Genetic Variants Associated with Suicide Risk in the Mexican Population: A Systematic Literature Review.

Suicide is defined as the action of harming oneself with the intention of dying. It is estimated that worldwide, one person dies by suicide every 40 s, making it a major health problem. Studies in families have suggested that suicide has a genetic component, so the search for genetic variants associated with suicidal behavior could be useful as potential biomarkers to identify people at risk of suicide. In Mexico, some studies of gene variants related to neurotransmission and other important pathways have been carried out and potential association of variants located in the following genes has been suggested: SLC6A4, SAT-1, TPH-2, ANKK1, GSHR, SCARA50, RGS10, STK33, COMT, and FKBP5. This systematic review shows the genetic studies conducted on the Mexican population. This article contributes by compiling the existing information on genetic variants and genes associated with suicidal behavior, in the future could be used as potential biomarkers to identify people at risk of suicide.

Association of rs4711998 of IL-17A, rs2275913 of IL-17A and rs763780 IL-17F gene polymorphisms with non-segmental vitiligo in a Mexican population.

Vitiligo is the most common depigmenting disease characterized by achromic macules due to selective loss of melanocytes. The pathogenesis remains poorly elucidated, and multiple hypotheses exist regarding its pathogenesis. Evidence suggests that stress on melanocytes can result in activation of the immune system, and involvement of both activated cluster of differentiation (CD8+) cytotoxic and CD4+ T cells in the dysfunction, depigmentation, and apoptosis of melanocytes. Recent studies show that the interleukin 17 (IL-17) axis plays a central role in the pathogenesis of the disease. IL-17 is an important regulatory effector cytokine in this pathway. The aim of this study was to evaluate the association of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) with vitiligo in a Northeastern Mexican population. This was a case-control study and included 116 patients with vitiligo and 116 control subjects. Genotype characterization of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A p ≤ 0.05 was considered significant. It was observed that the combination of the genotypes GG/GA for IL-17F rs763780 (7488A/G) was associated with an increased risk for the development of vitiligo (OR 2.0943, 95% Cl 1.2375-3.5445, p = 0.0056). Regarding IL-17A rs4711998 (-832A/G) and IL-17A rs2275913 (-197G/A) genotyping, no association with vitiligo development was found. In conclusion, the SNP rs763780 in the IL-17F gene appears to be a risk factor for vitiligo development in this Mexican population and it may be useful in future studies, especially for the development of new therapies.

Recent applications of cell-penetrating peptide guidance of nanosystems in breast and prostate cancer.

Cell-penetrating peptides (CPPs) are small peptides from natural sources or designed from other protein sequences that can penetrate cell membranes. This property has been used in biomedicine to add them to biomolecules to improve their capacity for cell internalization and as a guidance tool for specific cell types. CPPs have been shown to enhance cellular uptake in vitro and in vivo, improving the efficacy of anticancer drugs such as doxorubicin and paclitaxel, while also limiting their cytotoxic effects on healthy cells and tissues. The current study reviews the internalization and major therapeutic results achieved from the functionalization of nanosystems with CPPs for guidance into breast and prostate cancer cells in vitro and in vivo. In addition, the practical results obtained are specifically discussed for use as a starting point for scientists looking to begin research in this field.

Updates and new medical treatments for vitiligo (Review).

Vitiligo is a multifactorial disease characterized by the loss of skin pigment, which results in achromic macules and patches. There are currently several medical treatments available, which aim to arrest progression and induce skin repigmentation. These treatments alone or combined have exhibited varying degrees of pigmentation, and the majority are safe and effective. All therapies for vitiligo are limited, and no known treatment can consistently produce repigmentation in all patients. Individualized treatment is appropriate according to the location, clinical presentation and the presence of disease activity. The present review summarizes the medical treatments available for vitiligo: Systemic and topic pharmacological therapies, physical and depigmentation treatments. Several treatments are still underway and have not yet been approved. However, due to the promising preliminary results, these are also mentioned in the present review.

Analysis of HPV Integrations in Mexican Pre-Tumoral Cervical Lesions Reveal Centromere-Enriched Breakpoints and Abundant Unspecific HPV Regions.

