XRCC1 R194W and R399Q Polymorphisms and Colorectal Cancer Risk in a Northeastern Mexican Population.

Colorectal cancer (CRC) is one of the most common cancers worldwide. Its etiopathogenesis is complex, mainly influenced by genetic instability caused by the accumulation of mutations. The XRCC1 gene, which is involved in DNA repair, has been associated with CRC through the R194W (C194T) and R399Q (G399A) polymorphisms, but the results are inconsistent. Here, we analyzed the association of these polymorphisms with sporadic CRC in a northeastern Mexican population, including 155 male CRC patients and 155 male controls. Genotyping was performed using the RFLP method. An association with CRC was found for the 399A allele (G vs A; OR = 1.48 (1.03-2.13), P=0.034) and for the 399AA genotype in a codominant model (AA vs GG; OR = 3.11 (1.06-9.10), P=0.031). In contrast, there were no significant differences between CRC patients and controls for the C194T polymorphism (C vs T; OR = 0.82 (0.52-1.31), P=0.41). These results are consistent with many similar studies, but further research is needed to verify whether the XRCC1 R194W and R399Q polymorphisms play a role in CRC etiology. The functional significance of these polymorphisms is unclear, but some studies suggest that they influence DNA repair capacity and, thus, cancer risk.

Chromosomal instability in a patient with ring chromosome 14 syndrome: a case report.

BACKGROUND: Ring chromosome 14 syndrome is a rare disorder primarily marked by early-onset epilepsy, microcephaly, distinctive craniofacial features, hypotonia, intellectual disability, and delay in both development and language acquisition. CASE PRESENTATION: A 21-year-old woman with a history of epileptic seizures since the age of 1.5 years presented with distinctive craniofacial features, including a prominent and narrow forehead, sparse and short eyebrows, palpebral ptosis, horizontal palpebral fissures, a broad nasal bridge, a prominent nasal tip, a flat philtrum, hypertelorism, midfacial hypoplasia, horizontal labial fissures, a thin upper lip, crowded teeth, an ogival palate, retrognathia, and a wide neck. Additional physical abnormalities included kyphosis, lumbar scoliosis, pectus carinatum, cubitus valgus, thenar and hypothenar hypoplasia, bilateral hallux valgus, shortening of the Achilles tendon on the left foot, and hypoplasia of the labia minora. Chromosomal analysis identified a ring 14 chromosome with breakpoints in p11 and q32.33. An aCGH study revealed a ~ 1.7 Mb deletion on chromosome 14qter, encompassing 23 genes. Genomic instability was evidenced by the presence of micronuclei and aneuploidies involving the ring and other chromosomes. CONCLUSION: The clinical features of our patient closely resembled those observed in other individuals with ring chromosome 14 syndrome. The most important point was that we were able to verify an instability of the r(14) chromosome, mainly involving anaphasic lags and its exclusion from the nucleus in the form of a micronucleus.

Novel TINF2 gene mutation in dyskeratosis congenita with extremely short telomeres: A case report.

BACKGROUND: Dyskeratosis congenita is a rare disease characterized by bone marrow failure and a clinical triad of oral leukoplakia, nail dystrophy, and abnormal skin pigmentation. The genetics of dyskeratosis congenita include mutations in genes involved in telomere maintenance, including TINF2. CASE SUMMARY: Here, we report a female patient who presented thrombocytopenia, anemia, reticulate hyperpigmentation, dystrophy in fingernails and toenails, and leukoplakia on the tongue. A histopathological study of the skin showed dyskeratocytes; however, a bone marrow biopsy revealed normal cell morphology. The patient was diagnosed with dyskeratosis congenita, but her family history did not reveal significant antecedents. Whole-exome sequencing showed a novel heterozygous punctual mutation in exon 6 from the TINF2 gene, namely, NM_001099274.1:c.854delp.(Val285Alafs*32). An analysis of telomere length showed short telomeres relative to the patient's age. CONCLUSION: The disease in this patient was caused by a germline novel mutation of TINF2 in one of her parents.

Cytogenomic characterization of a de novo 4q34.1 deletion in a girl with mild dysmorphic features and a coagulation disorder.

