1 1917 134 ENVIRONMENTAL ARSENIC EXPOSURE: FROM GENETIC SUSCEPTIBILITY TO PATHOGENESIS. MORE THAN 200 MILLION PEOPLE IN 70 COUNTRIES ARE EXPOSED TO ARSENIC THROUGH DRINKING WATER. CHRONIC EXPOSURE TO THIS METALLOID HAS BEEN ASSOCIATED WITH THE ONSET OF MANY DISEASES, INCLUDING CANCER. EPIDEMIOLOGICAL EVIDENCE SUPPORTS ITS CARCINOGENIC POTENTIAL, HOWEVER, DETAILED MOLECULAR MECHANISMS REMAIN TO BE ELUCIDATED. DESPITE THE GLOBAL MAGNITUDE OF THIS PROBLEM, NOT ALL INDIVIDUALS FACE THE SAME RISK. SUSCEPTIBILITY TO THE TOXIC EFFECTS OF ARSENIC IS INFLUENCED BY ALTERATIONS IN GENES INVOLVED IN ARSENIC METABOLISM, AS WELL AS BIOLOGICAL FACTORS, SUCH AS AGE, GENDER AND NUTRITION. MOREOVER, CHRONIC ARSENIC EXPOSURE RESULTS IN SEVERAL GENOTOXIC AND EPIGENETIC ALTERATIONS TIGHTLY ASSOCIATED WITH THE ARSENIC BIOTRANSFORMATION PROCESS, RESULTING IN AN INCREASED CANCER RISK. IN THIS REVIEW, WE: 1) REVIEW THE ROLES OF INTER-INDIVIDUAL DNA-LEVEL VARIATIONS INFLUENCING THE SUSCEPTIBILITY TO ARSENIC-INDUCED CARCINOGENESIS; 2) DISCUSS THE CONTRIBUTION OF ARSENIC BIOTRANSFORMATION TO CANCER INITIATION; 3) PROVIDE INSIGHTS INTO EMERGING RESEARCH AREAS AND THE CHALLENGES IN THE FIELD; AND 4) COMPILE A RESOURCE OF PUBLICLY AVAILABLE ARSENIC-RELATED DNA-LEVEL VARIATIONS, TRANSCRIPTOME AND METHYLATION DATA. UNDERSTANDING THE MOLECULAR MECHANISMS OF ARSENIC EXPOSURE AND ITS SUBSEQUENT HEALTH EFFECTS WILL SUPPORT EFFORTS TO REDUCE THE WORLDWIDE HEALTH BURDEN AND ENCOURAGE THE DEVELOPMENT OF STRATEGIES FOR MANAGING ARSENIC-RELATED DISEASES IN THE ERA OF PERSONALIZED MEDICINE. 2018 2 5361 42 RECENT ADVANCES IN ARSENIC RESEARCH: SIGNIFICANCE OF DIFFERENTIAL SUSCEPTIBILITY AND SUSTAINABLE STRATEGIES FOR MITIGATION. ARSENIC CONTAMINATION IN DRINKING WATER AND ASSOCIATED ADVERSE OUTCOMES ARE ONE OF THE MAJOR HEALTH ISSUES IN MORE THAN 50 COUNTRIES WORLDWIDE. THE SCENARIO IS GETTING EVEN MORE DETRIMENTAL WITH INCREASING NUMBER OF AFFECTED PEOPLE AND NEWER SITES REPORTED FROM ALL OVER THE WORLD. APART FROM DRINKING WATER, THE PRESENCE OF ARSENIC HAS BEEN FOUND IN VARIOUS OTHER DIETARY SOURCES. CHRONIC ARSENIC TOXICITY AFFECTS MULTIPLE PHYSIOLOGICAL SYSTEMS AND MAY CAUSE MALIGNANCIES LEADING TO DEATH. EXPOSED INDIVIDUALS, RESIDING IN THE SAME AREA, DEVELOPED DIFFERENTIAL DERMATOLOGICAL LESION PHENOTYPES AND VARIED SUSCEPTIBILITY TOWARD VARIOUS OTHER ARSENIC-INDUCED DISEASE RISK, EVEN AFTER CONSUMING EQUIVALENT AMOUNT OF ARSENIC FROM THE SIMILAR SOURCE, OVER THE SAME DURATION OF TIME. RESEARCHES SO FAR INDICATE THAT DIFFERENTIAL SUSCEPTIBILITY PLAYS AN IMPORTANT ROLE IN ARSENIC-INDUCED DISEASE MANIFESTATION. IN THIS COMPREHENSIVE REVIEW, WE HAVE IDENTIFIED MAJOR POPULATION-BASED STUDIES OF THE LAST 20 YEARS, INDICATING POSSIBLE CAUSES OF DIFFERENTIAL SUSCEPTIBILITY EMPHASIZING ARSENIC METHYLATION CAPACITY, VARIATION IN HOST GENOME (SINGLE NUCLEOTIDE POLYMORPHISM), AND INDIVIDUAL EPIGENETIC PATTERN (DNA METHYLATION, HISTONE MODIFICATION, AND MIRNA EXPRESSION). HOLISTIC MULTIDISCIPLINARY STRATEGIES NEED TO BE IMPLEMENTED WITH FEW SUSTAINABLE YET COST-EFFECTIVE SOLUTIONS LIKE ALTERNATIVE WATER SOURCE, TREATMENT OF ARSENIC-CONTAMINATED WATER, NEW ADAPTATIONS IN IRRIGATION SYSTEM, SIMPLE MODIFICATIONS IN COOKING STRATEGY, AND DIETARY SUPPLEMENTATIONS TO COMBAT THIS MENACE. OUR REVIEW FOCUSES ON THE PRESENT PERSPECTIVES OF ARSENIC RESEARCH WITH SPECIAL EMPHASIS ON THE PROBABLE CAUSES OF DIFFERENTIAL SUSCEPTIBILITY TOWARD CHRONIC ARSENIC TOXICITY AND SUSTAINABLE REMEDIATION STRATEGIES. 