1 3019 123 GENETICS AND EPIGENETICS OF NASAL POLYPOSIS: A SYSTEMATIC REVIEW. CHRONIC RHINOSINUSITIS (CRS) IS AN INFLAMMATORY DISEASE OF THE NOSE AND PARANASAL SINUSES THAT IS OFTEN ASSOCIATED WITH NASAL POLYPOSIS (CRSWNP) IN THE MOST SEVERE CASES. AS IN OTHER COMPLEX DISEASES, GENETIC FACTORS ARE THOUGHT TO PLAY AN IMPORTANT ROLE IN THE RISK AND DEVELOPMENT OF THE DISEASE. ENVIRONMENT MAY ALSO MODULATE THE EPIGENETIC SIGNATURE IN AFFECTED PATIENTS. IN THE PRESENT SYSTEMATIC REVIEW, WE AIMED TO COMPILE ALL PUBLISHED DATA ON GENETIC AND EPIGENETIC VARIATIONS IN CRSWNP SINCE 2000. WE FOUND 104 ARTICLES, 24 OF WHICH WERE RELATED TO EPIGENETIC STUDIES. WE IDENTIFIED MORE THAN 150 GENETIC VARIANTS IN 99 GENES INVOLVED IN THE PATHOGENESIS OF NASAL POLYPOSIS. THESE WERE CLUSTERED INTO 8 MAIN NETWORKS, LINKING GENES INVOLVED IN INFLAMMATION AND IMMUNE RESPONSE (EG, MHC), CYTOKINE GENES (EG, TNF), LEUKOTRIENE METABOLISM, AND THE EXTRACELLULAR MATRIX. A TOTAL OF 89 MIRNAS WERE ALSO IDENTIFIED; THESE ARE ASSOCIATED MAINLY WITH BIOLOGICAL FUNCTIONS SUCH AS THE CELL CYCLE, INFLAMMATION, AND THE IMMUNE RESPONSE. WE PROPOSE A POTENTIAL RELATIONSHIP BETWEEN GENES AND THE MIRNAS IDENTIFIED THAT MAY OPEN NEW LINES OF INVESTIGATION. AN IN-DEPTH KNOWLEDGE OF GENE VARIANTS AND EPIGENETIC TRAITS COULD HELP US TO DESIGN MORE TAILORED TREATMENT FOR PATIENTS WITH CRSWNP. 2021 2 3746 47 INSIGHTS INTO THE EPIGENETICS OF CHRONIC RHINOSINUSITIS WITH AND WITHOUT NASAL POLYPS: A SYSTEMATIC REVIEW. BACKGROUND: EPIGENETICS FACILITATES INSIGHTS ON THE IMPACT OF HOST ENVIRONMENT ON THE GENESIS OF CHRONIC RHINOSINUSITIS (CRS) THROUGH MODULATIONS OF HOST GENE EXPRESSION AND ACTIVITY. EPIGENETIC MECHANISMS SUCH AS DNA METHYLATION CAUSE REVERSIBLE BUT HERITABLE CHANGES IN GENE EXPRESSION OVER GENERATIONS OF PROGENY, WITHOUT ALTERING THE DNA BASE-PAIR SEQUENCES. THESE STUDIES OFFER A CRITICAL UNDERSTANDING OF THE ENVIRONMENT-INDUCED CHANGES THAT RESULT IN HOST PREDISPOSITION TO DISEASE AND MAY HELP IN DEVELOPING NOVEL BIOMARKERS AND THERAPEUTICS. THE GOAL OF THIS SYSTEMATIC REVIEW IS TO SUMMARIZE THE CURRENT EVIDENCE ON EPIGENETICS OF CRS WITH A FOCUS ON CHRONIC RHINOSINUSITIS WITH NASAL POLYPS (CRSWNP) AND HIGHLIGHT GAPS THAT MERIT FURTHER RESEARCH. METHODS: A SYSTEMATIC REVIEW OF THE ENGLISH LANGUAGE LITERATURE WAS PERFORMED TO IDENTIFY INVESTIGATIONS RELATED TO EPIGENETIC STUDIES IN SUBJECTS WITH CRS. RESULTS: THE REVIEW IDENTIFIED 65 STUDIES. THESE HAVE FOCUSED ON DNA METHYLATION AND NON-CODING RNAS, WITH ONLY A FEW ON HISTONE DEACETYLATION, ALTERNATIVE POLYADENYLATION, AND CHROMATIN ACCESSIBILITY. STUDIES INCLUDE THOSE INVESTIGATING IN VIVO AND IN VITRO CHANGES OR BOTH. STUDIES ALSO INCLUDE ANIMAL MODELS OF CRS. ALMOST ALL HAVE BEEN CONDUCTED IN ASIA. THE GENOME-WIDE STUDIES OF DNA METHYLATION FOUND DIFFERENCES IN GLOBAL METHYLATION BETWEEN CRSWNP AND CONTROLS, WHILE OTHERS SPECIFICALLY FOUND SIGNIFICANT DIFFERENCES IN METHYLATION OF THE CPG SITES OF THE THYMIC STROMAL LYMPHOPOIETIN (TSLP), IL-8, AND PLAT. IN ADDITION, DNA METHYLTRANSFERASE INHIBITORS AND HISTONE DEACETYLASE INHIBITORS WERE STUDIED AS POTENTIAL THERAPEUTIC AGENTS. MAJORITY OF THE STUDIES INVESTIGATING NON-CODING RNAS FOCUSED ON MICRO-RNAS (MIRNA) AND FOUND DIFFERENCES IN GLOBAL EXPRESSION OF MIRNA LEVELS. THESE STUDIES ALSO REVEALED SOME PREVIOUSLY KNOWN AS WELL AS NOVEL TARGETS AND PATHWAYS SUCH AS TUMOR NECROSIS FACTOR ALPHA, TGF BETA-1, IL-10, EGR2, ARYL HYDROCARBON RECEPTOR, PI3K/AKT PATHWAY, MUCIN SECRETION, AND VASCULAR PERMEABILITY. OVERALL, THE STUDIES HAVE FOUND A DYSREGULATION IN PATHWAYS/GENES INVOLVING INFLAMMATION, IMMUNE REGULATION, TISSUE REMODELING, STRUCTURAL PROTEINS, MUCIN SECRETION, ARACHIDONIC ACID METABOLISM, AND TRANSCRIPTION. CONCLUSIONS: EPIGENETIC STUDIES IN CRS SUBJECTS SUGGEST THAT THERE IS LIKELY A MAJOR IMPACT OF THE ENVIRONMENT. HOWEVER, THESE ARE ASSOCIATION STUDIES AND DO NOT DIRECTLY IMPLY PATHOGENESIS. LONGITUDINAL STUDIES IN GEOGRAPHICALLY AND RACIALLY DIVERSE POPULATION COHORTS ARE NECESSARY TO QUANTIFY GENETIC VS. ENVIRONMENTAL RISKS FOR CRSWNP AND CRS WITHOUT NASAL POLYPS AND ASSESS HERITABILITY RISK, AS WELL AS DEVELOP NOVEL BIOMARKERS AND THERAPEUTIC AGENTS. 