Human papillomavirus (HPV) DNA integration is a crucial event in cervical carcinogenesis. However, scarce studies have focused on studying HPV integration (HPVint) in early-stage cervical lesions. Using HPV capture followed by sequencing, we investigated HPVint in pre-tumor cervical lesions. Employing a novel pipeline, we analyzed reads containing direct evidence of the integration breakpoint. We observed multiple HPV infections in most of the samples (92%) with a median integration rate of 0.06% relative to HPV mapped reads corresponding to two or more sequence breakages. Unlike cancer studies, most integrations events were unique (supported by one read), consistent with the lack of clonal selection. Congruent to other studies, we found that breakpoints could occur, practically, in any part of the viral genome. We noted that L1 had a higher frequency of rupture integration (25%). Based on host genome integration frequencies, we found previously reported integration sites in cancer for genes like FHIT, CSMD1, and LRP1B and putatively many new ones such as those exemplified in CSMD3, ROBO2, and SETD3. Similar host integrations regions and genes were observed in diverse HPV types within many genes and even equivalent integration positions in different samples and HPV types. Interestingly, we noted an enrichment of integrations in most centromeres, suggesting a possible mechanism where HPV exploits this structural machinery to facilitate integration. Supported by previous findings, overall, our analysis provides novel information and insights about HPVint.

Novel immunological and genetic factors associated with vitiligo: A review.

Vitiligo is a skin disorder characterized by depigmentation of the skin due to a lack of melanin. This condition affects men and woman of all ages and its incidence is not restricted by ethnicity or region. Vitiligo is a multifactorial disease, in which melanocytes, which serve important functions in skin pigmentation and immune processes, are impaired. There is sufficient evidence that immunological and genetic factors are primarily responsible for the destruction and dysfunction of melanocytes. Therefore, genetic DNA sequence variants that participate in skin homeostasis, pigmentation and immune response regulation, as well as altered expression patterns, may contribute to the risk of developing vitiligo. The current review presented an overview of the mechanism of pigmentation and of currently known factors involved in depigmentation, as well as the classification, epidemiology, associated comorbidities, risk factors, immunopathogenesis and several genetic and molecular changes associated with vitiligo.

Steroid 5 alpha-reductase 2 enzyme variants, biomass exposure and tobacco use in Mexican patients with prostate cancer.

The presence of the genetic variants of the steroid 5-alpha reductase 2 enzyme, which is encoded by the SRD5A2 gene, has been associated with an increased risk of developing prostate cancer among certain ethnic groups. However, these molecular studies have not been conducted on the Mexican population. The analysis of the genetic variants, rs9282858 and rs523349, was performed in 101 males with prostate cancer and 100 healthy controls classified as males without prostate abnormalities (n=60) and males with benign prostatic hyperplasia (n=40), to identify a probable association with this cancer type in the Northeast Mexican population. An association was identified between prostate cancer and biomass exposure [P=0.012; odds ratio (OR), 2.89; confidence interval (CI)=1.21-6.88] and tobacco use (P=0.028; OR=1.88; CI=1.07-3.31), while no association was observed between cancer development and the rs9282858 variant, or between a protective effect and the rs523349 variant. Notably, an association was identified between rs523349 and biomass exposure (P=0.013, OR=3.17; CI=1.23-8.17 for the G risk allele, and OR=0.32, CI=0.12-0.81 for the C protective allele) using the dominant genetic model. To the best of our knowledge, the present study was the first of its type to investigate the Mexican population with prostate cancer.

CTLA4 +49AG (rs231775) and CT60 (rs3087243) gene variants are not associated with alopecia areata in a Mexican population from Monterrey Mexico

Abstract Background: Alopecia areata is an autoimmune disease that produces non-scarring hair loss around the body. Gene variants of the cytotoxic T-lymphocyte antigen 4 (CTLA4) gene, a negative regulator of T-cell response, have been associated with a predisposition to autoimmune diseases in different populations; however, the involvement of these genetic variants in the development of AA is controversial. Objective: The present study evaluated the potential association of two CTLA4 gene variants with alopecia areata in a Mexican population. Methods: We genotyped +49AG (rs231775) and CT60 (rs3087243) variants in 50 AA patients and 100 healthy control participants through PCR-RFLP. Results: No statistical difference was observed for either of the gene variants regarding allele or genotype frequencies between AA patients and the controls when the parameters of family/personal history of autoimmune diseases or gender were considered (p > 0.05). Study limitations: Small sample size of patients and the data were obtained from Northeast Mexico population. Conclusion: The genetic variants rs231775 and rs3087243 of the CTLA4 gene are not a risk factor for the development of alopecia areata in the analyzed Mexican population.

