In conclusion, we found that MLH1 -93GA and 655AG polymorphisms are associated with CRC in Mexican patients.

Leptin and adiponectin are cytokines produced by adipose tissue with opposite effects on tumor growth: the former stimulate whereas the latter inhibit it. The objective was to analyze the association of LEP A19G and ADIPOQ+45 T/G and +276 G/T polymorphisms in Mexican patients with colorectal cancer (CRC). 68 unrelated patients with CRC (study group) and 102 blood donors (control group); all subjects were Mestizos from western Mexico. The polymorphisms were established by PCR-RFLP on DNA samples obtained from peripheral blood. The LEP A19G polymorphism showed significant differences between CRC patients and control group (p= 0.01 for G/A genotype and p= 0.02 for the recessive model G/G +G/A); yet, in the analysis stratified by gender, this difference remained significant only in males. The ADIPOQ polymorphisms did not shown any significant differences. Our results suggest that the A19G LEP polymorphism is associated with CRC in Mexican patients.

We examined the influence of the Arg194Trp, Arg280His, and Arg399Gln polymorphisms of XRCC1 (X-ray repair cross-complementing group 1) on the development of childhood acute lymphoblastic leukemia (ALL) in 120 ALL patients and 120 controls in Mexico. All of them were genotyped for these polymorphisms, using polymerase chain reaction. No significant differences in allele and genotype frequencies for any polymorphism were observed between patients and controls. Estimation of haplotypes showed the eight expected haplotypes (A-H), seven of which were found in both patients and controls; haplotype A (Arg-Arg-Arg) was the most common, whereas haplotypes F and G were absent in patients and controls, respectively. Haplotype B (Trp-Arg-Arg) was found to be associated with an increased risk of ALL (odds ratio (OR) = 1.95, 95% confidence interval (CI) = 1.13-3.37; P = 0.016), particularly in males (OR = 2.65, 95%CI = 1.25-5.63; P = 0.01). Individually, the 194Trp, 280His, and 399Gln alleles were not associated with significantly increased risk for ALL in these Mexican children.

To determine the influence of the MDR1 C3435T polymorphism on the development of childhood acute lymphoblastic leukemia (ALL), we studied 107 children with ALL and 111 healthy subjects. All subjects were genotyped for the C3435T polymorphism using the polymerase chain reaction-restriction fragment length polymorphism method. The genotype frequencies in the patients were 17% homozygous CC, 61% heterozygous CT, and 22% homozygous TT; in healthy individuals the genotype frequencies were 14% CC, 53% CT, and 33% TT. In patients with ALL the allele frequencies were 0.47 for the C allele and 0.53 for the T allele; in the healthy group these allele frequencies were 0.40 and 0.60 for the C and T alleles, respectively. No significant differences in allele frequency (p > 0.176) and genotype frequency (p > 0.255) were detected between the two groups. These findings suggest that the CT or TT genotype does not increase the risk for childhood ALL in Mexican patients. On the other hand, significant differences in allele frequencies were detected in the comparison of Mexican healthy subjects with other populations. Whether these differences are fortuitous or related to diverse genetic backgrounds remains to be elucidated.

We report a boy with Down syndrome and leukemia who acquired uniparental isodisomy of chromosome 7q as a secondary chromosomal change during recurrence of the disease. His karyotype before therapy was 46,XY,der(1)t(1;1)(p36;q32),−7,+21c[17]/46,idem,del(9)(p22)[10], whereas at recurrence it was 46,XY,der(1)t(1;1)(p36;q32,−7,der(7)(qter→p22∼pter::q10→qter),del(9)(p22),+21c[13]/47,XY,+21c[2]. By using polymerase chain reaction amplification of D7S493 and D7S527 markers, we identified the loss of the maternal chromosome 7 with a consequent paternal isodisomy in the clone with dup7q. This rearrangement could be implicated in the progression of the disease by causing (1) nullisomy for a gene or genes located on 7p22→pter, (2) functional double doses of exclusively paternal expressed genes, and (3) restoration of the effects produced by haploinsufficiency of biparental expressed genes.

Introduccion. Las distrofinopatias son trastornos geneticos ligados al cromosoma X causados por mutaciones en el gen DMD. Las pruebas geneticas son de suma importancia para la gestion y el asesoramiento genetico de estas enfermedades. Sin embargo, la complejidad del gen DMD es un desafio para el diagnostico. Objetivo. Describir los avances recientes en el diagnostico de distrofinopatias, despues de 20 anos de los primeros ensayos moleculares para la deteccion genetica de estas enfermedades. Desarrollo. En la actualidad, se han desarrollado una variedad de estrategias, como la deteccion de mutaciones automatizada, los metodos basados en celulas y la haplotipificacion de alto rendimiento, para facilitar el diagnostico de distrofinopatias, la deteccion de portadoras, el diagnostico prenatal y preimplantacional. Conclusion. Las nuevas tecnologias han mejorado la deteccion temprana y el manejo optimo de distrofinopatias, y han establecido la base para la medicina molecular en el futuro. Los avances mas importantes en el diagnostico de distrofinopatias se revisan en este documento.