Brachybacterium conglomeratum Is Associated with Cervicovaginal Infections and Human Papilloma Virus in Cervical Disease of Mexican Female Patients.

Brachybacterium conglomeratum, traditionally considered an environmental bacterium, has recently garnered attention for its potential involvement in human health. While prior research hinted at its pathogenic role in humans, our study aims to determine its prevalence and associations in diverse clinical contexts. We examined vaginal swabs from three distinct patient groups: patients with low-grade squamous intraepithelial lesions (LSIL), patients with cervicovaginal infections, and patients with a history of precancerous lesions undergoing follow-up. B. conglomeratum was present in all three patient groups, with the highest prevalence observed in the LSIL group. Statistically significant associations were primarily identified in the LSIL group, where B. conglomeratum was present in 60% of cases. Notably, the LSIL group exhibited coinfections with multiple high-risk oncogenotypes of human papillomavirus (HPV), suggesting potential synergistic effects, and understanding these microbial relationships and their influence on viral persistence, particularly with HPV, holds promise for mitigating HPV-related carcinogenesis. Furthermore, Gardnerella vaginalis and Atopobium vaginae were frequently detected in this group, along with Ureaplasma parvum as the predominant sexually transmitted bacterium. In all cases, B. conglomeratum was found in association with these microorganisms rather than as a sole pathogen. This coexistence underscores the intricate microbial interactions within cervicovaginal infections and precancerous lesions. This study marks the first report of B. conglomeratum prevalence in women with these clinical conditions.

Metastatic breast tumors downregulate miR-145 regulating the hypoxia-induced vasculogenic mimicry.

Tumor cells grow in three-dimensional (3D) channels-like structures denoted as vasculogenic mimicry (VM), which provides a route for nutrients and oxygen acquisition. VM is activated by hypoxia and associated with metastasis and poor prognosis. MetastamiRs are microRNAs regulating metastasis, however, if they control VM in breast cancer remains poorly understood. The aim of this study was to evaluate the expression of VM-associated microRNAs in tumors of metastatic breast cancer patients. Firstly, we constructed microRNAs/mRNAs coregulation networks using expression data from TCGA databases. Dozens of microRNAs regulating genes involved in VM and metastasis were found. Of these, we selected 10 microRNAs for further characterization. The presence of VM in histological samples from patients with or without metastasis was evaluated using CD31-/PAS+ immunophenotyping. Remarkably, data showed that VM was significantly increased in tumors from patients with metastasis in comparison with no-metastatic group. Gene expression analysis indicated that miR-145, miR-142-3p, miR-31, miR-148a, miR-200b-3p and miR-526b were downregulated in primary tumors from patients with metastatic disease and positive for VM. Moreover, modulated microRNAs showed a predictive clinical value in overall survival in a cohort (n=1262) of breast cancer patients. Of these, we evaluated the role of miR-145 in formation of hypoxia-induced 3D channels-like using an in vitro model that recapitulates the early stages of VM. Data showed that miR-145 mimics was able to abolish the VM development in both metastatic Hs578t and MDA-MB-231 breast cancer cells. In conclusion, manipulation of miR-145 levels may represent a therapeutic approach in metastatic breast cancer patients that developed VM.

Helicobacter pylori Virulence Factors and Clarithromycin Resistance-Associated Mutations in Mexican Patients.

Persistent infection with Helicobacter pylori (H. pylori) is an important factor in gastric diseases. The vacA and cagA virulence factors of H. pylori contribute to the development of these diseases. Triple therapy containing clarithromycin has been used to eradicate this infection. Unfortunately, resistance to this antibiotic is the primary cause of treatment failure. This study aimed to determine the prevalence of clarithromycin resistance-associated mutations and to assess the relationship between virulence factors and Mexican patients infected with H. pylori. The cagA and vacA genotypes were determined by multiplex PCR. Furthermore, a qPCR was used to identify mutations of the 23S rRNA gene. This study reported a prevalence of 84.3% of H. pylori among patients with gastric diseases, and the vacA s1m1/cagA+ genotype was the most frequent (44.8%) in antrum and corpus. Analysis of the 23S rRNA gene revealed a 19.8% prevalence of clarithromycin resistance-associated mutations. The most prevalent mutations were A2143G (56%) and A2142C (25%). A significant association (p < 0.05) between the A2142G and the vacA s1m1/cagA+ genotype was detected. In conclusion, we report a high prevalence (>15%) of clarithromycin resistance-associated mutations, and we found an association between the genotypes of virulence factors and a mutation in the 23S rRNA gene.

