Publications by authors named "Andre M Ribeiro-Dos-Santos"

Article Synopsis
  • * Most genetic studies on drug responses have focused on European and North American populations, leaving a gap in understanding how these drugs affect Indigenous groups, particularly in the Amazon.
  • * This study found unique genetic variants in Amazonian Indigenous populations related to corticosteroid treatment, emphasizing the need for precision medicine tailored to their genetic makeup to improve treatment outcomes and reduce adverse effects.
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  • - The study investigates how genomic context affects gene regulation, focusing on the Igf2/H19 locus in mice, where CTCF binds to a control region that determines which gene is activated based on enhancers.
  • - By using synthetic regulatory genomics to replace the native genetic locus with 157-kb payloads, researchers discovered new long-range regulatory relationships and how enhancers interact with their environment.
  • - The research found that while the H19 enhancers depend on their native location, the Sox2 locus control region operates independently, suggesting that the context of enhancers is crucial for their function across different cell types.
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Methods for analyzing the full complement of a biomolecule type, e.g., proteomics or metabolomics, generate large amounts of complex data.

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Coronavirus disease 2019 (COVID-19) is an infection caused by SARS-CoV-2. Genome-wide association studies (GWASs) have suggested a strong association of genetic factors with the severity of the disease. However, many of these studies have been completed in European populations, and little is known about the genetic variability of indigenous peoples' underlying infection by SARS-CoV-2.

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Article Synopsis
  • * The research focused on the genomic profile of 64 Indigenous individuals, identifying high-impact genetic variants that suggest greater susceptibility to mercury exposure compared to global populations.
  • * As the first study of its kind, the findings aim to inform public policies by identifying at-risk populations through genomic analysis related to mercury metabolism.
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Genetically engineered mouse models (GEMMs) help us to understand human pathologies and develop new therapies, yet faithfully recapitulating human diseases in mice is challenging. Advances in genomics have highlighted the importance of non-coding regulatory genome sequences, which control spatiotemporal gene expression patterns and splicing in many human diseases. Including regulatory extensive genomic regions, which requires large-scale genome engineering, should enhance the quality of disease modelling.

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Enhancer function is frequently investigated piecemeal using truncated reporter assays or single deletion analysis. Thus it remains unclear to what extent enhancer function at native loci relies on surrounding genomic context. Using the Big-IN technology for targeted integration of large DNAs, we analyzed the regulatory architecture of the murine / locus, a paradigmatic model of enhancer selectivity.

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Gastric Cancer is a disease associated with environmental and genetic changes, becoming one of the most prevalent cancers around the world and with a high incidence in Brazil. However, despite being a highly studied neoplastic type, few efforts are aimed at populations with a unique background and genetic profile, such as the indigenous peoples of the Brazilian Amazon. Our study characterized the molecular profile of five genes associated with the risk of developing gastric cancer by sequencing the complete exome of 64 indigenous individuals belonging to 12 different indigenous populations in the Amazon.

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Sox2 expression in mouse embryonic stem cells (mESCs) depends on a distal cluster of DNase I hypersensitive sites (DHSs), but their individual contributions and degree of interdependence remain a mystery. We analyzed the endogenous Sox2 locus using Big-IN to scarlessly integrate large DNA payloads incorporating deletions, rearrangements, and inversions affecting single or multiple DHSs, as well as surgical alterations to transcription factor (TF) recognition sequences. Multiple mESC clones were derived for each payload, sequence-verified, and analyzed for Sox2 expression.

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Hereditary gastric cancers (HGCs) are supposed to be rare and difficult to identify. Nonetheless, many cases of young patients with gastric cancer (GC) fulfill the clinical criteria for considering this diagnosis but do not present the defined pathogenic mutations necessary to meet a formal diagnosis of HGC. Moreover, GC in young people is a challenging medical situation due to the usual aggressiveness of such cases and the potential risk for their relatives when related to a germline variant.

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Circular RNAs (circRNAs) are a class of long non-coding RNAs that have the ability to sponge RNA-Binding Proteins (RBPs). Triple-negative breast cancer (TNBC) has very aggressive behavior and poor prognosis for the patient. Here, we aimed to characterize the global expression profile of circRNAs in TNBC, in order to identify potential risk biomarkers.

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Given the role of pharmacogenomics in the large variability observed in drug efficacy/safety, an assessment about the pharmacogenomic profile of patients prior to drug prescription or dose adjustment is paramount to improve adherence to treatment and prevent adverse drug reaction events. A population commonly underrepresented in pharmacogenomic studies is the Native American populations, which have a unique genetic profile due to a long process of geographic isolation and other genetic and evolutionary processes. Here, we describe the pharmacogenetic variability of Native American populations regarding 160 pharmacogenes involved in absorption, distribution, metabolism, and excretion processes and biological pathways of different therapies.

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A number of genomic variants related to native American ancestry may be associated with an increased risk of developing Acute Lymphoblastic Leukemia (ALL), which means that Latin American and hispanic populations from the New World may be relatively susceptible to this disease. However, there has not yet been any comprehensive investigation of the variants associated with susceptibility to ALL in traditional Amerindian populations from Brazilian Amazonia. We investigated the exomes of the 18 principal genes associated with susceptibility to ALL in samples of 64 Amerindians from this region, including cancer-free individuals and patients with ALL.

