1 6620 104 UNDERSTANDING DEVELOPMENT AND PREVENTION OF CHRONIC PHYSICAL AGGRESSION: TOWARDS EXPERIMENTAL EPIGENETIC STUDIES. THE AIM OF THIS PAPER WAS TO HIGHLIGHT HOW DEVELOPMENTAL PSYCHOPATHOLOGY, EPIGENETICS AND PREVENTION EXPERIMENTS ARE STARTING TO BLEND TOGETHER TO EXPLAIN THE DEVELOPMENTAL CAUSES OF CHRONIC PHYSICAL AGGRESSION (CPA) AND, MORE IMPORTANTLY, TO HELP PREVENT CPA AND ITS ASSOCIATED PHYSICAL, MENTAL AND SOCIAL PROBLEMS. AFTER DEFINING THE KEYWORDS (PREVENTION, CHRONIC AND PHYSICAL AGGRESSION), A SELECTED REVIEW OF PUBLISHED STUDIES IS USED TO ANSWER THE FOLLOWING FOUR QUESTIONS: WHEN SHOULD WE ATTEMPT TO PREVENT ONSET OF CPA? WHAT ARE THE RISK FACTORS FOR CPA? HAVE EARLY CHILDHOOD INTERVENTIONS BEEN SHOWN TO PREVENT CPA? CAN EARLY PREVENTIVE INTERVENTIONS BENEFIT FROM EPIGENETIC STUDIES? THE LAST SECTION OF THIS PAPER GIVES TWO EXAMPLES OF EXPERIMENTAL PREVENTION DESIGNS THAT INTEGRATE PRESENT KNOWLEDGE OF CPA DEVELOPMENT, RISK FACTORS, EARLY CHILDHOOD PREVENTIVE INTERVENTIONS AND EPIGENETIC PROGRAMMING OF BRAIN DEVELOPMENT DURING PREGNANCY AND EARLY CHILDHOOD. I CONCLUDE THAT RANDOMIZED CONTROL TRIALS OF PREVENTIVE INTERVENTIONS DURING PREGNANCY AND EARLY CHILDHOOD WITH A SPECIFIC FOCUS ON EPIGENETIC EFFECTS ARE THE RESEARCH DESIGN MOST LIKELY TO ADVANCE OUR UNDERSTANDING OF THE BIOPSYCHOSOCIAL MECHANISMS THAT LEAD TO CPA, AND THE ONLY RESEARCH DESIGN THAT CAN IDENTIFY EFFECTIVE INTERVENTIONS FOR PREVENTING THE DEVELOPMENT OF CPA. 2008 2 5650 35 SEX DIFFERENCES IN THE DEVELOPMENT OF PHYSICAL AGGRESSION: AN INTERGENERATIONAL PERSPECTIVE AND IMPLICATIONS FOR PREVENTIVE INTERVENTIONS. THIS ARTICLE REVIEWS THE STATE OF KNOWLEDGE ON THE DEVELOPMENT OF CHRONIC PHYSICAL AGGRESSION (CPA), WITH THE AIM OF IDENTIFYING THE MOST EFFECTIVE PREVENTION STRATEGIES. WE SPECIFICALLY FOCUS ON THE EARLY DEVELOPMENT OF PHYSICAL AGGRESSION, ON SEX DIFFERENCES IN THE USE OF PHYSICAL AGGRESSION, AND ON THE TRANSMISSION OF BEHAVIOR PROBLEMS FROM ONE GENERATION TO THE OTHER. THE BODY OF RESEARCH ON THE DEVELOPMENT OF CPA FROM THE PAST THREE DECADES THAT WE REVIEW SHOWS INCREASING EVIDENCE THAT ITS PREVENTION REQUIRES A LONG-TERM BIOPSYCHOSOCIAL DEVELOPMENTAL APPROACH WHICH ALSO MUST INCLUDE AN INTERGENERATIONAL PERSPECTIVE. RECENT GENETIC AND EPIGENETIC RESEARCH HAS INDICATED THAT THERE ARE BOTH IMPORTANT GENETIC AND ENVIRONMENTAL EFFECTS ON GENE EXPRESSION WHICH START AT CONCEPTION. WE CONCLUDE THAT ONE OF THE MOST EFFECTIVE STRATEGIES TO BREAK THE INTERGENERATIONAL TRANSMISSION OF CPA INVOLVES GIVING LONG-TERM SUPPORT TO PREGNANT WOMEN WITH A HISTORY OF BEHAVIOR PROBLEMS, THEIR SPOUSE, AND THEIR OFFSPRING. 