Gut Microbiota Associated with Gestational Health Conditions in a Sample of Mexican Women.

Gestational diabetes (GD), pre-gestational diabetes (PD), and pre-eclampsia (PE) are morbidities affecting gestational health which have been associated with dysbiosis of the mother's gut microbiota. This study aimed to assess the extent of change in the gut microbiota diversity, short-chain fatty acids (SCFA) production, and fecal metabolites profile in a sample of Mexican women affected by these disorders. Fecal samples were collected from women with GD, PD, or PE in the third trimester of pregnancy, along with clinical and biochemical data. Gut microbiota was characterized by high-throughput DNA sequencing of V3-16S rRNA gene libraries; SCFA and metabolites were measured by High-Pressure Liquid Chromatography (HPLC) and (Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR MS), respectively, in extracts prepared from feces. Although the results for fecal microbiota did not show statistically significant differences in alfa diversity for GD, PD, and PE concerning controls, there was a difference in beta diversity for GD versus CO, and a high abundance of Proteobacteria, followed by Firmicutes and Bacteroidota among gestational health conditions. DESeq2 analysis revealed bacterial genera associated with each health condition; the Spearman's correlation analyses showed selected anthropometric, biochemical, dietary, and SCFA metadata associated with specific bacterial abundances, and although the HPLC did not show relevant differences in SCFA content among the studied groups, FT-ICR MS disclosed the presence of interesting metabolites of complex phenolic, valeric, arachidic, and caprylic acid nature. The major conclusion of our work is that GD, PD, and PE are associated with fecal bacterial microbiota profiles, with distinct predictive metagenomes.

Fluorescence-Linked Aptamer Assay for SARS-CoV-2 Spike-Protein: A Step-by-Step Performance Analysis in Clinical Samples.

The COVID-19 pandemic has been a main concern over the last two years and has become one of the most important crises in the history of human health. Today, there is still a need for affordable and reliable diagnostic tests for massive disease monitoring. Previously, a set of highly specific DNA-aptamers (C7/C9) binding to the SARS-CoV-2 Spike (S) protein were isolated but its performance in clinical samples remained to be tested. Here, 242 samples were collected through three different methods and subjected to florescence-linked aptamer assays (FLAA) based on C7/C9 aptamers through two readout protocols. Then, a step-by-step statistical approach which included agreement tests, proportion comparisons and binomial and multinomial logistic regressions was used to predict optimal conditions for the novel C7/C9 FLAA test. RTqPCR threshold cycles, symptoms onset and processing time were influential factors on FLAA test results. Naturally occurring mutations on S were also detected and analyzed. Aminoacidic substitutions D614G and T732A appeared relevant for aptamer recognition although further studies are necessary. The methodology presented here is the first step to determine the performance and diagnosis across a range of clinical contexts and it might serve as a base for a complete analysis applicable to other designs of new diagnostic tests.

Dual activation profile of monocytes is associated with protection in Mexican patients during SARS-CoV-2 disease.