CTLA4 +49AG (rs231775) and CT60 (rs3087243) gene variants are not associated with alopecia areata in a Mexican population from Monterrey Mexico.

BACKGROUND: Alopecia areata is an autoimmune disease that produces non-scarring hair loss around the body. Gene variants of the cytotoxic T-lymphocyte antigen 4 (CTLA4) gene, a negative regulator of T-cell response, have been associated with a predisposition to autoimmune diseases in different populations; however, the involvement of these genetic variants in the development of AA is controversial. OBJECTIVE: The present study evaluated the potential association of two CTLA4 gene variants with alopecia areata in a Mexican population. METHODS: We genotyped +49AG (rs231775) and CT60 (rs3087243) variants in 50 AA patients and 100 healthy control participants through PCR-RFLP. RESULTS: No statistical difference was observed for either of the gene variants regarding allele or genotype frequencies between AA patients and the controls when the parameters of family/personal history of autoimmune diseases or gender were considered (p>0.05). STUDY LIMITATIONS: Small sample size of patients and the data were obtained from Northeast Mexico population. CONCLUSION: The genetic variants rs231775 and rs3087243 of the CTLA4 gene are not a risk factor for the development of alopecia areata in the analyzed Mexican population.

Evaluation of skin expression profiles of patients with vitiligo treated with narrow-band UVB therapy by targeted RNA-seq

Abstract: Background: Vitiligo is characterized by a lack of pigmentation in the skin. To date, there are no studies that analyze the changes in gene expression in the skin of vitiligo patients in response to narrow-band ultraviolet B (nb-UVB) phototherapy treatment. Objective: Explore the usefulness of new generation RNA sequencing in the identification of gene expression changes in the skin of vitiligo patients treated with nb-UVB phototherapy. Methods: Four skin biopsies (4mm in diameter) were collected from 45 Mexican vitiligo vulgaris patients, 2 specimens before and 2 after treatment with nb-UVB phototherapy, obtained from pigmented and non-pigmented tissue. RNA extracted from the biopsies was analyzed using the Illumina TruSeq Targeted RNA Expression protocol to study the expression of genes that participate in pathways of skin homeostasis. The 2 groups were compared using Student's t-test and the Mann-Whitney U-test. Results: The expression analysis identified differences in 12 genes included in this study after comparing the samples obtained before and after treatment: 5 genes involved in skin pigmentation, 2 genes involved in apoptosis, 2 genes involved in cell survival, 2 genes involved in oxidative stress responses and 1 gene involved in signal transduction mechanisms (p<0.05). Study limitations: The small size of skin biopsies limits the amount of RNA obtained, the number of genes to be analyzed and the use of conventional techniques such as RT-qPCR. Conclusion: We demonstrated usefulness of new generation RNA sequencing in the identification of gene expression changes, in addition to identifying new targets in the study of vitiligo.

Evaluation of skin expression profiles of patients with vitiligo treated with narrow-band UVB therapy by targeted RNA-seq.

BACKGROUND: Vitiligo is characterized by a lack of pigmentation in the skin. To date, there are no studies that analyze the changes in gene expression in the skin of vitiligo patients in response to narrow-band ultraviolet B (nb-UVB) phototherapy treatment. OBJECTIVE: Explore the usefulness of new generation RNA sequencing in the identification of gene expression changes in the skin of vitiligo patients treated with nb-UVB phototherapy. METHODS: Four skin biopsies (4mm in diameter) were collected from 45 Mexican vitiligo vulgaris patients, 2 specimens before and 2 after treatment with nb-UVB phototherapy, obtained from pigmented and non-pigmented tissue. RNA extracted from the biopsies was analyzed using the Illumina TruSeq Targeted RNA Expression protocol to study the expression of genes that participate in pathways of skin homeostasis. The 2 groups were compared using Student's t-test and the Mann-Whitney U-test. RESULTS: The expression analysis identified differences in 12 genes included in this study after comparing the samples obtained before and after treatment: 5 genes involved in skin pigmentation, 2 genes involved in apoptosis, 2 genes involved in cell survival, 2 genes involved in oxidative stress responses and 1 gene involved in signal transduction mechanisms (p<0.05). STUDY LIMITATIONS: The small size of skin biopsies limits the amount of RNA obtained, the number of genes to be analyzed and the use of conventional techniques such as RT-qPCR. CONCLUSION: We demonstrated usefulness of new generation RNA sequencing in the identification of gene expression changes, in addition to identifying new targets in the study of vitiligo.