2023 3 3014 40 GENETICS AND EPIGENETICS OF CHRONIC RHINOSINUSITIS. DISCERNING THE GENETICS AND EPIGENETICS OF CHRONIC RHINOSINUSITIS (CRS) MAY OPTIMIZE OUTCOMES THROUGH EARLY DIAGNOSTICS, PERSONALIZED AND NOVEL THERAPEUTICS, AND EARLY PROGNOSTICATION. CRS ASSOCIATED WITH CYSTIC FIBROSIS AND PRIMARY CILIARY DYSKINESIA HAS WELL-CHARACTERIZED GENETIC MUTATIONS. MOST CRS SUBJECTS, HOWEVER, DO NOT EXHIBIT IDENTIFIABLE MONOGENIC ALTERATIONS. CLUSTERING IN RELATED INDIVIDUALS IS SEEN IN CRS WITH NASAL POLYPS. SPOUSES OF SUBJECTS WITH CRS WITHOUT NASAL POLYPS ALSO MAY BE AT INCREASED RISK OF THE SAME DISEASE. THESE OBSERVATIONS GENERATE QUESTIONS ON GENETIC AND ENVIRONMENTAL INFLUENCES IN CRS. GENOME-WIDE ASSOCIATION STUDIES HAVE IDENTIFIED VARIATIONS AND POLYMORPHISMS BETWEEN CRS AND CONTROL SUBJECTS IN GENES RELATED TO INNATE AND ADAPTIVE IMMUNITY. CANDIDATE GENE AND TRANSCRIPTOMICS STUDIES HAVE INVESTIGATED AND IDENTIFIED GENETIC VARIATIONS RELATED TO IMMUNITY, INFLAMMATION, EPITHELIAL BARRIER FUNCTION, STRESS-RESPONSE, ANTIGEN PROCESSING, T-CELL REGULATION, AND CYTOKINES IN CRS. EPIGENETIC STUDIES HAVE IDENTIFIED MECHANISMS THROUGH WHICH ENVIRONMENTAL FACTORS MAY AFFECT THESE GENE FUNCTIONS. HOWEVER, CAUSALITY IS NOT DETERMINED FOR MOST VARIATIONS. INFERENCES DRAWN FROM THESE DATA MUST BE MEASURED BECAUSE MOST INVESTIGATIONS REPORT UNREPLICATED RESULTS FROM SMALL STUDY POPULATIONS. LARGE, REPLICATED STUDIES IN TIGHT COHORTS ACROSS DIVERSE POPULATIONS REMAIN A PRESSING NEED IN STUDYING CRS GENETICS. 2023 4 2217 24 EPIGENETIC MODIFICATIONS IN CHRONIC RHINOSINUSITIS WITH AND WITHOUT NASAL POLYPS. CHRONIC RHINOSINUSITIS (CRS) HAS BROUGHT A HUGE SOCIOECONOMIC BURDEN. HOWEVER, ITS MECHANISM IS STILL ELUSIVE, WHICH MAY INVOLVE GENETIC, ENVIRONMENTAL AND SOME OTHER FACTORS. EPIGENETIC ANALYSES HAVE BEEN CONDUCTED TO EXPLORE THE MECHANISMS UNDERLYING CRS. HERE, WE REVIEWED THE FRUITS IN THE EPIGENETIC STUDIES ON DNA METHYLATION, HISTONE MODIFICATION, AND NON-CODING RNA REGULATION. WE CONCLUDED THAT THE EPIGENETIC RESEARCH ON CRS HAS MADE GREAT BREAKTHROUGHS, ESPECIALLY IN THE PAST 5 YEARS AND THE FIELD OF MICRORNAS. "EPIGENETIC THERAPIES" ARE EXPECTED TO BE DESIGNED TO TREAT CRS IN THE FUTURE. 2022 5 822 33 CHARACTERIZATION OF BLOOD SURROGATE IMMUNE-METHYLATION BIOMARKERS FOR IMMUNE CELL INFILTRATION IN CHRONIC INFLAMMAGING DISORDERS. ALZHEIMER'S DISEASE (AD) AND ATHEROSCLEROSIS ARE BOTH CHRONIC AGE- AND INFLAMMATION-DEPENDENT DISEASES. IN ADDITION, ATHEROSCLEROSIS IS FREQUENTLY OBSERVED IN AD PATIENTS INDICATING COMMON INVOLVEMENT OF VASCULAR COMPONENTS IN BOTH DISEASE ETIOLOGIES. RECENTLY, EPIGENOME-WIDE ASSOCIATION STUDIES HAVE IDENTIFIED EPIGENETIC ALTERATIONS, AND IN PARTICULARLY DNA METHYLATION CHANGES FOR BOTH DISORDERS. WE HYPOTHESIZED THE EXISTENCE OF A COMMON DNA METHYLATION PROFILE IN ATHEROSCLEROSIS AND AD WHICH MAY BE VALUABLE AS A BLOOD-BASED DNA METHYLATION INFLAMMAGING BIOMARKER. USING PUBLICLY AVAILABLE 450K ILLUMINA METHYLATION DATASETS, WE IDENTIFIED A CO-METHYLATION NETWORK ASSOCIATED WITH BOTH ATHEROSCLEROSIS AND AD IN WHOLE BLOOD SAMPLES. THIS METHYLATION PROFILE APPEARED TO INDICATE SHIFTS IN BLOOD IMMUNE CELL TYPE DISTRIBUTION. REMARKABLY, SIMILAR METHYLATION CHANGES WERE ALSO DETECTED IN DISEASE TISSUES, INCLUDING AD BRAIN TISSUES, ATHEROSCLEROTIC PLAQUES, AND TUMORS AND WERE FOUND TO CORRELATE WITH IMMUNE CELL INFILTRATION. IN ADDITION, THIS IMMUNE-RELATED METHYLATION PROFILE COULD ALSO BE DETECTED IN OTHER INFLAMMAGING DISEASES, INCLUDING PARKINSON'S DISEASE AND OBESITY, BUT NOT IN MULTIPLE SCLEROSIS, SCHIZOPHRENIA, AND OSTEOPOROSIS. IN CONCLUSION, WE IDENTIFIED A BLOOD-BASED IMMUNE-RELATED DNA METHYLATION SIGNATURE IN MULTIPLE INFLAMMAGING DISEASES ASSOCIATED WITH CHANGES IN BLOOD IMMUNE CELL COUNTS AND PREDICTIVE FOR IMMUNE CELL INFILTRATION IN DISEASED TISSUES. IN ADDITION TO EPIGENETIC CLOCK MEASUREMENTS, THIS IMMUNE-METHYLATION SIGNATURE MAY BECOME A VALUABLE BLOOD-BASED BIOMARKER TO PREVENT CHRONIC INFLAMMATORY DISEASE DEVELOPMENT OR MONITOR LIFESTYLE INTERVENTION STRATEGIES WHICH PROMOTE HEALTHY AGING. 