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been one of the most catastrophic diseases observed in recent years. It has reported nearly 550 million cases worldwide, with more than 6.35 million deaths. In Mexico, an increased incidence and mortality of this disease were observed, where the immune response has been involved in the magnitude and severity. A critical version of the disease is accompanied by hyperinflammatory responses, with cytokine and defective cellular responses. A detailed understanding of the role of molecules and cells in the immune response during COVID-19 disease may help to generate effective protection mechanisms, improving those we already have. Here we analyzed blood samples obtained from patients at the Hospital Regional de Alta Especialidad de Ixtapaluca (HRAEI), Mexico, which were classified according to living guidance for clinical management of COVID-19 by the World Health Organization: asymptomatic, mild, severe, and critical disease. We observed increased interleukin (IL)-6 levels and a T-CD8+ and T-CD4+ cell reduction correlated with the critical disease version. Importantly, here, we described a significant reduction of CD11b+CD45highCD14low monocytes during severe disease, which displayed a non-classical profile, expressing IL-10, transforming growth factor (TGF)-ß, and indoleamine 2,3-dioxygenase (IDO)1 molecule. Moreover, CD11b+CD45highCD14low monocytes obtained from infected one-dose vaccinated patients (Pfizer® vaccine) who suffered minimal symptoms showed simultaneously a dual classical and no-classical profile expressing pro- and anti-inflammatory cytokines. These results suggest that blood monocytes expressing a dual pro- and anti-inflammatory profile might be a predictive marker for protection in the Mexican population during COVID-19 disease. KEY POINTS : • Exacerbated immune response is associated with COVID-19 severe disease. • Dual monocyte activation profile is crucial for predicting protection during COVID-19. • Vaccination is crucial to induce the dual activation profile in monocytes.

Vaccines Against COVID-19: A Review.

As a result of the COVID-19 pandemic, various joint efforts have been made to support the creation of vaccines. Different projects have been under development, of which some are in the clinical evaluation stage and others in are in phase III with positive results. The aim of this paper was to describe the current situation of the development and production of vaccines available to the population to facilitate future research and continue developing and proposing ideas for the benefit of the population. So, we carried out a systematic review using databases such as PubMed, ScienceDirect, SciELO, and MEDLINE, including keywords such as "vaccines," "COVID-19," and "SARS-CoV-2". We reviewed the development and production of the anti-COVID vaccine and its different platforms, the background leading to the massive development of these substances, and the most basic immune aspects for a better understanding of their physiological activity and the immune response in those who receive the vaccine. We also analyzed immunization effects in populations with any medical or physiological conditions (such as immunosuppression, people with comorbidities, and pregnancy), as well as the response to immunization with heterologous vaccines and the hybrid immunity (the combination of natural immunity to SARS-CoV-2 with immunity generated by the vaccine). Likewise, we address the current situation in Mexico and its role in managing the vaccination process against SARS-CoV-2 at the national and international levels. There are still many clinical and molecular aspects to be described, such as the duration of active immunity and the development of immunological memory, to mention some of the most important ones. However, due to the short time since the global vaccination roll-out and that it has been progressive (not counting children and people with medical conditions), it is premature to say whether a second vaccination schedule will be necessary for the near future. Thus, it is essential to continue with health measures.

THE BRANCHED-CHAIN AMINO ACID TRANSAMINASE 1 -23C/G POLYMORPHISM CONFERS PROTECTION AGAINST ACUTE CORONARY SYNDROME.

BACKGROUND: Previous studies have shown an association between polymorphisms of the BAT1-NF-κB inhibitor-like-1 (NFKBIL1)-LTA genomic region and susceptibility to myocardial infarction and acute coronary syndrome (ACS). OBJECTIVE: The objective of the study was to study the role of three polymorphisms in the BAT1, NFKBIL1, and LTA genes on the susceptibility or protection against ACS; we included a group of cases-controls from Central Mexico. METHODS: The BAT1 rs2239527C/G, NFKBIL1 rs2071592T/A, and LTA rs1800683G/A polymorphisms were genotyped using a 5' TaqMan assay in a group of 625 patients with ACS and 617 healthy controls. RESULTS: Under a recessive model, the BAT1 -23C/G (rs2239527) polymorphism showed an association with protection against ACS (odds ratio = 0.56, and p-corrected = 0.019). In contrast, the genotype and allele frequencies of the NFKBIL1 rs2071592T/A and LTA rs1800683G/A polymorphisms were similar between ACS patients and controls and no association was identified. CONCLUSION: Our data suggest an association between the BAT1 -23C/G polymorphism and protection against ACS in Mexican patients.