Genetic variants in KCNJ11, TCF7L2 and HNF4A are associated with type 2 diabetes, BMI and dyslipidemia in families of Northeastern Mexico: A pilot study.

The aim of the present study was to investigate whether genetic markers considered risk factors for metabolic syndromes, including dyslipidemia, obesity and type 2 diabetes mellitus (T2DM), can be applied to a Northeastern Mexican population. A total of 37 families were analyzed for 63 single nucleotide polymorphisms (SNPs), and the age, body mass index (BMI), glucose tolerance values and blood lipid levels, including those of cholesterol, low-density lipoprotein (LDL), very LDL (VLDL), high-density lipoprotein (HDL) and triglycerides were evaluated. Three genetic markers previously associated with metabolic syndromes were identified in the sample population, including KCNJ11, TCF7L2 and HNF4A. The KCNJ11 SNP rs5210 was associated with T2DM, the TCF7L2 SNP rs11196175 was associated with BMI and cholesterol and LDL levels, the TCF7L2 SNP rs12255372 was associated with BMI and HDL, VLDL and triglyceride levels, and the HNF4A SNP rs1885088 was associated with LDL levels (P<0.05).

Beta-2 Microglobulin in Whole Unstimulated Saliva Can Effectively Distinguish Between Sjögren's Syndrome and Non-Autoimmune Sicca Symptoms.

OBJECTIVES: This study aims to describe salivary beta-2 microglobulin (sB2M) levels in our setting and to assess the performance of sB2M for the diagnosis of Sjögren's syndrome (SS). PATIENTS AND METHODS: This cross-sectional, comparative study included 192 SS patients (2 males, 190 females; mean age 53.1 years; range 23 to 84 years) and 64 healthy controls (1 male, 63 females; mean age 46.9 years; range 21 to 82 years). Patients were divided into three groups as those with primary SS, secondary SS, and sicca non-Sjögren's syndrome (snSS). sB2M was measured by enzyme-linked immunosorbent assay in whole unstimulated saliva (ng/mL). Differences in sB2M were evaluated using the Kruskal-Wallis test. Receiver operating curves were generated to determine the performance of sB2M for distinguishing between SS and non-autoimmune snSS groups, and between SS group and healthy controls. RESULTS: The primary SS and secondary SS groups had a significantly higher concentration of sB2M than the other two groups. There was no significant difference in the concentration of sB2M between primary SS and secondary SS groups, and neither between snSS group and healthy controls. The receiver operating curve analysis for distinguishing SS and snSS showed an area under the curve of 0.661 (95% confidence interval 0.590-0.728, p=0.0001) with an optimal cutoff value of 0.582 ng/mL. Sensitivity, specificity, positive predictive value, and negative predictive value were 68.7%, 59.3%, 20.2%, and 92.7%, respectively. The reported prevalence of SS in Mexico was considered when calculating the last two values. CONCLUSION: In our setting, sB2M effectively distinguished between SS patients and non-autoimmune sicca symptoms. Including sB2M in our conventional diagnostic arsenal may assist in the evaluation of patients in whom SS is suspected; however, further studies are needed to clarify this hypothesis.

Assessment of biochemical parameters and characterization of TNFα -308G/A and PTPN22 +1858C/T gene polymorphisms in the risk of obesity in adolescents.