2019 6 5031 34 PERSPECTIVES ON THE ETIOLOGY OF CHRONIC RHINOSINUSITIS: AN IMMUNE BARRIER HYPOTHESIS. BACKGROUND: CHRONIC RHINOSINUSITIS (CRS) HAS BEEN DEFINED AS PERSISTENT SYMPTOMATIC INFLAMMATION OF THE NASAL AND SINUS MUCOSA RESULTING FROM THE INTERACTION OF MULTIPLE HOST AND ENVIRONMENTAL FACTORS. RECENT STUDIES HAVE IMPLICATED ALTERNARIA FUNGI OR TOXIGENIC STAPHYLOCOCCUS AUREUS AS CRITICAL AGENTS IN CRS PATHOGENESIS. THE EMPHASIS ON ENVIRONMENTAL AGENTS IN CRS ETIOLOGY HAS FOCUSED INTEREST TOWARD ELIMINATION OF THOSE AGENTS AS THE PRIME MECHANISM OF THERAPY. THIS VIEWPOINT IS IN MARKED CONTRAST TO THE CURRENT PERSPECTIVE ON SOME OTHER CHRONIC INFLAMMATORY EPITHELIAL DISORDERS THAT AFFLICT THE SKIN, LUNGS, AND GUT, WHEREIN HOST FACTORS ARE BELIEVED TO PREDISPOSE TO DISEASE EXPRESSION IN THE PRESENCE OF UBIQUITOUS ENVIRONMENTAL AGENTS. METHODS: THE CURRENT REVIEW EVALUATES CRS ETIOLOGY FROM THIS PERSPECTIVE AND CONSIDERS THAT CRS DEVELOPS, IN PART, AS AN OUTCOME OF A DYSFUNCTIONAL HOST RESPONSE. SPECIFICALLY, EVIDENCE FROM OUR LABORATORY AND OTHERS WILL BE REVIEWED INDICATING THAT CRS IS ASSOCIATED WITH A FAILURE OF THE MECHANICAL AND IMMUNOLOGIC BARRIERS ACROSS THE NASAL MUCOSA. THE HYPOTHESIS WOULD FURTHER PROPOSE THAT GENETIC AND EPIGENETIC VARIATION PREDISPOSES SUSCEPTIBLE INDIVIDUALS TO BARRIER FAILURE IN THE PRESENCE OF ENVIRONMENTAL STRESS LEADING TO CRS. RESULTS: FROM THIS UNIFYING PERSPECTIVE, BACTERIA AND FUNGI ARE SEEN AS DISEASE MODIFIERS RATHER THAN PRIMARY ETIOLOGIC AGENTS. CONCLUSION: THE GOAL IS TO PLACE CONCEPTS OF CRS PATHOPHYSIOLOGY IN A FRAMEWORK CONSISTENT WITH A CURRENT UNDERSTANDING OF CHRONIC INFLAMMATION IN GENERAL AND EPITHELIAL DISEASE IN PARTICULAR. 2008 7 2558 36 EPIGENETICS IN SUSCEPTIBILITY, PROGRESSION, AND DIAGNOSIS OF PERIODONTITIS. PERIODONTITIS IS CHARACTERIZED BY IRREVERSIBLE DESTRUCTION OF PERIODONTAL TISSUE. AT PRESENT, THE ACCEPTED ETIOLOGY OF PERIODONTITIS IS BASED ON A THREE-FACTOR THEORY INCLUDING PATHOGENIC BACTERIA, HOST FACTORS, AND ACQUIRED FACTORS. PERIODONTITIS DEVELOPMENT USUALLY TAKES A DECADE OR LONGER AND IS THEREFORE CALLED CHRONIC PERIODONTITIS (CP). TO SEARCH FOR GENETIC FACTORS ASSOCIATED WITH CP, SEVERAL GENOME-WIDE ASSOCIATION STUDY (GWAS) ANALYSES WERE CONDUCTED; HOWEVER, POLYMORPHISMS ASSOCIATED WITH CP HAVE NOT BEEN IDENTIFIED. EPIGENETICS, ON THE OTHER HAND, INVOLVES ACQUIRED TRANSCRIPTIONAL REGULATORY MECHANISMS DUE TO REVERSIBLY ALTERED CHROMATIN ACCESSIBILITY. EPIGENETIC STATUS IS A CONDITION SPECIFIC TO EACH TISSUE AND CELL, MOSTLY DETERMINED BY THE RESPONSES OF HOST CELLS TO STIMULATIONS BY LOCAL FACTORS, LIKE BACTERIAL INFLAMMATION, AND SYSTEMIC FACTORS SUCH AS NUTRITION STATUS, METABOLIC DISEASES, AND HEALTH CONDITIONS. SIGNIFICANTLY, EPIGENETIC STATUS HAS BEEN LINKED WITH THE ONSET AND PROGRESSION OF SEVERAL ACQUIRED DISEASES. THUS, EPIGENETIC FACTORS IN PERIODONTAL TISSUES ARE ATTRACTIVE TARGETS FOR PERIODONTITIS DIAGNOSIS AND TREATMENTS. IN THIS REVIEW, WE INTRODUCE ACCUMULATING EVIDENCE TO REVEAL THE EPIGENETIC BACKGROUND EFFECTS RELATED TO PERIODONTITIS CAUSED BY GENETIC FACTORS, SYSTEMIC DISEASES, AND LOCAL ENVIRONMENTAL FACTORS, SUCH AS SMOKING, AND CLARIFY THE UNDERLYING MECHANISMS BY WHICH EPIGENETIC ALTERATION INFLUENCES THE SUSCEPTIBILITY OF PERIODONTITIS. 