The branched-chain amino acid transaminase 1 -23c/g polymorphism confers protection against acute coronary syndrome

ABSTRACT Background: Previous studies have shown an association between polymorphisms of the BAT1-NF-κB inhibitor-like-1 (NFKBIL1)-LTA genomic region and susceptibility to myocardial infarction and acute coronary syndrome (ACS). Objective: The objective of the study was to study the role of three polymorphisms in the BAT1, NFKBIL1, and LTA genes on the susceptibility or protection against ACS; we included a group of cases-controls from Central Mexico. Methods: The BAT1 rs2239527C/G, NFKBIL1 rs2071592T/A, and LTA rs1800683G/A polymorphisms were genotyped using a 5' TaqMan assay in a group of 625 patients with ACS and 617 healthy controls. Results: Under a recessive model, the BAT1 -23C/G (rs2239527) polymorphism showed an association with protection against ACS (odds ratio = 0.56, and p-corrected = 0.019). In contrast, the genotype and allele frequencies of the NFKBIL1 rs2071592T/A and LTA rs1800683G/A polymorphisms were similar between ACS patients and controls and no association was identified. Conclusion: Our data suggest an association between the BAT1 -23C/G polymorphism and protection against ACS in Mexican patients.

Predictive polymorphisms for breast cancer in postmenopausal Mexican women.

CONTEXT: Several factors contribute to the increase in breast cancer (BC) incidence, such as lifetime exposure to estrogen, early menarche and older ages at first birth, menopause, and the increased prevalence of postmenopausal obesity. In fact, there is an association between an increased BC risk and elevated estrogen levels, which may be involved in carcinogenesis via the estrogen receptor alpha (ERα) encoded by the ESR1 gene. Interestingly, there is an antagonistic relationship between ERα and the aryl hydrocarbon receptor (AhR) in BC cells. AIMS: Herein, we explore the combined effects of the ESR1 (XbaI, PvuII) and AhR polymorphisms on BC development in Mexican women according to their menopausal status. SETTINGS AND DESIGN: Investigation was performed using a cases and controls design. SUBJECTS AND METHODS: In a group of 96 cases diagnosed with BC and 111 healthy women, the single-nucleotide polymorphisms ESR1 (XbaI, PvuII) and AhR gene were identified by qPCR. STATISTICAL ANALYSIS USED: Chi-square test or Fisher's exact test were used. Statistical analyses were conducted using the STATA statistical package (Version 10.1, STATA Corp., College Station, TX, USA). RESULTS: The G/G XbaI genotype was more prevalent in the cases than in the controls (P = 0.008). Moreover, Mexican women carrying the XbaI (wild type [WT]/G or G/G) ESR1 genotype have higher risk (12.26-fold) for developing postmenopausal BC than individuals carrying the WT/WT genotype. CONCLUSIONS: The presence of the G/G genotype of XbaI may be considered a susceptibility allele in Mexican women. Due to increased postmenopausal BC risk, the XbaI (WT/G or G/G) alleles may be used as a postmenopausal predictive factor for BC in Mexican women.

Tumor necrosis factor gene polymorphisms are associated with systemic lupus erythematosus susceptibility or lupus nephritis in Mexican patients.

The TNF -238G/A (rs361525) and -308G/A (rs1800629) polymorphisms have consistently been associated with systemic lupus erythematosus (SLE) in several populations; however, these findings have not been verified in all populations. Here, we aimed to examine whether the TNF -238G/A, -308G/A, -376G/A (rs1800750), and -1031T/C (rs1799964) polymorphisms confer SLE or lupus nephritis (LN) susceptibility in a Mexican population. Our study included 442 patients with SLE and 495 controls. For genotyping, we used the TaqMan 5' allele discrimination assay. The TNF -238G/A and -1031T/C polymorphisms were associated with SLE susceptibility (odds ratio (OR) 2.1, p = 0.0005 and OR 1.4, p = 0.003, respectively). Gender stratification showed a strong association between TNF -238G/A and SLE in women (OR 2.2, p = 0.00006), while TNF -1031T/C had an OR of 1.5 (p = 0.007). With regard to the TNF -376G/A polymorphism, this also showed association with SLE susceptibility (OR 1.95, p = 0.036) and LN (OR 3.5, p = 0.01). In conclusion, our study provides the first demonstration of association between the TNF -376G/A polymorphism and SLE and LN susceptibility. In addition, our study is the second documenting an association of TNF -1031T/C with SLE susceptibility. We also observed a strong association between TNF -238G/A and SLE susceptibility. The TNF 308G/A polymorphism was not associated with SLE or LN.