2020 3 3210 50 HEALTH EFFECTS ASSOCIATED WITH PRE- AND PERINATAL EXPOSURE TO ARSENIC. INORGANIC ARSENIC IS A WELL-ESTABLISHED HUMAN CARCINOGEN, ABLE TO INDUCE GENETIC AND EPIGENETIC ALTERATIONS. MORE THAN 200 MILLION PEOPLE WORLDWIDE ARE EXPOSED TO ARSENIC CONCENTRATIONS IN DRINKING WATER EXCEEDING THE RECOMMENDED WHO THRESHOLD (10MUG/L). ADDITIONALLY, CHRONIC EXPOSURE TO LEVELS BELOW THIS THRESHOLD IS KNOWN TO RESULT IN LONG-TERM HEALTH EFFECTS IN HUMANS. THE ARSENIC-RELATED HEALTH EFFECTS IN HUMANS ARE ASSOCIATED WITH ITS BIOTRANSFORMATION PROCESS, WHEREBY THE RESULTING METABOLITES CAN INDUCE MOLECULAR DAMAGE THAT ACCUMULATES OVER TIME. THE EFFECTS DERIVED FROM THESE ALTERATIONS INCLUDE GENOMIC INSTABILITY ASSOCIATED WITH OXIDATIVE DAMAGE, ALTERATION OF GENE EXPRESSION (INCLUDING CODING AND NON-CODING RNAS), GLOBAL AND LOCALIZED EPIGENETIC REPROGRAMMING, AND HISTONE POSTTRANSLATIONAL MODIFICATIONS. THESE ALTERATIONS DIRECTLY AFFECT MOLECULAR PATHWAYS INVOLVED IN THE ONSET AND PROGRESSION OF MANY CONDITIONS THAT CAN ARISE EVEN DECADES AFTER THE EXPOSURE OCCURS. IMPORTANTLY, ARSENIC METABOLITES GENERATED DURING ITS BIOTRANSFORMATION CAN ALSO PASS THROUGH THE PLACENTAL BARRIER, RESULTING IN FETAL EXPOSURE TO THIS CARCINOGEN AT SIMILAR LEVELS TO THOSE OF THE MOTHER. AS SUCH, MORE IMMEDIATE EFFECTS OF THE ARSENIC-INDUCED MOLECULAR DAMAGE CAN BE OBSERVED AS DETRIMENTAL EFFECTS ON FETAL DEVELOPMENT, PREGNANCY, AND BIRTH OUTCOMES. IN THIS REVIEW, WE FOCUS ON THE GENETIC AND EPIGENETIC DAMAGE ASSOCIATED WITH EXPOSURE TO LOW LEVELS OF ARSENIC, PARTICULARLY THOSE AFFECTING EARLY DEVELOPMENTAL STAGES. WE ALSO PRESENT HOW THESE ALTERATIONS OCCURRING DURING EARLY LIFE CAN IMPACT THE DEVELOPMENT OF CERTAIN DISEASES IN ADULT LIFE. 2021 4 2655 53 EPIMUTAGENESIS: A PROSPECTIVE MECHANISM TO REMEDIATE ARSENIC-INDUCED TOXICITY. ARSENIC TOXICITY IS A GLOBAL ISSUE, ADDRESSED BY THE WORLD HEALTH ORGANIZATION AS ONE OF THE MAJOR NATURAL CALAMITIES FACED BY HUMANS. MORE THAN 137 MILLION INDIVIDUALS IN 70 NATIONS ARE AFFECTED BY ARSENIC MAINLY THROUGH DRINKING WATER AND ALSO THROUGH DIET. CHRONIC ARSENIC EXPOSURE LEADS TO VARIOUS TYPES OF PATHO-PHYSIOLOGICAL END POINTS IN HUMANS INCLUDING CANCERS. ARSENIC, A XENOBIOTIC SUBSTANCE, IS BIOTRANSFORMED IN THE BODY TO ITS METHYLATED SPECIES BY USING THE PHYSIOLOGICAL S-ADENOSYL METHIONINE (SAM). SAM DICTATES METHYLATION STATUS OF THE GENOME AND ARSENIC METABOLISM LEADS TO DEPLETION OF SAM LEADING TO AN EPIGENETIC DISEQUILIBRIUM. SINCE EPIGENETICS IS ONE OF THE MAJOR PHENOMENON AT THE INTERFACE BETWEEN THE ENVIRONMENT AND HUMAN HEALTH IMPACT, ITS DISEQUILIBRIUM BY ARSENIC INFLICTS UPON THE CHROMATIN COMPACTION, GENE EXPRESSION, GENOMIC STABILITY AND A HOST OF BIOMOLECULAR INTERACTIONS, THE INTERACTOME WITHIN THE CELL. SINCE ARSENIC IS NOT MUTAGENIC BUT IS CARCINOGENIC IN NATURE, ARSENIC INDUCED EPIMUTAGENESIS HAS COME TO THE FOREFRONT SINCE IT DETERMINES THE TRANSCRIPTIONAL AND GENOMIC INTEGRITY OF THE CELL. ARSENIC TOXICITY BRINGS FORTH SEVERAL PATHOPHYSIOLOGICAL MANIFESTATIONS LIKE DERMATOLOGICAL NON-CANCEROUS, PRE-CANCEROUS AND CANCEROUS LESIONS, PERIPHERAL NEUROPATHY, DNA DAMAGE, RESPIRATORY DISORDERS AND CANCERS OF SEVERAL INTERNAL ORGANS. RECENTLY, SEVERAL DISEASES OF SIMILAR MANIFESTATIONS HAVE BEEN EXPLAINED WITH THE RELEVANT EPIGENETIC PERSPECTIVES REGARDING THE POSSIBLE MOLECULAR MECHANISM FOR THEIR ONSET. HENCE, IN THE CURRENT REVIEW, WE COMPREHENSIVELY TRY TO INTERCALATE THE INFORMATION ON ARSENIC-INDUCED EPIGENETIC ALTERATIONS OF DNA, HISTONES AND MICRORNA SO AS TO UNDERSTAND WHETHER THE ARSENIC-INDUCED TOXIC MANIFESTATIONS ARE BROUGHT ABOUT BY THE EPIGENETIC CHANGES. WE HIGHLIGHT THE NEED TO UNDERSTAND THE ASPECT OF EPIMUTAGENESIS AND SUBSEQUENT ALTERATIONS IN THE CELLULAR INTERACTOME DUE TO ARSENIC-INDUCED MOLECULAR CHANGES, WHICH MAY BE UTILIZED TO DEVELOP PUTATIVE THERAPEUTIC STRATEGIES TARGETING BOTH OXIDATIVE POTENTIAL AND EPIMUTAGENESIS IN HUMANS. 