2022 8 3026 39 GENETICS OF BEHCET'S DISEASE: FUNCTIONAL GENETIC ANALYSIS AND ESTIMATING DISEASE HERITABILITY. BEHCET'S DISEASE IS A CHRONIC MULTISYSTEMIC INFLAMMATORY DISORDER CHARACTERIZED BY RECURRENT ORAL AND GENITAL ULCERS. ALTHOUGH ITS ETIOLOGY REMAINS UNCLEAR, IT IS THOUGHT THAT BOTH GENETIC AND ENVIRONMENTAL FACTORS CONTRIBUTE TO THE ONSET AND PROGRESSION OF BEHCET'S DISEASE. HERE, WE PROVIDE AN UPDATED VIEW OF THE GENETIC LANDSCAPE AND ARCHITECTURE OF BEHCET'S DISEASE. LARGE-SCALE GENETIC STUDIES PERFORMED TO DATE REVEALED 21 GENETIC SUSCEPTIBILITY LOCI ASSOCIATED WITH THE DISEASE AT A GWAS LEVEL OF SIGNIFICANCE (P-VALUE = 5 X 10(-8)). WE PERFORMED EPIGENETIC PATTERN ENRICHMENT ANALYSIS IN BEHCET'S DISEASE ASSOCIATED LOCI, PROVIDING NEW INSIGHTS INTO THE MOLECULAR MECHANISMS UNDERLYING ITS PATHOPHYSIOLOGY. OUR DATA SUGGEST THE CRUCIAL INVOLVEMENT OF SEVERAL IMMUNE CELL TYPES, INCLUDING NATURAL KILLER CELLS, MONOCYTES, AND B CELLS IN THE PATHOGENESIS OF THE DISEASE. PATHWAY ENRICHMENT ANALYSIS IDENTIFIED IMPORTANT BIOLOGICAL PROCESSES INVOLVED. USING LARGE-SCALE GENETIC DATA AVAILABLE FROM ~200 IMMUNE-RELATED LOCI (IMMUNOCHIP), WE ESTIMATE BEHCET'S DISEASE HERITABILITY TO BE AT LEAST 16%. WE FURTHER USED THE SAME APPROACH TO ESTIMATE THE HERITABILITY EXPLAINED BY THE KNOWN BEHCET'S DISEASE-ASSOCIATED LOCI, SUGGESTING THAT THEY EXPLAIN ~ 60% OF THE GENETIC COMPONENT UNDERLYING BEHCET'S DISEASE. THESE RESULTS INDICATE A SIGNIFICANT ROLE OF NON-GENETIC FACTORS IN CAUSING BEHCET'S DISEASE AND THAT ADDITIONAL GENETIC VARIATION INFLUENCING THE RISK OF BEHCET'S DISEASE REMAINS TO BE IDENTIFIED. FINALLY, WE CALCULATED A CUMULATIVE GENETIC RISK SCORE ACROSS POPULATIONS REINFORCING THE LINK BETWEEN GEOGRAPHIC VARIATIONS IN DISEASE PREVALENCE WITH ITS GENETIC COMPONENT. 2021 9 2920 36 GENE-SET ANALYSIS IS SEVERELY BIASED WHEN APPLIED TO GENOME-WIDE METHYLATION DATA. MOTIVATION: DNA METHYLATION IS AN EPIGENETIC MARK THAT CAN STABLY REPRESS GENE EXPRESSION. BECAUSE OF ITS BIOLOGICAL AND CLINICAL SIGNIFICANCE, SEVERAL METHODS HAVE BEEN DEVELOPED TO COMPARE GENOME-WIDE PATTERNS OF METHYLATION BETWEEN GROUPS OF SAMPLES. THE APPLICATION OF GENE SET ANALYSIS TO IDENTIFY RELEVANT GROUPS OF GENES THAT ARE ENRICHED FOR DIFFERENTIALLY METHYLATED GENES IS OFTEN A MAJOR COMPONENT OF THE ANALYSIS OF THESE DATA. THIS CAN BE USED, FOR EXAMPLE, TO IDENTIFY PROCESSES OR PATHWAYS THAT ARE PERTURBED IN DISEASE DEVELOPMENT. WE SHOW THAT GENE-SET ANALYSIS, AS IT IS TYPICALLY APPLIED TO GENOME-WIDE METHYLATION ASSAYS, IS SEVERELY BIASED AS A RESULT OF DIFFERENCES IN THE NUMBERS OF CPG SITES ASSOCIATED WITH DIFFERENT CLASSES OF GENES AND GENE PROMOTERS. RESULTS: WE DEMONSTRATE THIS BIAS USING PUBLISHED DATA FROM A STUDY OF DIFFERENTIAL CPG ISLAND METHYLATION IN LUNG CANCER AND A DATASET WE GENERATED TO STUDY METHYLATION CHANGES IN PATIENTS WITH LONG-STANDING ULCERATIVE COLITIS. WE SHOW THAT SEVERAL OF THE GENE SETS THAT SEEM ENRICHED WOULD ALSO BE IDENTIFIED WITH RANDOMIZED DATA. WE SUGGEST TWO EXISTING APPROACHES THAT CAN BE ADAPTED TO CORRECT THE BIAS. ACCOUNTING FOR THE BIAS IN THE LUNG CANCER AND ULCERATIVE COLITIS DATASETS PROVIDES NOVEL BIOLOGICAL INSIGHTS INTO THE ROLE OF METHYLATION IN CANCER DEVELOPMENT AND CHRONIC INFLAMMATION, RESPECTIVELY. OUR RESULTS HAVE SIGNIFICANT IMPLICATIONS FOR MANY PREVIOUS GENOME-WIDE METHYLATION STUDIES THAT HAVE DRAWN CONCLUSIONS ON THE BASIS OF SUCH STRONGLY BIASED ANALYSIS. CONTACT: CATHAL.SEOIGHE@NUIGALWAY.IE SUPPLEMENTARY INFORMATION: SUPPLEMENTARY DATA ARE AVAILABLE AT BIOINFORMATICS ONLINE. 