Low Proteolytic Clipping of Histone H3 in Cervical Cancer.

Chromatin in cervical cancer (CC) undergoes chemical and structural changes that alter the expression pattern of genes. Recently, a potential mechanism, which regulates gene expression at transcriptional levels is the proteolytic clipping of histone H3. However, until now this process in CC has not been reported. Using HeLa cells as a model of CC and human samples from patients with CC, we identify that the H3 cleavage was lower in CC compared with control tissue. Additionally, the histone H3 clipping was performed by serine and aspartyl proteases in HeLa cells. These results suggest that histone H3 clipping operates as part of post-translational modification system in CC.

Skeletal manifestations of Marfan syndrome associated to heterozygous R2726W FBN1 variant: sibling case report and literature review.

BACKGROUND: FBN1 (15q21.1) encodes fibrillin-1, a large glycoprotein which is a major component of microfibrils that are widely distributed in structural elements of elastic and non-elastic tissues. FBN1 variants are responsible for the related connective tissue disorders, grouped under the generic term of type-1 fibrillinopathies, which include Marfan syndrome (MFS), MASS syndrome (Mitral valve prolapse, Aortic enlargement, Skin and Skeletal findings, Acromicric dysplasia, Familial ectopia lentis, Geleophysic dysplasia 2, Stiff skin syndrome, and dominant Weill-Marchesani syndrome. CASE PRESENTATION: Two siblings presented with isolated skeletal manifestations of MFS, including severe pectus excavatum, elongated face, scoliosis in one case, and absence of other clinical features according to Ghent criteria diagnosis, were screened for detection of variants in whole FBN1 gene (65 exons). Both individuals were heterozygous for the R2726W variant. This variant has been previously reported in association with some skeletal features of Marfan syndrome in the absence of both tall stature and non-skeletal features. These features are consistent with the presentation of the siblings reported here. CONCLUSION: The presented cases confirm that the R2726W FBN1 variant is associated with skeletal features of MFS in the absence of cardiac or ocular findings. These findings confirm that FBN1 variants are associated with a broad phenotypic spectrum and the value of sequencing in atypical cases.

Extracellular vesicles from women with breast cancer promote an epithelial-mesenchymal transition-like process in mammary epithelial cells MCF10A.

Extracellular vesicles (EVs) mediate many stages of tumor progression including angiogenesis, escape from immune surveillance, and extracellular matrix degradation. We studied whether EVs from plasma of women with breast cancer are able to induce an epithelial-mesenchymal transition (EMT) process in mammary epithelial cells MCF10A. Our findings demonstrate that EVs from plasma of breast cancer patients induce a downregulation of E-cadherin expression and an increase of vimentin and N-cadherin expression. Moreover, EVs induce migration and invasion, as well as an increase of NFκB-DNA binding activity and MMP-2 and MMP-9 secretions. In summary, our findings demonstrate, for the first time, that EVs from breast cancer patients induce an EMT-like process in human mammary non-tumorigenic epithelial cells MCF10A.

Increased serum levels of inflammatory mediators and low frequency of regulatory T cells in the peripheral blood of preeclamptic Mexican women.

Regulatory T cells (T(regs); CD4+CD25(high)Foxp3+) are critical in maintaining immune tolerance during pregnancy and uterine vascularization. In this study, we show that, in Mexican women with different preeclamptic severity levels, the number of T(regs) and the subset of CD4+CD25(high)Foxp3+ are decreased compared with those of normotensive pregnant women (NP). Moreover, a systemic inflammatory state is a pivotal feature in the pathogenesis of this disorder and could be related to hypertension and endothelial dysfunction. Likewise, we observed elevated levels of IL-6, TNF-α, and IL-8 in the serum of severe preeclamptic patients (SPE); no differences were found in the IL-1ß and IL-10 levels compared with those of NP patients. An analysis of chemokines in the preeclamptic serum samples showed high levels of CXCL10, CCL2, and CXCL9. Our findings suggest that the preeclamptic state is linked with systemic inflammation and reduced numbers of T(regs).