2015 5 633 37 BIOLOGICAL EFFECTS AND EPIDEMIOLOGICAL CONSEQUENCES OF ARSENIC EXPOSURE, AND REAGENTS THAT CAN AMELIORATE ARSENIC DAMAGE IN VIVO. THROUGH CONTAMINATED DIET, WATER, AND OTHER FORMS OF ENVIRONMENTAL EXPOSURE, ARSENIC AFFECTS HUMAN HEALTH. THERE ARE MANY U.S. AND WORLDWIDE "HOT SPOTS" WHERE THE ARSENIC LEVEL IN PUBLIC WATER EXCEEDS THE MAXIMUM EXPOSURE LIMIT. THE BIOLOGICAL EFFECTS OF CHRONIC ARSENIC EXPOSURE INCLUDE GENERATION OF REACTIVE OXYGEN SPECIES (ROS), LEADING TO OXIDATIVE STRESS AND DNA DAMAGE, EPIGENETIC DNA MODIFICATION, INDUCTION OF GENOMIC INSTABILITY, AND INFLAMMATION AND IMMUNOMODULATION, ALL OF WHICH CAN INITIATE CARCINOGENESIS. HIGH ARSENIC EXPOSURE IS EPIDEMIOLOGICALLY ASSOCIATED WITH SKIN, LUNG, BLADDER, LIVER, KIDNEY AND PANCREATIC CANCER, AND CARDIOVASCULAR, NEURONAL, AND OTHER DISEASES. THIS REVIEW BRIEFLY SUMMARIZES THE BIOLOGICAL EFFECTS OF ARSENIC EXPOSURE AND EPIDEMIOLOGICAL CANCER STUDIES WORLDWIDE, AND PROVIDES AN OVERVIEW FOR EMERGING RODENT-BASED STUDIES OF REAGENTS THAT CAN AMELIORATE THE EFFECTS OF ARSENIC EXPOSURE IN VIVO. THESE REAGENTS MAY BE TRANSLATED TO HUMAN POPULATIONS FOR DISEASE PREVENTION. WE PROPOSE THE IMPORTANCE OF DEVELOPING A BIOMARKER-BASED PRECISION PREVENTION APPROACH FOR THE HEALTH ISSUES ASSOCIATED WITH ARSENIC EXPOSURE THAT AFFECTS MILLIONS OF PEOPLE WORLDWIDE. 2017 6 480 41 ARSENIC-INDUCED CARCINOGENESIS: THE IMPACT OF MIRNA DYSREGULATION. ARSENIC IS A TOXIC METALLOID WIDELY PRESENT IN THE EARTH'S CRUST, AND IS A PROVEN HUMAN CARCINOGEN. CHRONIC ARSENIC EXPOSURE MAINLY THROUGH DRINKING WATER CAUSES SKIN, LUNG, AND URINARY BLADDER CANCERS, AND IS ASSOCIATED WITH LIVER, PROSTATE, AND KIDNEY CANCERS, CARDIOVASCULAR AND NEUROLOGICAL DISORDERS, AND DIABETES. SEVERAL MODES OF ACTION HAVE BEEN SUGGESTED IN ARSENIC CARCINOGENESIS. HOWEVER, THE MOLECULAR ETIOLOGY OF ARSENIC-INDUCED CANCER REMAINS UNCLEAR. RECENT EVIDENCE CLEARLY INDICATES THAT GENE EXPRESSION MODIFICATIONS INDUCED BY ARSENIC MAY INVOLVE EPIGENETIC ALTERATIONS, INCLUDING MIRNA DYSREGULATION. MANY MIRNAS HAVE BEEN IMPLICATED IN DIFFERENT HUMAN CANCERS AS A CONSEQUENCE OF LOSSES AND OR GAINS OF MIRNA FUNCTION THAT CONTRIBUTE TO CANCER DEVELOPMENT. PROGRESS IN IDENTIFYING MIRNA DYSREGULATION INDUCED BY ARSENIC HAS BEEN MADE USING DIFFERENT APPROACHES AND MODELS. THE PRESENT REVIEW DISCUSSES THE RECENT DATA REGARDING DYSREGULATED EXPRESSION OF MIRNA IN ARSENIC-INDUCED MALIGNANT TRANSFORMATION IN VITRO, GAPS IN CURRENT UNDERSTANDING AND DEFICIENCIES IN CURRENT MODELS FOR ARSENIC-INDUCED CARCINOGENESIS, AND FUTURE DIRECTIONS OF RESEARCH THAT WOULD IMPROVE OUR KNOWLEDGE REGARDING THE MECHANISMS INVOLVED IN ARSENIC-INDUCED CARCINOGENESIS. 2018 7 396 35 AN UPDATE ON EPIGENETICS AND CHILDHOOD RESPIRATORY DISEASES. EPIGENETIC MECHANISMS, DEFINED AS CHANGES IN PHENOTYPE OR GENE EXPRESSION CAUSED BY MECHANISMS OTHER THAN CHANGES IN THE UNDERLYING DNA SEQUENCE, HAVE BEEN PROPOSED TO CONSTITUTE A LINK BETWEEN GENETIC AND ENVIRONMENTAL FACTORS THAT AFFECT COMPLEX DISEASES. RECENT STUDIES SHOW THAT DNA METHYLATION, ONE OF THE KEY EPIGENETIC MECHANISMS, IS ALTERED IN CHILDREN EXPOSED TO AIR POLLUTANTS AND ENVIRONMENTAL TOBACCO SMOKE EARLY IN LIFE. SEVERAL CANDIDATE GENE STUDIES ON EPIGENETICS HAVE BEEN PUBLISHED TO DATE, BUT IT IS ONLY RECENTLY THAT GLOBAL METHYLATION ANALYSES HAVE BEEN PERFORMED FOR RESPIRATORY DISORDERS SUCH AS ASTHMA AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE. HOWEVER, LARGE-SCALE STUDIES WITH ADEQUATE POWER ARE YET TO BE PRESENTED IN CHILDREN, AND IMPLICATIONS FOR CLINICAL USE REMAIN TO BE EVALUATED. IN THIS REVIEW, WE SUMMARIZE THE RECENT ADVANCES IN EPIGENETICS AND RESPIRATORY DISORDERS IN CHILDREN, WITH A MAIN FOCUS ON METHODOLOGICAL CHALLENGES AND ANALYSES RELATED TO PHENOTYPE AND EXPOSURE USING GLOBAL METHYLATION APPROACHES. 