2013 10 1546 30 DNA METHYLATION IN NASAL EPITHELIUM: STRENGTHS AND LIMITATIONS OF AN EMERGENT BIOMARKER FOR CHILDHOOD ASTHMA. ASTHMA IS ONE OF THE MOST WIDESPREAD CHRONIC RESPIRATORY CONDITIONS. THIS DISEASE PRIMARILY DEVELOPS IN CHILDHOOD AND IS INFLUENCED BY DIFFERENT FACTORS, MAINLY GENETICS AND ENVIRONMENTAL FACTORS. DNA METHYLATION IS AN EPIGENETIC MECHANISM WHICH MAY REPRESENT A BRIDGE BETWEEN THESE TWO FACTORS, PROVIDING A TOOL TO COMPREHEND THE INTERACTION BETWEEN GENETICS AND ENVIRONMENT. MOST EPIDEMIOLOGICAL STUDIES IN THIS FIELD HAVE BEEN CONDUCTED USING BLOOD SAMPLES, ALTHOUGH DNA METHYLATION MARKS IN BLOOD MAY NOT BE RELIABLE FOR DRAWING EXHAUSTIVE CONCLUSIONS ABOUT DNA METHYLATION IN THE AIRWAYS. BECAUSE OF THE ROLE OF NASAL EPITHELIUM IN ASTHMA AND THE TISSUE SPECIFICITY OF DNA METHYLATION, STUDYING THE RELATIONSHIP BETWEEN DNA METHYLATION AND CHILDHOOD ASTHMA MIGHT REVEAL CRUCIAL INFORMATION ABOUT THIS WIDESPREAD RESPIRATORY DISEASE. THE PURPOSE OF THIS REVIEW IS TO DESCRIBE CURRENT FINDINGS IN THIS FIELD OF RESEARCH. WE WILL PRESENT A VIEWPOINT OF SELECTED STUDIES, CONSIDER STRENGTHS AND LIMITATIONS, AND PROPOSE FUTURE RESEARCH IN THIS AREA. 2020 11 1518 32 DNA METHYLATION AS AN EPIGENETIC MECHANISM IN THE DEVELOPMENT OF MULTIPLE SCLEROSIS. THE EPIGENETIC MECHANISMS OF GENE EXPRESSION REGULATION ARE A GROUP OF THE KEY CELLULAR AND MOLECULAR PATHWAYS THAT LEAD TO INHERITED ALTERATIONS IN GENES' ACTIVITY WITHOUT CHANGING THEIR CODING SEQUENCE. DNA METHYLATION AT THE C5 POSITION OF CYTOSINE IN CPG DINUCLEOTIDES IS AMONGST THE CENTRAL EPIGENETIC MECHANISMS. CURRENTLY, THE NUMBER OF STUDIES THAT ARE DEVOTED TO THE IDENTIFICATION OF METHYLATION PATTERNS SPECIFIC TO MULTIPLE SCLEROSIS (MS), A SEVERE CHRONIC AUTOIMMUNE DISEASE OF THE CENTRAL NERVOUS SYSTEM, IS ON A RAPID RISE. HOWEVER, THE ISSUE OF THE CONTRIBUTION OF DNA METHYLATION TO THE DEVELOPMENT OF THE DIFFERENT CLINICAL PHENOTYPES OF THIS HIGHLY HETEROGENEOUS DISEASE HAS ONLY BEGUN TO ATTRACT THE ATTENTION OF RESEARCHERS. THIS REVIEW SUMMARIZES THE DATA ON THE MOLECULAR MECHANISMS UNDERLYING DNA METHYLATION AND THE MS RISK FACTORS THAT CAN AFFECT THE DNA METHYLATION PROFILE AND, THEREBY, MODULATE THE EXPRESSION OF THE GENES INVOLVED IN THE DISEASE'S PATHOGENESIS. THE FOCUS OF OUR ATTENTION IS CENTERED ON THE ANALYSIS OF THE PUBLISHED DATA ON THE DIFFERENTIAL METHYLATION OF DNA FROM VARIOUS BIOLOGICAL SAMPLES OF MS PATIENTS OBTAINED USING BOTH THE CANDIDATE GENE APPROACH AND HIGH-THROUGHPUT METHODS. 2021 12 4228 25 METHYLATION OF INFLAMMATORY CELLS IN LUNG DISEASES. THIS CHAPTER OVERVIEWS ROLES OF DNA METHYLATION IN INFLAMMATORY CELL BIOLOGY WITH THE FOCUSES ON LYMPHOCYTES AND MACROPHAGES/MONOCYTES IN LUNG DISEASES, ALTHOUGH THE MOLECULAR MECHANISMS BY WHICH TARGET GENES ARE METHYLATED AND REGULATED IN LUNG DISEASES REMAIN UNCLEAR. MOST OF EPIGENETIC STUDIES ON DNA METHYLATION OF TARGET GENES IN LUNG DISEASES MAINLY DEMONSTRATED THE CORRELATION OF DNA METHYLATION OF TARGET GENES WITH THE LEVELS OF OTHER CORRESPONDING FACTORS, WITH THE SPECIFICITY OF CLINICAL PHENOMES, AND WITH THE SEVERITY OF LUNG DISEASES. THERE IS AN URGENT NEED TO IDENTIFY AND VALIDATE THE SPECIFICITY AND REGULATORY MECHANISMS OF INFLAMMATORY CELL EPIGENETICS IN DEPTH. THE EPIGENETIC HETEROGENEITY AMONG DIFFERENT SUBSETS OF T CELLS AND AMONG PROMOTERS OR NON-PROMOTERS OF TARGET GENES SHOULD BE FURTHERMORE CLARIFIED IN ACUTE OR CHRONIC LUNG DISEASES AND CANCERS. THE HYPER/HYPO-METHYLATION AND MODIFICATIONS OF CHROMOSOL AND EXTRACHROMOSOMAL DNA MAY RESULT IN ALTERNATIONS IN PROTEINS WITHIN INFLAMMATORY CELLS, WHICH CAN BE IDENTIFIED AS DISEASE-SPECIFIC BIOMARKERS AND THERAPEUTIC TARGETS. 