[Tumor necrosis factor alfa in cardiovascular diseases: molecular biology and genetics]. / El factor de necrosis tumoral alfa en las enfermedades cardiovasculares: biología molecular y genética.

Cardiovascular diseases are a major public health problem globally. In 1997, cardiovascular disease caused 41% of deaths in the United States. It has been reported that about 60 million people in the United States have some form of cardiovascular disease. These entities are chronic conditions initiated by a dysregulation of the immune response. One gene and its protein product -tumor necrosis factor a (TNF-α)- a powerful pleiotropic cytokine with multiple cellular functions, plays a role in the inflammation, initiation, development, susceptibility, severity, and response to treatment, etc. of coronary artery disease (CAD). The focus of the present review is to summarize recent evidence showing the biological role of TNF-α in the initiation and progression of endothelial dysfunction and complications of atherosclerosis, and as a genetic variation of TNF-α confer susceptibility, severity, and treatment response in CAD: ST-segment elevation myocardial infarction and non-ST segment elevation myocardial infarction, unstable angina, and coronary restenosis.

Elevated concentration of microvesicles isolated from peripheral blood in breast cancer patients.

BACKGROUND AND AIMS: Breast cancer is the most common cancer and the main cause of cancer deaths in women worldwide. Microvesicles (MVs) are fragments of the plasma membrane secreted from cytoplasmic membrane compartments by normal and malignant cells. An increase in MV number has been found in peripheral blood of patients with several diseases including cancer. We hypothesized that MV number and the relative amount of focal adhesion kinase (FAK) and epidermal growth factor receptor (EGFR) proteins in plasma fractions enriched in MVs and deprived of platelet-derived MVs are related to the presence of breast cancer. METHODS: Plasma fractions enriched in MVs and deprived of platelet-derived MVs were obtained by differential centrifugation of blood samples. MV number was evaluated by BD TruCOUNT Tubes (BD Biosciences). FAK and EGFR proteins were analyzed by Western blot. RESULTS: MV number in plasma fractions enriched with MVs and deprived of platelet-derived MVs is higher in breast cancer patients with stages I-IV as well as with T2-T4 tumors, in comparison to control group. In addition, plasma fractions enriched in MVs present FAK and EGFR proteins and their amount is increased in some stages of breast cancer in comparison to control group. CONCLUSIONS: Our findings strongly suggest that MV number and the amount of FAK and EGFR in plasma fractions enriched in MVs are associated with some stages of breast cancer.

[Profiles of cell proliferation and apoptosis in the mouse epithelial regeneration model K6b-E6/E7]. / Perfiles de proliferación celular y apoptosis en elmodelo murino de regeneración epitelial K6b-E6/E7.

BACKGROUND: Mammals have limited epithelial regeneration capacity. The K6b-E6/E7 mice model has been described as useful for the study of epithelial regeneration. The objective of this study is to compare the expression of E6/E7 oncogenes with those of cell proliferation and apoptosis during epithelization. The hypothesis of this study is that alterations in cell proliferation and apoptosis in K6b-E6/E7 mice will only occur during epithelization. METHODS: Deep 2 mm punches were performed in the middle of transgenic and control mice's ears. A biopsy was collected from the epithelization zone 72 hours and 2 weeks post-injury. Assays for cell proliferation and apoptosis were carried out by immunohistochemistry and TUNEL techniques, respectively. RT-PCR in situ was performed to compare E6/E7 expressions in the areas studied. RESULTS: Transgenic strain K6b-E6/E7 presented more proliferative cells and less apoptotic cells in epithelizated zones. This effect was limited to suprabasal stratum only, and correlates with E6/E7 oncogenes expression. Two weeks post-injury, cell proliferation and apoptosis were similar in both samples as the E6/E7 expression went down. CONCLUSION: K6b-E6/E7 mouse model is useful for epithelial regeneration. Its mechanisms should be considered for the treatment of deep wounds.