BACKGROUND: 4q deletion syndrome is a rare chromosomal disorder that mostly arises de novo. The syndrome is characterized by craniofacial dysmorphism, digital abnormalities, skeletal alterations, heart malformations, developmental delay, growth retardation, Pierre Robin sequence, autistic spectrum and attention deficit-hyperactivity disorder, although not every patient shows the same features. Array comparative genomic hybridization (aCGH) use improves the detection of tiny chromosomal deletions and allows for a better understanding of genotype-phenotype correlations in affected patients. We report the case of a 6-year-old female patient showing mild dysmorphic features, mild mental disabilities and a coagulation disorder as a consequence of a de novo del(4)(q34.1) characterized by aCGH. CASE PRESENTATION: A 6-year-old female patient exhibited special craniofacial features, such as backward-rotated ears, upslanted palpebral fissures, broad nasal bridges, anteverted nares, broad nasal alae, smooth philtrums, smooth nasolabial folds, thin lips, horizontal labial commissures, and retrognathia. In the oral cavity, maxillary deformation, a high arched palate, agenesis of both mandibular canines and fusion of two mandibular incisors were observed. She also displayed bilateral implantation of the proximal thumbs, widely spaced nipples, dorsal kyphosis, hyperlordosis, and clitoral hypertrophy. In addition, the patient presented with coagulopathy, psychomotor delay, attention deficit-hyperactivity disorder, and mild mental disability. A chromosomal study showed the karyotype 46,XX,del(4)(q34.1), while an aCGH analysis revealed an 18.9 Mb deletion of a chromosome 4q subtelomeric region spanning 93 known genes. CONCLUSION: The clinical manifestations of this patient were similar to those reported in other individuals with 4q deletion syndrome. Although most of the patients with a 4q34 terminal deletion share similarities, variations in phenotype are also common. In general, clinical effects of chromosomal deletion syndromes depend on the length of the deleted chromosomal segment and, consequently, on the number of lost genes; however, in all of these syndromes, there is no simple correlation between the phenotype and the chromosomal region involved, particularly in cases of 4q deletion.

Report of trisomy 2q34-qter and monosomy 4q35.2-qter in a child with mild dysmorphic syndrome and karyotype 46,XY,der(4)t(2;4)(q34;q35.2)pat.

BACKGROUND: Concomitant trisomy 2q3 and monosomy 4q3 have been rarely reported. Pure trisomy 2q3 has been associated with microcephaly, hypertelorism, low-set ears, micrognathia, visceral abnormalities, and growth retardation. Monosomy 4q3 includes a wide variety of dysmorphic features such an abnormal skull shape, hypertelorism, Pierre Robin sequence, short nose with abnormal bridge, fifth finger clinodactyly, congenital heart, and genitourinary defects, in addition to intellectual disability, developmental delay, and hypotonia, but more distal deletions involving 4q34-qter may result in milder phenotypes. Here, we present a child with a mild dysmorphic syndrome, resulted of a duplication 2q34-qter and a deletion 4q35.2-qter inherited of his father. CASE PRESENTATION: We report a child, who at birth presented hypotonia, dysmorphism, and bilateral cryptorchidism. At 2 years and 9 month of age he showed brachycephaly, narrow forehead, bilateral frontoparietal hypertrichosis, down slanting palpebral fissures, sparse eyebrows, sparse short eyelashes, hypertelorism, depressed nasal root, broad nasal bridge, bulbous nasal tip, prominent colummela, broad nasal ala, smooth filtrum, high arched palate, thin upper lips, and ears rotated backwards. He also showed telethelia, hypertrichosis from dorsal to the sacral region, hands with clinodactyly and hypoplasia of the terminal phalanx of the fifth finger, and broad thumbs, broad first toes, and right cryptorchidism. A chromosomal study revealed a karyotype 46,XY,der(4)t(2;4)(q34;q35.2), while an array comparative genomic hybridization showed a 31.12 Mb duplication of the chromosome 2q34-q37.3 and a 1.49 Mb deletion in the chromosome 4q35.2. CONCLUSIONS: To our knowledge, only four families with translocation t(2;4) have been reported, two of them involving t(2q;4q), but the breakpoints involved in our patient have not been previously observed. The genomic imbalance in this patient was a duplication of 318 genes of the region 2q34-q37.3 and a deletion of 7 genes of 4q35.2. We discuss difficulty to assign specific congenital abnormalities to these duplicated/deleted regions and include some cases with terminal deletions of 4q with normal or just mildly detectable phenotypic effects.

BCR/ABL1 Transcripts in Healthy Individuals: A Comparative Analysis Between First-Degree Relatives of Patients with Chronic Myelogenous Leukemia and Subjects without Antecedents of the Disease.