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Genetic factors associated with COVID-19 disease outcomes are poorly understood. This study aimed to associate genetic variants in the , , , , , , and genes with the risk of severe forms of COVID-19 in Amazonian Native Americans, and to compare the frequencies with continental populations. The study population was composed of 64 Amerindians from the Amazon region of northern Brazil.

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The specificity of interactions between genomic regulatory elements and potential target genes is influenced by the binding of insulator proteins such as CTCF, which can act as potent enhancer blockers when interposed between an enhancer and a promoter in a reporter assay. But not all CTCF sites genome-wide function as insulator elements, depending on cellular and genomic context. To dissect the influence of genomic context on enhancer blocker activity, we integrated reporter constructs with promoter-only, promoter and enhancer, and enhancer blocker configurations at hundreds of thousands of genomic sites using the transposase.

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The role of regulatory elements such as small ncRNAs and their mechanisms are poorly understood in infectious diseases. Tuberculosis is one of the oldest infectious diseases of humans and it is still a challenge to prevent and treat. Control of the infection, as well as its diagnosis, are still complex and current treatments used are linked to several side effects.

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Background: Next generation sequencing (NGS) has been a handy tool in clinical practice, mainly due to its efficiency and cost-effectiveness. It has been widely used in genetic diagnosis of several inherited diseases, and, in clinical oncology, it may enhance the discovery of new susceptibility genes and enable individualized care of cancer patients. In this context, we explored a pan-cancer panel in the investigation of germline variants in Brazilian patients presenting clinical criteria for hereditary cancer syndromes or familial history.

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Many sequence variants have been linked to complex human traits and diseases, but deciphering their biological functions remains challenging, as most of them reside in noncoding DNA. Here we have systematically assessed the binding of 270 human transcription factors to 95,886 noncoding variants in the human genome using an ultra-high-throughput multiplex protein-DNA binding assay, termed single-nucleotide polymorphism evaluation by systematic evolution of ligands by exponential enrichment (SNP-SELEX). The resulting 828 million measurements of transcription factor-DNA interactions enable estimation of the relative affinity of these transcription factors to each variant in vitro and evaluation of the current methods to predict the effects of noncoding variants on transcription factor binding.

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Article Synopsis
  • Studies on the peopling of South America have been limited by a lack of genetic data, particularly from Indigenous groups in the eastern Amazon.
  • Researchers analyzed the genetic variation of 58 Native American individuals from eight Amazonian populations to understand demographic patterns.
  • Findings reveal a clear genetic difference between Andean and Amazonian populations, supporting a migration theory involving movement along both the Pacific and Atlantic coasts, with southeastern South America populated by migrations from the north.
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Background: Melanoma is the most aggressive type of skin cancer and is associated with environmental and genetic risk factors. It originates in melanocytes, the pigment-producing cells. Single nucleotide polymorphisms (SNPs) in pigmentation genes have been described in melanoma risk modulation, but knowledge in the field is still limited.

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Effective public response to a pandemic relies upon accurate measurement of the extent and dynamics of an outbreak. Viral genome sequencing has emerged as a powerful approach to link seemingly unrelated cases, and large-scale sequencing surveillance can inform on critical epidemiological parameters. Here, we report the analysis of 864 SARS-CoV-2 sequences from cases in the New York City metropolitan area during the COVID-19 outbreak in spring 2020.

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Article Synopsis
  • - Gastric cancer (GC) is a significant global health issue, and research into its molecular mechanisms aims to discover new biomarkers for early diagnosis.
  • - The study utilized small-RNA sequencing to examine the expression of PIWI-interacting RNAs (piRNAs) in gastric cancer patients, identifying 698 piRNAs with 14 being differentially expressed between cancerous and non-cancerous tissues.
  • - Three specific piRNAs (piR-48966*, piR-49145, piR-31335*) were found to be potential risk biomarkers for gastric cancer, highlighting the need to reconsider adjacent tissues in research as they undergo molecular changes related to the disease.
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  • Leprosy, caused by Mycobacterium leprae, affects over 200,000 people annually, leading to nerve damage and disabilities, with symptoms appearing 3-7 years after infection.
  • Recent research discovered that most piRNAs, small noncoding RNAs involved in gene regulation, are downregulated in skin lesions of leprosy patients, which could link to various disease processes like apoptosis and neuropathic pain.
  • Understanding the role of piRNAs in leprosy may uncover new therapeutic targets to address nerve damage, as current treatments are lacking for this significant aspect of the disease.
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Effective public response to a pandemic relies upon accurate measurement of the extent and dynamics of an outbreak. Viral genome sequencing has emerged as a powerful approach to link seemingly unrelated cases, and large-scale sequencing surveillance can inform on critical epidemiological parameters. Here, we report the analysis of 864 SARS-CoV-2 sequences from cases in the New York City metropolitan area during the COVID-19 outbreak in Spring 2020.

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Introduction: The nudix hydrolase 15 (NUDT15) gene acts in the metabolism of thiopurine, by catabolizing its active metabolite thioguanosine triphosphate into its inactivated form, thioguanosine monophosphate. The frequency of alternative NUDT15 alleles, in particular those that cause a drastic loss of gene function, varies widely among geographically distinct populations. In the general population of northern Brazilian, high toxicity rates (65%) have been recorded in patients treated with the standard protocol for acute lymphoblastic leukemia, which involves thiopurine-based drugs.

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