2014 8 4460 37 MOLECULAR MECHANISMS OF ENVIRONMENTAL EXPOSURES AND HUMAN DISEASE. A SUBSTANTIAL PROPORTION OF DISEASE RISK FOR COMMON COMPLEX DISORDERS IS ATTRIBUTABLE TO ENVIRONMENTAL EXPOSURES AND POLLUTANTS. AN APPRECIATION OF HOW ENVIRONMENTAL POLLUTANTS ACT ON OUR CELLS TO PRODUCE DELETERIOUS HEALTH EFFECTS HAS LED TO ADVANCES IN OUR UNDERSTANDING OF THE MOLECULAR MECHANISMS UNDERLYING THE PATHOGENESIS OF CHRONIC DISEASES, INCLUDING CANCER AND CARDIOVASCULAR, NEURODEGENERATIVE AND RESPIRATORY DISEASES. HERE, WE DISCUSS EMERGING RESEARCH ON THE INTERPLAY OF ENVIRONMENTAL POLLUTANTS WITH THE HUMAN GENOME AND EPIGENOME. WE REVIEW EVIDENCE SHOWING THE ENVIRONMENTAL IMPACT ON GENE EXPRESSION THROUGH EPIGENETIC MODIFICATIONS, INCLUDING DNA METHYLATION, HISTONE MODIFICATION AND NON-CODING RNAS. WE ALSO HIGHLIGHT RECENT STUDIES THAT EVALUATE RECENTLY DISCOVERED MOLECULAR PROCESSES THROUGH WHICH THE ENVIRONMENT CAN EXERT ITS EFFECTS, INCLUDING EXTRACELLULAR VESICLES, THE EPITRANSCRIPTOME AND THE MITOCHONDRIAL GENOME. FINALLY, WE DISCUSS CURRENT CHALLENGES WHEN STUDYING THE EXPOSOME - THE CUMULATIVE MEASURE OF ENVIRONMENTAL INFLUENCES OVER THE LIFESPAN - AND ITS INTEGRATION INTO FUTURE ENVIRONMENTAL HEALTH RESEARCH. 2023 9 4840 41 ONCOGENOMIC DISRUPTIONS IN ARSENIC-INDUCED CARCINOGENESIS. CHRONIC EXPOSURE TO ARSENIC AFFECTS MORE THAN 200 MILLION PEOPLE WORLDWIDE, AND HAS BEEN ASSOCIATED WITH MANY ADVERSE HEALTH EFFECTS, INCLUDING CANCER IN SEVERAL ORGANS. THERE IS ACCUMULATING EVIDENCE THAT ARSENIC BIOTRANSFORMATION, A STEP IN THE ELIMINATION OF ARSENIC FROM THE HUMAN BODY, CAN INDUCE CHANGES AT A GENETIC AND EPIGENETIC LEVEL, LEADING TO CARCINOGENESIS. AT THE GENETIC LEVEL, ARSENIC INTERFERES WITH KEY CELLULAR PROCESSES SUCH AS DNA DAMAGE-REPAIR AND CHROMOSOMAL STRUCTURE, LEADING TO GENOMIC INSTABILITY. AT THE EPIGENETIC LEVEL, ARSENIC PLACES A HIGH DEMAND ON THE CELLULAR METHYL POOL, LEADING TO GLOBAL HYPOMETHYLATION AND HYPERMETHYLATION OF SPECIFIC GENE PROMOTERS. THESE ARSENIC-ASSOCIATED DNA ALTERATIONS RESULT IN THE DEREGULATION OF BOTH ONCOGENIC AND TUMOUR-SUPPRESSIVE GENES. FURTHERMORE, RECENT REPORTS HAVE IMPLICATED ABERRANT EXPRESSION OF NON-CODING RNAS AND THE CONSEQUENTIAL DISRUPTION OF SIGNALING PATHWAYS IN THE CONTEXT OF ARSENIC-INDUCED CARCINOGENESIS. THIS ARTICLE PROVIDES AN OVERVIEW OF THE ONCOGENOMIC ANOMALIES ASSOCIATED WITH ARSENIC EXPOSURE AND CONVEYS THE IMPORTANCE OF NON-CODING RNAS IN THE ARSENIC-INDUCED CARCINOGENIC PROCESS. 2017 10 6295 40 THE PROMISES AND CHALLENGES OF TOXICO-EPIGENOMICS: ENVIRONMENTAL CHEMICALS AND THEIR IMPACTS ON THE EPIGENOME. BACKGROUND: IT HAS BEEN ESTIMATED THAT A SUBSTANTIAL PORTION OF CHRONIC AND NONCOMMUNICABLE DISEASES CAN BE CAUSED OR EXACERBATED BY EXPOSURE TO ENVIRONMENTAL CHEMICALS. MULTIPLE LINES OF EVIDENCE INDICATE THAT EARLY LIFE EXPOSURE TO ENVIRONMENTAL CHEMICALS AT RELATIVELY LOW CONCENTRATIONS COULD HAVE LASTING EFFECTS ON INDIVIDUAL AND POPULATION HEALTH. ALTHOUGH THE POTENTIAL ADVERSE EFFECTS OF ENVIRONMENTAL CHEMICALS ARE KNOWN TO THE SCIENTIFIC COMMUNITY, REGULATORY AGENCIES, AND THE PUBLIC, LITTLE IS KNOWN ABOUT THE MECHANISTIC BASIS BY WHICH THESE CHEMICALS CAN INDUCE LONG-TERM OR TRANSGENERATIONAL EFFECTS. TO ADDRESS THIS QUESTION, EPIGENETIC MECHANISMS HAVE EMERGED AS THE POTENTIAL LINK BETWEEN GENETIC AND ENVIRONMENTAL FACTORS OF HEALTH AND DISEASE. OBJECTIVES: WE PRESENT AN OVERVIEW OF EPIGENETIC REGULATION AND A SUMMARY OF REPORTED EVIDENCE OF ENVIRONMENTAL TOXICANTS AS EPIGENETIC DISRUPTORS. WE ALSO DISCUSS THE ADVANTAGES AND CHALLENGES OF USING EPIGENETIC BIOMARKERS AS AN INDICATOR OF TOXICANT EXPOSURE, USING MEASURES THAT CAN BE TAKEN TO IMPROVE RISK ASSESSMENT, AND OUR PERSPECTIVES ON THE FUTURE ROLE OF EPIGENETICS IN TOXICOLOGY. DISCUSSION: UNTIL RECENTLY, EFFORTS TO APPLY EPIGENOMIC DATA IN TOXICOLOGY AND RISK ASSESSMENT WERE RESTRICTED BY AN INCOMPLETE UNDERSTANDING OF EPIGENOMIC VARIABILITY ACROSS TISSUE TYPES AND POPULATIONS. THIS IS POISED TO CHANGE WITH THE DEVELOPMENT OF NEW TOOLS AND CONCERTED EFFORTS BY RESEARCHERS ACROSS DISCIPLINES THAT HAVE LED TO A BETTER UNDERSTANDING OF EPIGENETIC MECHANISMS AND COMPREHENSIVE MAPS OF EPIGENOMIC VARIATION. WITH THE FOUNDATIONS NOW IN PLACE, WE FORESEE THAT UNPRECEDENTED ADVANCEMENTS WILL TAKE PLACE IN THE FIELD IN THE COMING YEARS. HTTPS://DOI.ORG/10.1289/EHP6104. 