BCR/ABL1 transcripts, the molecular hallmarks of chronic myeloid leukemia (CML), have been detected in peripheral blood from healthy individuals. Although CML is a sporadic disease, familial occurrence has been reported. This raises the question of whether there is a hereditary factor related to the etiology of CML. Our aim is to compare the BCR/ABL1 e13a2 and e14a2 transcript frequency in healthy first-degree relatives of families with CML versus individuals from families without CML antecedents. Ninety-eight healthy individuals, sorted into two groups, were studied: a group consisting of 46 first-degree relatives from families having a CML affected, and another with 52 healthy individuals from families without CML antecedents. BCR/ABL1 e13a2 and e14a2 transcripts were detected in mRNA isolated from peripheral blood leukocytes. We observed 28 of 98 individuals positive for at least one BCR/ABL1 transcript: e14a2 was detected in 22, e13a2 in 4, and co-expression was observed in 2 subjects. The positivity rate in relatives of CML cases was 33%, whereas individuals without CML antecedents had a 25% positivity rate, showing no statistical difference. Our results corroborate the presence of e13a2 and e14a2 BCR/ABL1 transcripts in the peripheral blood of healthy individuals, but has not a found familial factor related to the etiology of this rearrangement.

Association of the MTHFR 677C>T Polymorphism with Obesity and Biochemical Variables in a Young Population of Mexico.

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms have been associated with overweight people and obesity. The goal of this study was to investigate the relationship of the MTHFR 677C>T polymorphism with obesity and biochemical variables in young individuals of Mexico. METHODS: A total of 316 young individuals were included in the study, 172 with normal weight (NW) and 144 with over weight/obesity. Body mass index (BMI) was classified as NW, overweight, and obesity. Also, waist circumference was measured. Moreover, glucose, total cholesterol, and triglycerides were determined. Genotyping for MTHFR 677C>T polymorphism was performed by the PCR-RFLP method. RESULTS: There was no difference in the distribution of the MTHFR 677C>T polymorphism between individuals with NW and overweight/obesity; neither when they were divided by overweight vs NW, nor when we contrasted obese vs NW. However, an analysis stratified by gender showed a significant protector effect of the TT genotype against obesity in males and elevated waist circumference in females. Also, overweight/obese individuals with TT genotype had less risk of high cholesterol or triglycerides than overweight/obese subjects with the other genotypes. CONCLUSIONS: These results suggest that the MTHFR 677T polymorphism might not be a risk factor for being overweight/obesity. Rather, on the basis of our results, this variant could be a protector effect. However, further large-scale population-based studies are still necessary to clarify the role of the MTHFR 677C>T polymorphism in overweight, obesity, and lipid profile level.

Chromosomal abnormalities in couples with reproductive disorders.

AIM: To determine the prevalence of chromosomal abnormalities in couples with reproductive disorders. METHODS: A retrospective study was performed in 939 Mexican couples with reproductive disorders (542 with recurrent fetal loss, 356 with malformed/stillborn children, and 41 with sterility) whose karyotype was established on GTG-banded metaphases. RESULTS: A chromosomal aberration was detected in one partner of 52 couples, including a double translocation carrier; therefore, the prevalence of chromosomally abnormal couples was 5.5%; 31 couples with recurrent fetal loss (31/542, 5.7%), 15 with malformed/stillborn children (15/356, 4.2%), and 6 with sterility (6/41, 14.6%). There were 43 couples with structural rearrangements (29 reciprocal translocations, 10 robertsonian translocations, 2 inversions, 1 insertion, and 1 ring) and 9 with gonosomal aneuploidies. The affected partner was female in 28 (53.8%) and male in 24 (46.2%) couples. In addition, 17 couples (1.8%) with the structural variant inversion 9qh were detected. CONCLUSION: The prevalence of chromosomal abnormalities found in our sample is consistent with figures described in several populations around the world.

Prevalence of the BCR/ABL1 transcripts in Mexican patients with chronic myelogenous leukemia.

RT-PCR studies in 93 patients with chronic myelogenous leukemia from the Mexican West were done in order to know the proportion of b2a2 and b3a2 BCR/ABL1 transcripts. Forty-five patients showed the b3a2 transcript (48%), 37 (40%) displayed the b2a2 and in 11 cases (12%) both transcripts were detected. Statistical analyses showed that these figures are in accordance with two of three similar studies realized in Mexican population. Moreover, significant differences were found among Mexican people and patients from other countries, namely Ecuador, England, Italy, Poland, Japan, and Thailand. Ecuadorian patients showed differences with all the populations analyzed. These variations could be due to a different genetic background.