Obesity is currently considered an inflammatory condition associated with autoimmune diseases, suggesting a common origin. Among other factors, candidate genes may explain the development of this disease. Polymorphisms in the tumor necrosis factor α (TNFα) and lymphoid protein tyrosine phosphatase (PTPN22) genes lead to an increased risk to development of immune and inflammatory diseases. The aim of the present study was to analyze the biochemical parameters and the effect of the TNFα -308G/A and PTPN22 +1858C/T polymorphisms in the susceptibility of adolescents to obesity. A group of 253 adolescent subjects were recruited and classified as obese, overweight or normal weight according to their nutritional status. Anthropometric measurements, clinical and biochemical data were analyzed. DNA was extracted from peripheral blood samples by the phenol-chloroform method, and TNFα -308G/A and PTPN22 1858C/T polymorphisms were determined by polymerase chain reaction-restriction fragment length polymorphism assays. Clinical, genetic and biochemical parameters were analyzed to determine the existence of a possible association with the development of obesity. Statistically significant differences in body mass index, insulin, triglyceride levels and homeostatic model assessment for insulin resistance (HOMA-IR) index were observed among the three groups analyzed (P≤0.05). The studied polymorphisms did not confer a risk for developing obesity in the analyzed population (P>0.05); however, significantly low levels of insulin and decreased rates of HOMA-IR were observed in the 1858 CT genotype carriers of the PTPN22 gene. In conclusion, no association between the TNFα -308G/A and PTPN22 +1858C/T polymorphisms and the risk to development of obesity in the adolescent population analyzed was observed. However, the 1858 CT genotype of the PTPN22 gene was associated with variations of certain biochemical parameters analyzed.

Low-income status is an important risk factor in North East Mexican patients with cystic fibrosis.

BACKGROUND. Factors such as environment, income status, as well as access to proper healthcare influence the survival and quality of life of people affected by chronic diseases including cystic fibrosis (CF). Survival factors in Mexican patients with CF have not been reported before, even when it has been estimated that this disease could not be negligible in the Mexican population. OBJECTIVE. To compare the influence of the mutant allele ΔF508 and environmental factors on the survival of Mexican CF patients. MATERIAL AND METHODS. We collected epidemiological data of 40 patients molecularly tested between 1987 and 2008 in the Clínica de Fibrosis Quística from the Hospital Universitario of the Universidad Autónoma de Nuevo León in Northeastern México. Kaplan-Meier plots and survival statistics were estimated and compared. RESULTS. Survival analysis revealed statistical significance for low-income status (p = 3.13 x 10-6), cor pulmonale (p = 0.00169), severe pulmonary disease (p = 0.00136), and BMI ≤15 kg/m2 (p = 0.00678). Statistical significance was not observed for the predominant allele ΔF508 considering two (p = 0.992), one (p = 0.503) or no (p = 0.403) mutant allele. CONCLUSIONS. Low income status was the most detrimental factor; followed by cor pulmonale, severe pulmonary disease and BMI ≤ 15 kg/m2 for the survival in North East Mexican patients with CF. Carrying the ΔF508 allele did not influence survival.

Frequency of S and Z alleles for alpha-1-antitrypsin and tumor necrosis factor alpha -308 promoter polymorphism in northeastern Mexico.

Diseases characterized by airway inflammation, excessive secretion, and obstruction affect a substantial proportion of the population. Studies for understanding the mechanisms underlying these processes are focused on the initiation and maintenance of inflammation. Polymorphisms on DNA sequence of response mediators such as alpha-1-antitrypsin (AAT) and tumor necrosis factor (TNF) alpha have the capacity to influence presentation of diseases, affecting protein amount and/or functionality, and can be analyzed as disease modulators. The purpose of this study was to analyze AAT S and Z alleles and -308G/A TNF-alpha polymorphism on the northeast Mexico mestizo population to compare the influence of these genes in several diseases. DNA samples from 103 volunteers (healthy group) were tested for modifier gene variants by polymerase chain reaction-RFLP as follows: AAT gene for S and Z alleles and TNF-alpha promoter -308G/A (TNF1/TNF2) alleles. Allele frequency for S and TNF2 alleles were 1.5 and 2.4%, respectively, whereas the Z allele was not detected. This study shows low frequencies of the AAT S and TNF2 alleles, and the Z allele was not found. Correlation studies in the future will allow to determine if these alleles have some influence in the clinical presentation of diverse diseases in this group of people.