2020 11 3775 42 INTERACTIONS BETWEEN ARSENIC-INDUCED TOXICITY AND NUTRITION IN EARLY LIFE. EXPOSURE TO ARSENIC THROUGH DRINKING WATER IS A MAJOR PUBLIC HEALTH PROBLEM AFFECTING MOST COUNTRIES, ALTHOUGH THE SITUATION IS PARTICULARLY SEVERE IN LOW-INCOME NATIONS. THE HEALTH CONSEQUENCES OF CHRONIC ARSENIC EXPOSURE INCLUDE INCREASED RISK FOR VARIOUS FORMS OF CANCER AND NUMEROUS NONCANCER EFFECTS, INCLUDING DIABETES, SKIN DISEASES, CHRONIC COUGH, AND TOXIC EFFECTS ON LIVER, KIDNEY, CARDIOVASCULAR SYSTEM, AND PERIPHERAL AND CENTRAL NERVOUS SYSTEMS. IN RECENT YEARS INCREASING REPORTS OF EFFECTS ON FETAL AND CHILD DEVELOPMENT HAVE APPEARED. THERE SEEMS TO BE A WIDE VARIATION IN SUSCEPTIBILITY TO ARSENIC TOXICITY, WHICH IS LIKELY TO BE RELATED TO FACTORS SUCH AS VARIATION IN ARSENIC METABOLISM, NUTRITION, HOST-RELATED DEFENSE MECHANISMS, AND GENETIC PREDISPOSITION. THE MAIN MECHANISMS OF ARSENIC-NUTRITION INTERACTIONS INCLUDE ARSENIC-INDUCED OXIDATIVE STRESS, WHICH REQUIRES NUTRIENT-DEPENDENT DEFENSE SYSTEMS, AND ARSENIC METABOLISM (METHYLATION) VIA 1-CARBON METABOLISM, WHICH REQUIRES METHYL GROUPS, FOLIC ACID, VITAMIN B-12, AND BETAINE FOR THE REMETHYLATION OF HOMOCYSTEINE TO METHIONINE. AN EFFICIENT FIRST METHYLATION STEP IN COMBINATION WITH A SLOW SECOND METHYLATION STEP SEEMS TO BE MOST CRITICAL FROM A TOXICOLOGICAL POINT OF VIEW. A THIRD MODE OF ARSENIC-NUTRITION INTERACTION INVOLVES EPIGENETIC EFFECTS AND FETAL PROGRAMMING VIA DNA METHYLATION. 2007 12 2282 44 EPIGENETIC REGULATION IN EXPOSOME-INDUCED TUMORIGENESIS: EMERGING ROLES OF NCRNAS. ENVIRONMENTAL FACTORS, INCLUDING POLLUTANTS AND LIFESTYLE, CONSTITUTE A SIGNIFICANT ROLE IN SEVERE, CHRONIC PATHOLOGIES WITH AN ESSENTIAL SOCIETAL, ECONOMIC BURDEN. THE MEASUREMENT OF ALL ENVIRONMENTAL EXPOSURES AND ASSESSING THEIR CORRELATION WITH EFFECTS ON INDIVIDUAL HEALTH IS DEFINED AS THE EXPOSOME, WHICH INTERACTS WITH OUR UNIQUE CHARACTERISTICS SUCH AS GENETICS, PHYSIOLOGY, AND EPIGENETICS. EPIGENETICS INVESTIGATES MODIFICATIONS IN THE EXPRESSION OF GENES THAT DO NOT DEPEND ON THE UNDERLYING DNA SEQUENCE. SOME STUDIES HAVE CONFIRMED THAT ENVIRONMENTAL FACTORS MAY PROMOTE DISEASE IN INDIVIDUALS OR SUBSEQUENT PROGENY THROUGH EPIGENETIC ALTERATIONS. VARIATIONS IN THE EPIGENETIC MACHINERY CAUSE A SPECTRUM OF DIFFERENT DISORDERS SINCE THESE MECHANISMS ARE MORE SENSITIVE TO THE ENVIRONMENT THAN THE GENOME, DUE TO THE INHERENT REVERSIBLE NATURE OF THE EPIGENETIC LANDSCAPE. SEVERAL EPIGENETIC MECHANISMS, INCLUDING MODIFICATIONS IN DNA (E.G., METHYLATION), HISTONES, AND NONCODING RNAS CAN CHANGE GENOME EXPRESSION UNDER THE EXOGENOUS INFLUENCE. NOTABLY, THE ROLE OF LONG NONCODING RNAS IN EPIGENETIC PROCESSES HAS NOT BEEN WELL EXPLORED IN THE CONTEXT OF EXPOSOME-INDUCED TUMORIGENESIS. IN THE PRESENT REVIEW, OUR SCOPE IS TO PROVIDE RELEVANT EVIDENCE INDICATING THAT EPIGENETIC ALTERATIONS MEDIATE THOSE DETRIMENTAL EFFECTS CAUSED BY EXPOSURE TO ENVIRONMENTAL TOXICANTS, FOCUSING MAINLY ON A MULTI-STEP REGULATION BY DIVERSE NONCODING RNAS SUBTYPES. 2022 13 3404 38 HOW EPIGENETICS IMPACTS ON HUMAN DISEASES. EPIGENETICS IS A RAPIDLY GROWING FIELD OF BIOLOGY THAT STUDIES THE CHANGES IN GENE EXPRESSION THAT ARE NOT DUE TO ALTERATIONS IN THE DNA SEQUENCE BUT RATHER THE CHEMICAL MODIFICATIONS OF DNA AND ITS ASSOCIATED PROTEINS. EPIGENETIC MECHANISMS CAN PROFOUNDLY INFLUENCE GENE EXPRESSION, CELL DIFFERENTIATION, TISSUE DEVELOPMENT, AND DISEASE SUSCEPTIBILITY. UNDERSTANDING EPIGENETIC CHANGES IS ESSENTIAL TO ELUCIDATE THE MECHANISMS UNDERLYING THE INCREASINGLY RECOGNIZED ROLE OF ENVIRONMENTAL AND LIFESTYLE FACTORS IN HEALTH AND DISEASE AND THE INTERGENERATIONAL TRANSMISSION OF PHENOTYPES. RECENT STUDIES SUGGEST EPIGENETICS MAY BE CRITICAL IN VARIOUS DISEASES, FROM CARDIOVASCULAR DISEASE AND CANCER TO