2020 13 2017 39 EPIGENETIC BIOMARKERS IN RHEUMATOLOGY - THE FUTURE? EPIGENETIC CHANGES ARE STABLE MODIFICATIONS OF DNA OR HISTONES THAT PROFOUNDLY ALTER GENE EXPRESSION. THEY CAN BE CHANGED BY ENVIRONMENTAL INFLUENCES AND CAN THEN BE PASSED ON TO DAUGHTER CELLS OR VIA THE GERM LINE TO OFFSPRING. A VARIETY OF CHANGES IN EPIGENETIC MARKS AND IN THE EXPRESSION OF NONCODING RNA HAS BEEN FOUND IN CANCER AS WELL AS IN CHRONIC INFLAMMATORY DISEASES. INTERESTINGLY, IN BOTH DISEASES SIMILAR MECHANISMS AND PATHWAYS ARE AFFECTED ALBEIT OFTEN TO A DIFFERENT EXTENT. DNA METHYLATION IS OFTEN LOST IN REPETITIVE SEQUENCES, WHILE IN PROMOTER REGIONS HYPO- AS WELL AS HYPERMETHYLATION IS FOUND. CHANGES IN MICRORNA LEVELS TYPICALLY AFFECT MICRORNAS THAT ARE CHANGED BY AN INFLAMMATORY ENVIRONMENT, BUT DISEASE SPECIFIC CHANGES HAVE ALSO BEEN FOUND IN THE BLOOD AND VARIOUS CELL TYPES OF PATIENTS WITH RHEUMATOID ARTHRITIS, SYSTEMIC LUPUS ERYTHEMATOSUS AND OTHER RHEUMATIC DISEASES. THEREFORE, CHANGES IN THE EXPRESSION OF MICRORNA IN PARTICULAR, BUT ALSO DEMETHYLATED GENE LOCI, HAVE BEEN PROPOSED AS POTENTIAL BIOMARKERS IN CHRONIC INFLAMMATORY DISEASES AND IN CANCER. POTENTIALLY, THESE CHANGES COULD BE USED FOR EARLY DIAGNOSIS AND ALSO TO PREDICT TREATMENT RESPONSE. UNFORTUNATELY MOST STUDIES IN RHEUMATOLOGY UP TO NOW WERE NOT DESIGNED TO VALIDATE THESE EPIGENETIC CHANGES AS BIOMARKERS. SINCE THE CANCER FIELD IS MUCH MORE ADVANCED IN THE USAGE OF BIOMARKERS FOR DISEASE SUBCLASSIFICATIONS AND SUBSEQUENT THERAPEUTIC DECISIONS, IT IS WORTHWHILE TO TAKE A CLOSER LOOK AT THE BIOMARKERS, METHODS AND PROCEDURES USED IN ONCOLOGY AND TO SEE WHICH OF THESE COULD ALSO BE APPLIED TO PREDICTING DISEASE SEVERITY AND THERAPEUTIC RESPONSE IN RHEUMATIC DISEASES. THIS ARTICLE WILL HIGHLIGHT COMMON EPIGENETIC PATHWAYS ACTIVATED IN CANCER AND VARIOUS RHEUMATIC DISEASES AND SUMMARISE EPIGENETIC CHANGES THAT HAVE THE POTENTIAL TO BECOME BIOMARKERS IN RHEUMATIC DISEASES. 2016 14 287 24 AGING AND CHRONIC SUN EXPOSURE CAUSE DISTINCT EPIGENETIC CHANGES IN HUMAN SKIN. EPIGENETIC CHANGES ARE WIDELY CONSIDERED TO PLAY AN IMPORTANT ROLE IN AGING, BUT EXPERIMENTAL EVIDENCE TO SUPPORT THIS HYPOTHESIS HAS BEEN SCARCE. WE HAVE USED ARRAY-BASED ANALYSIS TO DETERMINE GENOME-SCALE DNA METHYLATION PATTERNS FROM HUMAN SKIN SAMPLES AND TO INVESTIGATE THE EFFECTS OF AGING, CHRONIC SUN EXPOSURE, AND TISSUE VARIATION. OUR RESULTS REVEAL A HIGH DEGREE OF TISSUE SPECIFICITY IN THE METHYLATION PATTERNS AND ALSO SHOWED VERY LITTLE INTERINDIVIDUAL VARIATION WITHIN TISSUES. DATA STRATIFICATION BY AGE REVEALED THAT DNA FROM OLDER INDIVIDUALS WAS CHARACTERIZED BY A SPECIFIC HYPERMETHYLATION PATTERN AFFECTING LESS THAN 1% OF THE MARKERS ANALYZED. INTERESTINGLY, STRATIFICATION BY SUN EXPOSURE PRODUCED A FUNDAMENTALLY DIFFERENT PATTERN WITH A SIGNIFICANT TREND TOWARDS HYPOMETHYLATION. OUR RESULTS THUS IDENTIFY DEFINED AGE-RELATED DNA METHYLATION CHANGES AND SUGGEST THAT THESE ALTERATIONS MIGHT CONTRIBUTE TO THE PHENOTYPIC CHANGES ASSOCIATED WITH SKIN AGING. 2010 15 3027 38 GENETICS OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) IS A COMPLEX DISEASE WITH MULTIFACTORIAL BACKGROUND, BASED ON THE INTERACTION OF ENVIRONMENTAL AND GENETIC FACTORS. ENVIRONMENTAL FACTORS ARE CLEARLY RELATED TO THE DEVELOPMENT OF THE DISEASE. HOWEVER, FAMILY AND TWIN STUDIES SUGGESTED GENETICS FACTORS TO BE ONE OF THE IMPORTANT DETERMINANTS FOR THE DEVELOPMENT OF COPD. DIFFERENT APPROACHES HAVE BEEN USED TO IDENTIFY GENES OF INTEREST. GENOMEWIDE LINKAGE ANALYSIS FOUND AREAS OF INTEREST ON DIFFERENT CHROMOSOMES, WITH SOME GENES LOCATED IN THIS REGIONS BEING IDENTIFIED AND REPLICATED AS SUSCEPTIBILITY GENES. NUMEROUS OF CANDIDATE GENES THAT COULD BE LINKED TO DISEASE PATHOGENESIS HAVE BEEN IMPLICATED IN COPD GENETICS. HOWEVER, THE CANDIDATE GENE APPROACH IS OFTEN LIMITED BY INCONSISTENT RESULTS IN OTHER STUDY POPULATIONS. RECENTLY, A COMBINATION OF DIFFERENT METHODS IS USED GIVING MORE EVIDENCE FOR SOME CANDIDATE GENES, INCLUDING TGFBETA-1, SURFACTANT, SERPINE2 AND MICROSOMAL EPOXIDE HYDROLASE. IN THE FUTURE ONGOING EXACT PHENOTYPE DEFINITION, COMBINATION OF SEVERAL APPROACHES, GENOME-WIDE ASSOCIATION STUDIES AND ANIMAL MODEL GENETICS WILL LEAD TO NEW INSIGHTS INTO THE GENETICS OF COPD, WITH EPIGENETIC FACTORS NEEDS TO BE FURTHER INVESTIGATED AND CONSIDERED IN CONCERT WITH GENETIC FINDINGS. 