Genetic Epidemiology of Type 2 Diabetes in Mexican Mestizos.

There are currently about 415 million people with diabetes worldwide, a figure likely to increase to 642 million by 2040. In 2015, Mexico was the second Latin American country and sixth in the world in prevalence of this disorder with nearly 11.5 million of patients. Type 2 diabetes (T2D) is the main kind of diabetes and its etiology is complex with environmental and genetic factors involved. Indeed, polymorphisms in several genes have been associated with this disease worldwide. To estimate the genetic epidemiology of T2D in Mexican mestizos a systematic bibliographic search of published articles through PubMed, Scopus, Google Scholar, and Web of Science was conducted. Just case-control studies of candidate genes about T2D in Mexican mestizo inhabitants were included. Nineteen studies that met the inclusion criteria were found. In total, 68 polymorphisms of 41 genes were assessed; 26 of them were associated with T2D risk, which were located in ABCA1, ADRB3, CAPN10, CDC123/CAMK1D, CDKAL1, CDKN2A/2B, CRP, ELMO1, FTO, HHEX, IGF2BP2, IRS1, JAZF1, KCNQ1, LOC387761, LTA, NXPH1, SIRT1, SLC30A8, TCF7L2, and TNF-α genes. Overall, 21 of the 41 analyzed genes were associated with T2D in Mexican mestizos. Such a genetic heterogeneity compares with findings in other ethnic groups.

Corrigendum to "Association of Nuclear Factor-Erythroid 2-Related Factor 2, Thioredoxin Interacting Protein, and Heme Oxygenase-1 Gene Polymorphisms with Diabetes and Obesity in Mexican Patients".

[This corrects the article DOI: 10.1155/2016/7367641.].

Polymorphisms of the XRCC1 gene and breast cancer risk in the Mexican population.

The purpose of this case-control study was to evaluate the association of XRCC1 Arg194Trp and Arg399Gln polymorphisms with susceptibility to breast cancer (BC) in a Mexican population. We analysed DNA samples from 345 BC patients and 352 control subjects by polymerase chain reaction-restriction fragment length polymorphism. The frequency of the 399Gln allele was 23% in controls and 29% in patients [OR 1.38 (1.08-1.76); p = 0.01]; genotypes in controls were 60, 36, and 4% for Arg/Arg, Arg/Gln, and Gln/Gln, respectively, while in patients they were 53, 36, and 11% [OR 2.71 (1.44-5.10); p = 0.0015 for the Gln/Gln genotype]. Regarding the Arg194Trp polymorphism, the frequency of Trp allele was 15% in controls and 16% in patients [OR 1.09 (0.82-1.46); p = 0.54]; the genotype frequencies in controls were 74, 23, and 3% for Arg/Arg, Arg/Trp and Trp/Trp, respectively, while in patients these were 73, 23, and 4% [OR 1.41 (0.64-3.14); p = 0.39 for the Trp/Trp genotype]. Allele frequencies were consistent with Hardy-Weinberg equilibrium (p = 0.20 for Arg194Trp and p = 0.54 for Arg399Gln). Our results indicate that the 399Gln polymorphism is associated with an increased risk of BC. Additionally, we found that some covariates increase the risk of BC in Mexican women; namely, antecedent of abortions [OR 3.69 (2.17-6.27); p < 0.001], not breastfeeding [OR 2.46 (1.45-4.18); p = 0.001], family history of BC [OR 15.9 (5.09-50.23); p < 0.001], other type of family cancer [OR 31.5 (12.5-79.3); p < 0.001], alcoholism [OR 17.7 (5.2-60.42); p < 0.001], type 2 diabetes mellitus [OR 2.28 (1.26-4.10); p = 0.007], and contraceptive use [OR 2.28 (1.26-4.10); p < 0.001].

Secondary chromosomal changes in 34 Philadelphia-chromosome-positive chronic myelocytic leukemia patients from the Mexican West.