NEURODEVELOPMENTAL AND NEURODEGENERATIVE DISORDERS. EPIGENETIC MODIFICATIONS ARE POTENTIALLY REVERSIBLE AND COULD PROVIDE NEW THERAPEUTIC AVENUES FOR TREATING THESE DISEASES USING EPIGENETIC MODULATORS. MOREOVER, EPIGENETICS PROVIDE INSIGHT INTO DISEASE PATHOGENESIS AND BIOMARKERS FOR DISEASE DIAGNOSIS AND RISK STRATIFICATION. NEVERTHELESS, EPIGENETIC INTERVENTIONS HAVE THE POTENTIAL FOR UNINTENDED CONSEQUENCES AND MAY POTENTIALLY LEAD TO INCREASED RISKS OF UNEXPECTED OUTCOMES, SUCH AS ADVERSE DRUG REACTIONS, DEVELOPMENTAL ABNORMALITIES, AND CANCER. THEREFORE, RIGOROUS STUDIES ARE ESSENTIAL TO MINIMIZE THE RISKS ASSOCIATED WITH EPIGENETIC THERAPIES AND TO DEVELOP SAFE AND EFFECTIVE INTERVENTIONS FOR IMPROVING HUMAN HEALTH. THIS ARTICLE PROVIDES A SYNTHETIC AND HISTORICAL VIEW OF THE ORIGIN OF EPIGENETICS AND SOME OF THE MOST RELEVANT ACHIEVEMENTS. 2023 14 1928 48 ENVIRONMENTAL EXPOSURE MEASUREMENT IN CANCER EPIDEMIOLOGY. ENVIRONMENTAL EXPOSURES, USED IN THE BROADEST SENSE OF LIFESTYLE, INFECTIONS, RADIATION, NATURAL AND MAN-MADE CHEMICALS AND OCCUPATION, ARE A MAJOR CAUSE OF HUMAN CANCER. HOWEVER, THE PRECISE CONTRIBUTION OF SPECIFIC RISK FACTORS AND THEIR INTERACTION, BOTH WITH EACH OTHER AND WITH GENOTYPE, CONTINUES TO BE DIFFICULT TO ELUCIDATE. THIS IS PARTIALLY DUE TO LIMITATIONS IN ACCURATELY MEASURING EXPOSURE WITH THE SUBSEQUENT RISK OF MISCLASSIFICATION. ONE OF THE PRIMARY CHALLENGES OF MOLECULAR CANCER EPIDEMIOLOGY THEREFORE IS TO IMPROVE EXPOSURE ASSESSMENT. PROGRESS HAS BEEN MADE WITH BIOMARKERS SUCH AS CARCINOGENS AND THEIR METABOLITES, DNA AND PROTEIN ADDUCTS AND MUTATIONS MEASURED IN VARIOUS TISSUES AND BODY FLUIDS. NEVERTHELESS, MUCH REMAINS TO BE ACCOMPLISHED IN ORDER TO ESTABLISH AETIOLOGY AND PROVIDE THE EVIDENCE BASE FOR PUBLIC HEALTH DECISIONS. THIS REVIEW CONSIDERS SOME OF THE PRINCIPLES BEHIND THE APPLICATION OF EXPOSURE BIOMARKERS IN CANCER EPIDEMIOLOGY. IT ALSO DEMONSTRATES HOW THE SAME BIOMARKERS CAN CONTRIBUTE BOTH TO ESTABLISHING THE BIOLOGICAL PLAUSIBILITY OF ASSOCIATIONS BETWEEN EXPOSURE AND DISEASE AND BE VALUABLE ENDPOINTS IN INTERVENTION STUDIES. THE POTENTIAL OF NEW TECHNOLOGIES SUCH AS TRANSCRIPTOMICS, PROTEOMICS AND METABONOMICS TO PROVIDE A STEP CHANGE IN ENVIRONMENTAL EXPOSURE ASSESSMENT IS DISCUSSED. AN INCREASING RECOGNITION OF THE ROLE OF EPIGENETIC CHANGES IN CARCINOGENESIS PRESENTS A FRESH CHALLENGE AS ALTERATIONS IN DNA METHYLATION, HISTONE MODIFICATION AND MICRORNA IN RESPONSE TO ENVIRONMENTAL EXPOSURES DEMAND A NEW GENERATION OF EXPOSURE BIOMARKER. THE OVERALL IMPORTANCE OF THIS AREA OF RESEARCH IS BROUGHT INTO SHARP RELIEF BY THE LARGE PROSPECTIVE COHORT STUDIES (E.G. UK BIOBANK) WHICH NEED ACCURATE EXPOSURE MEASUREMENT IN ORDER TO SHED LIGHT ON THE COMPLEX GENE:ENVIRONMENT INTERACTIONS UNDERLYING COMMON CHRONIC DISORDERS INCLUDING CANCER. IT IS SUGGESTED THAT A CONCERTED EFFORT IS NOW REQUIRED, WITH APPROPRIATE FUNDING, TO DEVELOP AND VALIDATE THE REQUIRED EXPOSURE ASSESSMENT METHODOLOGY BEFORE THESE COHORTS COME TO MATURITY. 2009 15 738 32 CANCER SUSCEPTIBILITY: EPIGENETIC MANIFESTATION OF ENVIRONMENTAL EXPOSURES. CANCER IS A DISEASE THAT RESULTS FROM BOTH GENETIC AND EPIGENETIC CHANGES. DISCORDANT PHENOTYPES AND VARYING INCIDENCES OF COMPLEX DISEASES SUCH AS CANCER IN MONOZYGOTIC TWINS AS WELL AS GENETICALLY IDENTICAL LABORATORY ANIMALS HAVE LONG BEEN ATTRIBUTED TO DIFFERENCES IN ENVIRONMENTAL EXPOSURES. ACCUMULATING EVIDENCE INDICATES, HOWEVER, THAT DISPARITIES IN GENE EXPRESSION RESULTING FROM VARIABLE MODIFICATIONS IN DNA METHYLATION AND CHROMATIN STRUCTURE IN RESPONSE TO THE ENVIRONMENT ALSO PLAY A ROLE IN DIFFERENTIAL SUSCEPTIBILITY TO DISEASE. DESPITE A GROWING CONSENSUS ON THE IMPORTANCE OF EPIGENETICS IN THE ETIOLOGY OF CHRONIC HUMAN DISEASES, THE GENES MOST PRONE TO EPIGENETIC DYSREGULATION ARE INCOMPLETELY DEFINED. MOREOVER, NEITHER THE ENVIRONMENTAL AGENTS MOST STRONGLY AFFECTING THE EPIGENOME NOR THE CRITICAL WINDOWS OF VULNERABILITY TO ENVIRONMENTALLY INDUCED EPIGENETIC ALTERATIONS ARE ADEQUATELY CHARACTERIZED. THESE MAJOR DEFICITS IN KNOWLEDGE MARKEDLY IMPAIR OUR ABILITY TO UNDERSTAND FULLY THE ETIOLOGY OF CANCER AND THE IMPORTANCE OF THE EPIGENOME IN DIAGNOSING AND PREVENTING THIS DEVASTATING DISEASE. 