2007 16 2483 31 EPIGENETIC VARIATION AND HUMAN DISEASE. CYTOSINE GUANINE DINUCLEOTIDE (CPG) ISLAND METHYLATION IS A KNOWN MECHANISM OF EPIGENETIC INHERITANCE IN POSTMEIOTIC CELLS. THROUGH ASSOCIATED CHROMATIN CHANGES AND SILENCING, SUCH EPIGENETIC STATES CAN INFLUENCE CELLULAR PHYSIOLOGY AND AFFECT DISEASE RISK AND SEVERITY. OUR STUDIES OF CPG ISLAND METHYLATION IN NORMAL COLORECTAL MUCOSA REVEALED PROGRESSIVE AGE-RELATED INCREASES AT MULTIPLE GENE LOCI, SUGGESTING GENOME-WIDE MOLECULAR ALTERATIONS WITH POTENTIAL TO SILENCE GENE EXPRESSION. HOWEVER, THERE WAS CONSIDERABLE VARIATION IN THE DEGREE OF METHYLATION AMONG INDIVIDUALS OF COMPARABLE AGES. SUCH VARIATION COULD BE RELATED TO GENETIC FACTORS, LIFESTYLE, OR ENVIRONMENTAL EXPOSURES. STUDIES IN ULCERATIVE COLITIS AND HEPATOCELLULAR CIRRHOSIS AND NEOPLASIA REVEALED THAT CHRONIC INFLAMMATORY STATES ARE ACCOMPANIED BY MARKED INCREASES IN CPG ISLAND METHYLATION IN NORMAL-APPEARING TISSUES, CONFIRMING THE HYPOTHESIS THAT PROINFLAMMATORY EXPOSURES COULD ACCOUNT FOR PART OF THE EPIGENETIC VARIATION IN HUMAN POPULATIONS. PRELIMINARY DATA ALSO SUGGEST POTENTIAL INFLUENCES OF LIFESTYLE AND EXPOSURE FACTORS ON CPG ISLAND METHYLATION. IT IS SUGGESTED THAT EPIGENETIC VARIATION RELATED TO AGING, LIFESTYLE, EXPOSURES AND POSSIBLY GENETIC FACTORS, IS ONE OF THE MODULATORS OF ACQUIRED, AGE-RELATED HUMAN DISEASES, INCLUDING NEOPLASIA. 2002 17 3503 24 IDENTIFICATION OF POTENTIAL DIFFERENTIALLY METHYLATED GENE-RELATED BIOMARKERS IN ENDOMETRIOSIS. AIM: TO IDENTIFY EPIGENETIC ALTERATIONS OF DIFFERENTIALLY EXPRESSED GENES AND SCREEN OUT TARGETED THERAPEUTIC DRUGS IN ENDOMETRIOSIS. METHODS: BASED ON THE GENE EXPRESSION OMNIBUS DATABASE AND A SERIES OF BIOLOGICAL INFORMATION ANALYSIS TOOLS, SUPPLEMENTED BY VALIDATION OF CLINICAL SAMPLES, ABERRANT DNA METHYLATION-DRIVEN GENES AND THEIR FUNCTIONS WERE EXPLORED, AS WELL AS POSSIBLE TARGETED DRUGS. RESULTS: THIS STUDY SCREENED OUT A RANGE OF DNA METHYLATION-DRIVEN GENES THAT WERE ASSOCIATED WITH POWERFUL PROPERTIES AND CORRESPONDING PATHWAYS. AMONG THEM, BDNF AND CCL2 WERE KEY GENES IN THE DEVELOPMENT OF ENDOMETRIOSIS. FOUR CHEMICAL AGENTS HAVE BEEN FLAGGED AS POTENTIAL TREATMENTS FOR ENDOMETRIOSIS. CONCLUSION: THESE CANDIDATE GENES AND SMALL-MOLECULE AGENTS MAY BE FURTHER EXPLORED AS POTENTIAL TARGETS AND DRUGS FOR ENDOMETRIOSIS DIAGNOSIS AND THERAPY, RESPECTIVELY. 2022 18 6013 40 THE APPLICATIONS OF DNA METHYLATION AS A BIOMARKER IN KIDNEY TRANSPLANTATION: A SYSTEMATIC REVIEW. BACKGROUND: ALTHOUGH KIDNEY TRANSPLANTATION IMPROVES PATIENT SURVIVAL AND QUALITY OF LIFE, LONG-TERM RESULTS ARE HAMPERED BY BOTH IMMUNE- AND NON-IMMUNE-MEDIATED COMPLICATIONS. CURRENT BIOMARKERS OF POST-TRANSPLANT COMPLICATIONS, SUCH AS ALLOGRAFT REJECTION, CHRONIC RENAL ALLOGRAFT DYSFUNCTION, AND CUTANEOUS SQUAMOUS CELL CARCINOMA, HAVE A SUBOPTIMAL PREDICTIVE VALUE. DNA METHYLATION IS AN EPIGENETIC MODIFICATION THAT DIRECTLY AFFECTS GENE EXPRESSION AND PLAYS AN IMPORTANT ROLE IN PROCESSES SUCH AS ISCHEMIA/REPERFUSION INJURY, FIBROSIS, AND ALLOREACTIVE IMMUNE RESPONSE. NOVEL TECHNIQUES CAN QUICKLY ASSESS THE DNA METHYLATION STATUS OF MULTIPLE LOCI IN DIFFERENT CELL TYPES, ALLOWING A DEEP AND INTERESTING STUDY OF CELLS' ACTIVITY AND FUNCTION. THEREFORE, DNA METHYLATION HAS THE POTENTIAL TO BECOME AN IMPORTANT BIOMARKER FOR PREDICTION AND MONITORING IN KIDNEY TRANSPLANTATION. PURPOSE OF THE STUDY: THE AIM OF THIS STUDY WAS TO EVALUATE THE ROLE OF DNA METHYLATION AS A POTENTIAL BIOMARKER OF GRAFT SURVIVAL AND COMPLICATIONS DEVELOPMENT IN KIDNEY TRANSPLANTATION. MATERIAL AND METHODS: A SYSTEMATIC REVIEW OF SEVERAL DATABASES HAS BEEN CONDUCTED. THE NEWCASTLE-OTTAWA SCALE AND THE JADAD SCALE HAVE BEEN USED TO ASSESS THE RISK OF BIAS FOR OBSERVATIONAL AND RANDOMIZED STUDIES, RESPECTIVELY. RESULTS: TWENTY ARTICLES REPORTING ON DNA METHYLATION AS A BIOMARKER FOR KIDNEY TRANSPLANTATION WERE INCLUDED, ALL USING DNA METHYLATION