The clonal evolution in t(9;22)-positive chronic myelocytic leukemia (CML) is well established. Four major changes occur in more than 70% of patients: +8, i(17q), +19, and an extra Philadelphia chromosome. The frequencies of secondary chromosomal changes in 34 patients from the states of Jalisco, Nayarit, Michoacán, and Colima (the Mexican West) with Philadelphia-chromosome-positive CML were assessed. The most frequent abnormalities were tetraploidy (12 cases); +8, inv(3)(q21q26), and octoploidy (3 cases each); and +der(22)(2 cases). Some translocations not previously associated with CML were observed, such as t(2;7)(p12;q36), t(3;6)(q26;p25), t(3;17)(q26;p13), and t(6;17)(q21;q23 approximately q25). Significant differences were found for +8 with respect to population results from Japan and from southern, eastern, and western Europe; for i(17)(q10) from eastern Europe; for +19 from Japan and western Europe; and for +der(22) from Japan, southern Europe, and western Europe. Although polyploidy could result from endomitosis, there is no direct evidence that the BCR/ABL protein influences such a process; however, protein kinases such as MAPK, which are involved in endomitosis, are activated by the BCR/ABL protein, and so the BCR/ABL protein could promote endomitosis through the MAPK pathway.

A t(1;9)(q23.3 approximately q25;q34) affecting the ABL1 gene in a biphenotypic leukemia.

Recurring chromosome translocations, which are found in leukemia, can result in the inappropriate expression of oncogenes or in the formation of chimeric genes that code for structurally and functionally abnormal proteins. The chromosomal t(1;9)(q23.3 approximately q25;q34) was found in a patient with biphenotypic leukemia. Fluorescence in situ hybridization (FISH) analysis revealed that the break on chromosome 9 occurred in the ABL1 gene. The breakpoint on chromosome 1 occurred distal to the PBX1 gene at 1q23.3, as shown by FISH using BAC RP11-503N16 and RP11-403P14, which flank the PBX1 locus; hence, the ABL1 gene can be fused with another gene distal to PBX1 gene.

Association of the SLC6A4 gene 5HTTLPR polymorphism and ADHD with epilepsy, gestational diabetes, and parental substance abuse in Mexican mestizo children / Asociación del polimorfismo 5HTTLPR del gen SLC6A4 y TDAH con epilepsia, diabetes gestacional y adicción de los padres en niños mestizos mexicanos

Abstract Introduction Attention deficit hyperactivity disorder (ADHD) is one of the most common neuropsychiatric conditions in childhood and a multifactorial condition attributable to genetic and/or environmental influence. Allelic variants in the serotonin transporter gene (SLC6A4) have been associated to lower transcriptional efficiency, changes in serotonin concentration in several brain regions, and ADHD development. Objective To identify the association between the SLC6A4 alleles and ADHD diagnosis and risk factor phenotypes in children from a Mexican mestizo population. Method In this study, 134 unrelated children were included and evaluated for ADHD, genotypification for the 5HTTLPR polymorphism, and identification of multiple phenotypes from their clinical records and family background for association analysis. Results The following distribution of genotypes was observed: 23% SS, 49% SL, and 28% LL. From the phenotypes evaluated in the present study, gestational diabetes mellitus (p = .045), history of epilepsy (p = .047), and parental substance abuse (p = .033) showed an association with ADHD development in regression analysis along with the S variant. Discussion and conclusion Results suggest that interaction of the S allele and some of the phenotypes analyzed may play a relevant role in the development of ADHD in the studied population.

Resumen Introducción El trastorno por déficit de atención e hiperactividad (TDAH) es uno de los padecimientos neuropsiquiátricos más comunes en la infancia. Como su naturaleza es multifactorial, es atribuible a influencias genéticas y/o ambientales. Las variantes alélicas del gen transportador de serotonina (SLC6A4) se han asociado previamente con cambios en los niveles de serotonina en algunas regiones cerebrales, así como con el desarrollo de TDAH. Objetivo Identificar la posible asociación entre los alelos del gen SLC6A4 y el diagnóstico de TDAH, así como factores de riesgo en niños mestizos mexicanos. Método En el presente estudio se incluyeron 134 niños, los cuales fueron evaluados para TDAH, genotipificación del polimorfismo 5HTTLPR e identificación de múltiples fenotipos en su historia clínica y antecedentes familiares para su análisis de asociación estadística. Resultados Se mostró la siguiente distribución de genotipos: 23% SS, 49% SL y 28% LL. En un modelo de regresión, los fenotipos de diabetes mellitus gestacional (p = .045), historia de epilepsia (p = .047) y el abuso de sustancias de los padres (p = .033) mostraron asociación con la variante S y el desarrollo de TDAH. Discusión y conclusión El presente estudio sugiere que el alelo S en conjunto con algunos fenotipos puede cumplir un papel importante en el desarrollo de TDAH en nuestra población.

MDR1 C3435T polymorphism in Mexican children with acute lymphoblastic leukemia and in healthy individuals.

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.