2007 16 6287 39 THE POTENTIAL ROLE OF ENVIRONMENTAL FACTORS IN MODULATING MITOCHONDRIAL DNA EPIGENETIC MARKS. MANY STUDIES IMPLICATE MITOCHONDRIAL DYSFUNCTION IN THE DEVELOPMENT AND PROGRESSION OF NUMEROUS CHRONIC DISEASES. MITOCHONDRIA ARE RESPONSIBLE FOR MOST CELLULAR ENERGY PRODUCTION, AND UNLIKE OTHER CYTOPLASMIC ORGANELLES, MITOCHONDRIA CONTAIN THEIR OWN GENOME. MOST RESEARCH TO DATE, THROUGH INVESTIGATING MITOCHONDRIAL DNA COPY NUMBER, HAS FOCUSED ON LARGER STRUCTURAL CHANGES OR ALTERATIONS TO THE ENTIRE MITOCHONDRIAL GENOME AND THEIR ROLE IN HUMAN DISEASE. USING THESE METHODS, MITOCHONDRIAL DYSFUNCTION HAS BEEN LINKED TO CANCERS, CARDIOVASCULAR DISEASE, AND METABOLIC HEALTH. HOWEVER, LIKE THE NUCLEAR GENOME, THE MITOCHONDRIAL GENOME MAY EXPERIENCE EPIGENETIC ALTERATIONS, INCLUDING DNA METHYLATION THAT MAY PARTIALLY EXPLAIN SOME OF THE HEALTH EFFECTS OF VARIOUS EXPOSURES. RECENTLY, THERE HAS BEEN A MOVEMENT TO UNDERSTAND HUMAN HEALTH AND DISEASE WITHIN THE CONTEXT OF THE EXPOSOME, WHICH AIMS TO DESCRIBE AND QUANTIFY THE ENTIRETY OF ALL EXPOSURES PEOPLE ENCOUNTER THROUGHOUT THEIR LIVES. THESE INCLUDE, AMONG OTHERS, ENVIRONMENTAL POLLUTANTS, OCCUPATIONAL EXPOSURES, HEAVY METALS, AND LIFESTYLE AND BEHAVIORAL FACTORS. IN THIS CHAPTER, WE SUMMARIZE THE CURRENT RESEARCH ON MITOCHONDRIA AND HUMAN HEALTH, PROVIDE AN OVERVIEW OF THE CURRENT KNOWLEDGE ON MITOCHONDRIAL EPIGENETICS, AND DESCRIBE THE EXPERIMENTAL AND EPIDEMIOLOGIC STUDIES THAT HAVE INVESTIGATED PARTICULAR EXPOSURES AND THEIR RELATIONSHIPS WITH MITOCHONDRIAL EPIGENETIC MODIFICATIONS. WE CONCLUDE THE CHAPTER WITH SUGGESTIONS FOR FUTURE DIRECTIONS IN EPIDEMIOLOGIC AND EXPERIMENTAL RESEARCH THAT IS NEEDED TO ADVANCE THE GROWING FIELD OF MITOCHONDRIAL EPIGENETICS. 2023 17 4419 36 MOLECULAR AND EPIGENETIC MARKERS AS PROMISING TOOLS TO QUANTIFY THE EFFECT OF OCCUPATIONAL EXPOSURES AND THE RISK OF DEVELOPING NON-COMMUNICABLE DISEASES. NON-COMMUNICABLE DISEASES (NCDS) ARE CHRONIC DISEASES THAT ARE BY FAR THE LEADING CAUSE OF DEATH IN THE WORLD. MANY OCCUPATIONAL HAZARDS, TOGETHER WITH SOCIAL, ECONOMIC AND DEMOGRAPHIC FACTORS, HAVE BEEN ASSOCIATED TO NCDS DEVELOPMENT. GENETIC SUSCEPTIBILITY OR ENVIRONMENTAL EXPOSURES ALONE ARE NOT USUALLY SUFFICIENT TO EXPLAIN THE PATHOGENESIS OF NCDS, BUT CAN BE INTEGRATED IN A MORE COMPLEX SCENARIO THAT CAN RESULT IN PATHOLOGICAL PHENOTYPES. EPIGENETICS IS A CRUCIAL COMPONENT OF THIS SCENARIO, AS ITS CHANGES ARE RELATED TO SPECIFIC EXPOSURES, THEREFORE POTENTIALLY ABLE TO DISPLAY THE EFFECTS OF ENVIRONMENT ON THE GENOME, FILLING THE GAP BETWEEN GENETIC ASSET AND ENVIRONMENT IN EXPLAINING DISEASE DEVELOPMENT. TO DATE, THE MOST PROMISING BIOMARKERS HAVE BEEN ASSESSED IN OCCUPATIONAL COHORTS AS WELL AS IN CASE/CONTROL STUDIES AND INCLUDE DNA METHYLATION, HISTONE MODIFICATIONS, MICRORNA EXPRESSION, EXTRACELLULAR VESICLES, TELOMERE LENGTH, AND MITOCHONDRIAL ALTERATIONS. 2019 18 1932 34 ENVIRONMENTAL EXPOSURES: AN UNDERRECOGNIZED CONTRIBUTION TO NONCOMMUNICABLE DISEASES. PREVIOUS ATTEMPTS TO DETERMINE THE DEGREE TO WHICH EXPOSURE TO ENVIRONMENTAL FACTORS CONTRIBUTE TO NONCOMMUNICABLE DISEASES (NCDS) HAVE BEEN VERY CONSERVATIVE AND HAVE SIGNIFICANTLY UNDERESTIMATED THE ACTUAL CONTRIBUTION OF THE ENVIRONMENT FOR AT LEAST TWO REASONS. FIRSTLY, MOST PREVIOUS REPORTS HAVE EXCLUDED THE CONTRIBUTION OF LIFESTYLE BEHAVIORAL RISK FACTORS, BUT THESE USUALLY INVOLVE SIGNIFICANT EXPOSURE TO ENVIRONMENTAL CHEMICALS THAT INCREASE RISK OF DISEASE. SECONDLY, EARLY LIFE EXPOSURE TO CHEMICAL CONTAMINANTS IS NOW CLEARLY