FOR PREDICTION AND MONITORING. DNA METHYLATION PATTERN ALTERATIONS IN CELLS ISOLATED FROM DIFFERENT TISSUES, SUCH AS KIDNEY BIOPSIES, URINE, AND BLOOD, HAVE BEEN ASSOCIATED WITH ISCHEMIA-REPERFUSION INJURY AND CHRONIC RENAL ALLOGRAFT DYSFUNCTION. THESE ALTERATIONS OCCURRED IN DIFFERENT AND SPECIFIC LOCI. DNA METHYLATION STATUS HAS ALSO PROVED TO BE IMPORTANT FOR IMMUNE RESPONSE MODULATION, HAVING A CRUCIAL ROLE IN REGULATORY T CELL DEFINITION AND ACTIVITY. RESEARCH ALSO FOCUSED ON A BETTER UNDERSTANDING OF THE ROLE OF THIS EPIGENETIC MODIFICATION ASSESSMENT FOR REGULATORY T CELLS ISOLATION AND EXPANSION FOR FUTURE TOLERANCE INDUCTION-ORIENTED THERAPIES. CONCLUSIONS: STUDIES INCLUDED IN THIS REVIEW ARE HETEROGENEOUS IN STUDY DESIGN, BIOLOGICAL SAMPLES, AND OUTCOME. MORE COORDINATED INVESTIGATIONS ARE NEEDED TO AFFIRM DNA METHYLATION AS A CLINICALLY RELEVANT BIOMARKER IMPORTANT FOR PREVENTION, MONITORING, AND INTERVENTION. 2022 19 6790 26 [DNA METHYLATION ANALYSIS IN ENVIRONMENTAL AND OCCUPATIONAL CANCER RESEARCH]. THE PRESENT PAPER REVIEWS RECENT LABORATORY METHODS AND EXPERIMENTAL EVIDENCE CONCERNING EPIGENETIC BIOMARKERS INVOLVED IN CARCINOGENESIS MECHANISMS. WE INTRODUCE DNA METHYLATION AND ITS ROLE IN GENE EXPRESSION CONTROL. DNA METHYLATION ANALYSIS MAY ALLOW TO IDENTIFY EARLY CHANGES LEADING TO CANCER AND OTHER CHRONIC DISEASES. WE DESCRIBE HERE STRATEGIES FOR LABORATORY ANALYSES AND THEIR POSSIBLE APPLICATIONS. WE EXAMINE RESULTS FROM RECENT EXPERIMENTAL STUDIES SUGGESTING THAT THE EFFECTS OF CERTAIN OCCUPATIONAL AGENTS ARE MEDIATED BY ALTERATIONS IN DNA METHYLATION. PLANNING AND CONDUCTING INVESTIGATIONS ON EXPOSED HUMAN SUBJECTS WILL ALLOW TO VERIFY WHETHER DNA METHYLATION CHANGES IDENTIFIED IN ANIMAL AND IN-VITRO STUDIES MAY BE USED AS EARLY-EFFECT AND SUSCEPTIBILITY BIOMARKERS. DNA METHYLATION ANALYSIS HAS THE POTENTIAL FOR FUTURE APPLICATIONS IN RISK ASSESSMENT AND PREVENTION PROGRAMS CONDUCTED ON SUBJECTS EXPOSED TO HUMAN CARCINOGENS. 2005 20 1844 37 EFFECTS OF THE LIFESTYLE HABITS IN BREAST CANCER TRANSCRIPTIONAL REGULATION. THROUGH RESEARCH CARRIED OUT IN THE LAST 25 YEARS ABOUT THE BREAST CANCER ETIOLOGY, IT HAS BEEN POSSIBLE TO ESTIMATE THAT LESS THAN 10 % OF PATIENTS WHO ARE DIAGNOSED WITH THE CONDITION ARE CARRIERS OF SOME GERMLINE OR SOMATIC MUTATION. THE CLINICAL REPORTS OF BREAST CANCER PATIENTS WITH HEALTHY TWINS AND THE DEVELOPMENT OF DISEASE IN WOMEN WITHOUT HIGH PENETRANCE MUTATIONS DETECTED, WARN THE PARTICIPATION MORE FACTORS IN THE TRANSFORMATION PROCESS. THE HIGH INCIDENCE OF MAMMARY ADENOCARCINOMA IN THE MODERN WOMAN AND THE URGENT NEED FOR NEW METHODS OF PREVENTION AND EARLY DETECTION HAVE DEMANDED MORE INFORMATION ABOUT THE ROLE THAT ENVIRONMENT AND LIFESTYLE HAVE ON THE TRANSFORMATION OF MAMMARY GLAND EPITHELIAL CELLS. OBESITY, ALCOHOLISM AND SMOKING ARE FACTORS THAT HAVE SHOWN A CLOSE CORRELATION WITH THE RISK OF DEVELOPING BREAST CANCER. AND ALTHOUGH THESE CONDITIONS AFFECT DIFFERENT CELL REGULATION LEVELS, THE STUDY OF ITS EFFECTS IN THE MECHANISMS OF TRANSCRIPTIONAL AND EPIGENETIC REGULATION IS CONSIDERED CRITICAL FOR A BETTER UNDERSTANDING OF THE LOSS OF IDENTITY OF EPITHELIAL CELLS DURING CARCINOGENESIS OF THIS TISSUE. THE MAIN OBJECTIVE OF THIS REVIEW WAS TO ESTABLISH THE IMPORTANCE OF CHANGES OCCURRING TO TRANSCRIPTIONAL LEVEL IN THE MAMMARY GLAND AS A CONSEQUENCE OF ACUTE OR CHRONIC EXPOSURE TO HARMFUL PRODUCTS SUCH AS OBESITY-CAUSING FOODS, ETHANOL AND CIGARETTE SMOKE COMPONENTS. AT ANALYZE THE MAIN STUDIES RELATED TO TOPIC, IT HAS CONCLUDED THAT THE UNDERSTANDING OF EFFECTS CAUSED BY THE LIFESTYLE FACTORS IN PERFORMANCE OF THE TRANSCRIPTIONAL MECHANISMS THAT DETERMINE GENE EXPRESSION OF THE MAMMARY GLAND EPITHELIAL CELLS, MAY HELP EXPLAIN THE DEVELOPMENT OF THIS DISEASE IN WOMEN WITHOUT GENETIC PROPENSITY AND DIFFERENT PHENOTYPIC MANIFESTATIONS OF THIS CANCER TYPE. 2016