2019 3 1248 32 CURRENT EVIDENCE FOR BIOLOGICAL BIOMARKERS AND MECHANISMS UNDERLYING ACUTE TO CHRONIC PAIN TRANSITION ACROSS THE PEDIATRIC AGE SPECTRUM. CHRONIC PAIN IS HIGHLY PREVALENT IN THE PEDIATRIC POPULATION. MANY FACTORS ARE INVOLVED IN THE TRANSITION FROM ACUTE TO CHRONIC PAIN. CURRENTLY, THERE ARE CONCEPTUAL MODELS PROPOSED, BUT THEY LACK A MECHANISTICALLY SOUND INTEGRATED THEORY CONSIDERING THE STAGES OF CHILD DEVELOPMENT. OBJECTIVE BIOMARKERS ARE CRITICALLY NEEDED FOR THE DIAGNOSIS, RISK STRATIFICATION, AND PROGNOSIS OF THE PATHOLOGICAL STAGES OF PAIN CHRONIFICATION. IN THIS ARTICLE, WE SUMMARIZE THE CURRENT EVIDENCE ON MECHANISMS AND BIOMARKERS OF ACUTE TO CHRONIC PAIN TRANSITIONS IN INFANTS AND CHILDREN THROUGH THE DEVELOPMENTAL LENS. THE GOAL IS TO IDENTIFY GAPS AND OUTLINE FUTURE DIRECTIONS FOR BASIC AND CLINICAL RESEARCH TOWARD A DEVELOPMENTALLY INFORMED THEORY OF PAIN CHRONIFICATION IN THE PEDIATRIC POPULATION. AT THE OUTSET, THE IMPORTANCE OF OBJECTIVE BIOMARKERS FOR CHRONIFICATION OF PAIN IN CHILDREN IS OUTLINED, FOLLOWED BY A SUMMARY OF THE CURRENT EVIDENCE ON THE MECHANISMS OF ACUTE TO CHRONIC PAIN TRANSITION IN ADULTS, IN ORDER TO CONTRAST WITH THE DEVELOPMENTAL MECHANISMS OF PAIN CHRONIFICATION IN THE PEDIATRIC POPULATION. EVIDENCE IS PRESENTED TO SHOW THAT CHRONIC PAIN MAY HAVE ITS ORIGIN FROM INSULTS EARLY IN LIFE, WHICH PRIME THE CHILD FOR THE DEVELOPMENT OF CHRONIC PAIN IN LATER LIFE. FURTHERMORE, AVAILABLE GENETIC, EPIGENETIC, PSYCHOPHYSICAL, ELECTROPHYSIOLOGICAL, NEUROIMAGING, NEUROIMMUNE, AND SEX MECHANISMS ARE DESCRIBED IN INFANTS AND OLDER CHILDREN. IN CONCLUSION, FUTURE DIRECTIONS ARE DISCUSSED WITH A FOCUS ON RESEARCH GAPS, TRANSLATIONAL AND CLINICAL IMPLICATIONS. UTILIZATION OF DEVELOPMENTAL MECHANISMS FRAMEWORK TO INFORM CLINICAL DECISION-MAKING AND STRATEGIES FOR PREVENTION AND MANAGEMENT OF ACUTE TO CHRONIC PAIN TRANSITIONS IN CHILDREN, IS HIGHLIGHTED. 