ASSOCIATED WITH AN ELEVATED RISK OF SEVERAL DISEASES LATER IN LIFE, BUT THESE CONNECTIONS ARE OFTEN DIFFICULT TO DISCERN. THIS IS ESPECIALLY TRUE FOR ASTHMA AND NEURODEVELOPMENTAL CONDITIONS, BUT THERE IS ALSO A MAJOR CONTRIBUTION TO THE DEVELOPMENT OF OBESITY AND CHRONIC DISEASES. MOST CANCERS ARE CAUSED BY ENVIRONMENTAL EXPOSURES IN GENETICALLY SUSCEPTIBLE INDIVIDUALS. IN ADDITION, NEW INFORMATION SHOWS SIGNIFICANT ASSOCIATIONS BETWEEN CARDIOVASCULAR DISEASES AND DIABETES AND EXPOSURE TO ENVIRONMENTAL CHEMICALS PRESENT IN AIR, FOOD, AND WATER. THESE RELATIONSHIPS LIKELY REFLECT THE COMBINATION OF EPIGENETIC EFFECTS AND GENE INDUCTION. ENVIRONMENTAL FACTORS CONTRIBUTE SIGNIFICANTLY MORE TO NCDS THAN PREVIOUS REPORTS HAVE SUGGESTED. PREVENTION NEEDS TO SHIFT FOCUS FROM INDIVIDUAL RESPONSIBILITY TO SOCIETAL RESPONSIBILITY AND AN UNDERSTANDING THAT EFFECTIVE PREVENTION OF NCDS ULTIMATELY RELIES ON IMPROVED ENVIRONMENTAL MANAGEMENT TO REDUCE EXPOSURE TO MODIFIABLE RISKS. 2013 19 1938 40 EPIDEMIOLOGIC EVIDENCE FOR ASSOCIATION BETWEEN ADVERSE ENVIRONMENTAL EXPOSURES IN EARLY LIFE AND EPIGENETIC VARIATION: A POTENTIAL LINK TO DISEASE SUSCEPTIBILITY? A GROWING BODY OF EVIDENCE SUGGESTS THAT THE RISK OF DEVELOPMENT AND PROGRESSION OF A VARIETY OF HUMAN CHRONIC DISEASES DEPENDS ON EPIGENETIC MODIFICATIONS TRIGGERED BY ENVIRONMENTAL CUES DURING EARLY LIFE SENSITIVE STAGES. EXPOSURES TO ENVIRONMENTAL FACTORS SUCH AS ADVERSE NUTRITIONAL, PSYCHOLOGICAL, AND SOCIAL CONDITIONS, AS WELL AS POLLUTANTS AND SUBSTANCE ABUSE IN EARLY LIFE, HAVE BEEN SHOWN TO BE IMPORTANT DETERMINANTS OF EPIGENETIC PROGRAMMING OF CHRONIC PATHOLOGICAL CONDITIONS IN HUMAN POPULATIONS. OVER THE PAST YEARS, IT HAS BECOME INCREASINGLY CLEAR DUE TO THE EPIGENOME-WIDE ASSOCIATION STUDIES (EWASS) THAT EARLY LIFE ADVERSE ENVIRONMENTAL EVENTS MAY TRIGGER WIDESPREAD AND PERSISTENT ALTERATIONS IN TRANSCRIPTIONAL PROFILING. SEVERAL CANDIDATE GENES HAVE BEEN IDENTIFIED UNDERLYING THESE ASSOCIATIONS. IN THIS CONTEXT, DNA METHYLATION IS THE MOST INTENSIVELY STUDIED EPIGENETIC PHENOMENON. IN THIS REVIEW, THE CLINICAL AND EPIDEMIOLOGICAL EVIDENCE FOR THE ROLE OF EPIGENETIC FACTORS IN MEDIATING THE LINK BETWEEN EARLY LIFE EXPERIENCES AND LONG-TERM HEALTH OUTCOMES ARE SUMMARIZED. 2015 20 2651 40 EPIGENOMICS AND TRANSCRIPTOMICS IN THE PREDICTION AND DIAGNOSIS OF CHILDHOOD ASTHMA: ARE WE THERE YET? ASTHMA IS THE MOST COMMON NON-COMMUNICABLE CHRONIC DISEASE OF CHILDHOOD. DESPITE ITS HIGH PREVALENCE, TO DATE WE LACK METHODS THAT ARE BOTH EFFICIENT AND ACCURATE IN DIAGNOSING ASTHMA. MOST TRADITIONAL APPROACHES HAVE BEEN BASED ON GARNERING CLINICAL EVIDENCE, SUCH AS RISK FACTORS AND EXPOSURES. GIVEN THE HIGH HERITABILITY OF ASTHMA, MORE RECENT APPROACHES HAVE LOOKED AT GENETIC POLYMORPHISMS AS POTENTIAL "RISK FACTORS." HOWEVER, GENETIC VARIANTS EXPLAIN ONLY A SMALL PROPORTION OF ASTHMA RISK, AND HAVE BEEN LESS THAN OPTIMAL AT PREDICTING RISK FOR INDIVIDUAL SUBJECTS. EPIGENOMIC STUDIES OFFER SIGNIFICANT ADVANTAGES OVER PREVIOUS APPROACHES. EPIGENETIC REGULATION IS HIGHLY TISSUE-SPECIFIC, AND CAN INDUCE BOTH SHORT- AND LONG-TERM CHANGES IN GENE EXPRESSION. SUCH CHANGES CAN START IN UTERO, CAN VARY THROUGHOUT THE LIFE SPAN, AND IN SOME INSTANCES CAN BE PASSED ON FROM ONE GENERATION TO ANOTHER. MOST IMPORTANTLY, THE EPIGENOME CAN BE MODIFIED BY ENVIRONMENTAL FACTORS AND EXPOSURES, AND THUS EPIGENETIC AND TRANSCRIPTOMIC PROFILING MAY YIELD THE MOST ACCURATE RISK ESTIMATES FOR A GIVEN PATIENT BY INCORPORATING ENVIRONMENTAL (AND TREATMENT) EFFECTS THROUGHOUT THE LIFESPAN. HERE WE WILL REVIEW THE MOST RECENT ADVANCES IN THE USE OF EPIGENETIC AND TRANSCRIPTOMIC ANALYSIS FOR THE EARLY DIAGNOSIS OF ASTHMA AND ATOPY, AS WELL AS CHALLENGES AND FUTURE DIRECTIONS IN THE FIELD AS IT MOVES FORWARD. WE WILL PARTICULARLY FOCUS ON DNA METHYLATION, THE MOST STUDIED MECHANISM OF EPIGENETIC REGULATION. 2019