[Molecular analysis of the CAG repeat among patients with Type-2 spinocerebellar ataxia in the Mexican population]. / Análisis molecular de los repetidos CAG en pacientes mexicanos con ataxia espinocerebelosa tipo 2.

BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) results from the expansion of a CAG triplet located within the coding sequence of the ataxin-2 gene, which ultimately provokes the incorporation of a stretch of polyglutamines in the mutant protein. METHODS: We determined by PCR and capillary electrophoresis the number of ataxin2 gene CAG repeats in 66 individuals belonging to 3 families, clinically diagnosed with SCA2, and 400 subjects from a sample of the mestizo Mexican population. RESULTS: The CAG repeat expansion was found in 11 symptomatic subjects and four asymptomatic individuals, confirming the SCA2 clinical diagnosis in two out of the three families studied. We noted that patients with longer CAG repeat numbers have an early disease onset, a phenomenon known as anticipation. Wild-type alleles showed a CAG repeat range between 13 and 30, and the allele carrying 22 CAG repeats was the most common among our sample. Mutant alleles also displayed a range between 36 and 54 CAG repeats. CONCLUSIONS: The identification of the CAG repeat expansion facilitates an accurate SCA2 diagnosis.

Análisis molecular de los repetidos CAG en pacientes mexicanos con ataxia espinocerebelosa tipo 2 / Molecular analysis of the CAG repeat among patients with Type-2 spinocerebellar ataxia in the Mexican population

Antecedentes: La ataxia espinocerebelosa tipo 2 es causada por la expansión del repetido CAG presente en el exón 1 del gen de la ataxina-2, lo cual origina la incorporación de un segmento de poliglutaminas en la proteína mutante. Métodos: Mediante reacción en cadena de la polimerasa y electroforesis capilar se determinó el número de repetidos CAG del gen de la ataxina-2 en 66 individuos pertenecientes a tres familias mexicanas diagnosticadas clínicamente con ataxia espinocerebelosa tipo 2, y en 400 individuos de una muestra de población mestiza mexicana. Resultados: Se identificó la expansión del repetido CAG en 11 sujetos con sintomatología de ataxia espinocerebelosa tipo 2 y en cuatro individuos asintomáticos, lo que confirmó el diagnóstico en dos de las tres familias analizadas. Se determinó que los pacientes con mayor número de repetidos desarrollaron la sintomatología de la enfermedad a una edad más temprana, fenómeno conocido como “anticipación”. Los alelos silvestres presentaron un rango entre 13 y 30 repetidos CAG, siendo el alelo de 22 repetidos el más frecuente, mientras que los alelos mutados mostraron un rango de 36 a 54 repetidos. Conclusiones: La identificación de la expansión del repetido CAG del gen de la ataxina-2 confirmó el diagnóstico clínico de ataxia espinocerebelosa tipo 2.

BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) results from the expansion of a CAG triplet located within the coding sequence of the ataxin-2 gene, which ultimately provokes the incorporation of a stretch of polyglutamines in the mutant protein. METHODS: We determined by PCR and capillary electrophoresis the number of ataxin2 gene CAG repeats in 66 individuals belonging to 3 families, clinically diagnosed with SCA2, and 400 subjects from a sample of the mestizo Mexican population. RESULTS: The CAG repeat expansion was found in 11 symptomatic subjects and four asymptomatic individuals, confirming the SCA2 clinical diagnosis in two out of the three families studied. We noted that patients with longer CAG repeat numbers have an early disease onset, a phenomenon known as anticipation. Wild-type alleles showed a CAG repeat range between 13 and 30, and the allele carrying 22 CAG repeats was the most common among our sample. Mutant alleles also displayed a range between 36 and 54 CAG repeats. CONCLUSIONS: The identification of the CAG repeat expansion facilitates an accurate SCA2 diagnosis.