2023 4 1765 28 EARLY-LIFE ADVERSITY-INDUCED LONG-TERM EPIGENETIC PROGRAMMING ASSOCIATED WITH EARLY ONSET OF CHRONIC PHYSICAL AGGRESSION: STUDIES IN HUMANS AND ANIMALS. OBJECTIVES: TO EXAMINE WHETHER CHRONIC PHYSICAL AGGRESSION (CPA) IN ADULTHOOD CAN BE EPIGENETICALLY PROGRAMMED EARLY IN LIFE DUE TO EXPOSURE TO EARLY-LIFE ADVERSITY. METHODS: LITERATURE SEARCH OF PUBLIC DATABASES SUCH AS PUBMED/MEDLINE AND SCOPUS. RESULTS: CHILDREN/ADOLESCENTS SUSCEPTIBLE FOR CPA AND EXPOSED TO EARLY-LIFE ABUSE FAIL TO EFFICIENTLY COPE WITH STRESS THAT IN TURN RESULTS IN THE DEVELOPMENT OF CPA LATER IN LIFE. THIS PHENOMENON WAS OBSERVED IN HUMANS AND ANIMAL MODELS OF AGGRESSION. THE SUSCEPTIBILITY TO AGGRESSION IS A COMPLEX TRAIT THAT IS REGULATED BY THE INTERACTION BETWEEN ENVIRONMENTAL AND GENETIC FACTORS. EPIGENETIC MECHANISMS MEDIATE THIS INTERACTION. SUBJECTS EXPOSED TO STRESS EARLY IN LIFE EXHIBITED LONG-TERM EPIGENETIC PROGRAMMING THAT CAN INFLUENCE THEIR BEHAVIOUR IN ADULTHOOD. THIS PROGRAMMING AFFECTS EXPRESSION OF MANY GENES NOT ONLY IN THE BRAIN BUT ALSO IN OTHER SYSTEMS SUCH AS NEUROENDOCRINE AND IMMUNE. CONCLUSIONS: THE PROPENSITY TO ADULT CPA BEHAVIOUR IN SUBJECTS EXPERIENCED TO EARLY-LIFE ADVERSITY IS MEDIATED BY EPIGENETIC PROGRAMMING THAT INVOLVES LONG-TERM SYSTEMIC EPIGENETIC ALTERATIONS IN A WHOLE GENOME. 2019 5 4591 32 NARRATIVE REVIEW OF THE COMPLEX INTERACTION BETWEEN PAIN AND TRAUMA IN CHILDREN: A FOCUS ON BIOLOGICAL MEMORY, PRECLINICAL DATA, AND EPIGENETIC PROCESSES. THE INCIDENCE AND COLLECTIVE IMPACT OF EARLY ADVERSE EXPERIENCES, TRAUMA, AND PAIN CONTINUE TO INCREASE. THIS UNDERSCORES THE URGENT NEED FOR TRANSLATIONAL EFFORTS BETWEEN CLINICAL AND PRECLINICAL RESEARCH TO BETTER UNDERSTAND THE UNDERLYING MECHANISMS AND DEVELOP EFFECTIVE THERAPEUTIC APPROACHES. AS OUR UNDERSTANDING OF THESE ISSUES IMPROVES FROM STUDIES IN CHILDREN AND ADOLESCENTS, WE CAN CREATE MORE PRECISE PRECLINICAL MODELS AND ULTIMATELY TRANSLATE OUR FINDINGS BACK TO CLINICAL PRACTICE. A MULTIDISCIPLINARY APPROACH IS ESSENTIAL FOR ADDRESSING THE COMPLEX AND WIDE-RANGING EFFECTS OF THESE EXPERIENCES ON INDIVIDUALS AND SOCIETY. THIS NARRATIVE REVIEW AIMS TO (1) DEFINE PAIN AND TRAUMA EXPERIENCES IN CHILDHOOD AND ADOLESCENTS, (2) DISCUSS THE RELATIONSHIP BETWEEN PAIN AND TRAUMA, (3) CONSIDER THE ROLE OF BIOLOGICAL MEMORY, (4) DECIPHER THE RELATIONSHIP BETWEEN PAIN AND TRAUMA USING PRECLINICAL DATA, AND (5) EXAMINE THE ROLE OF THE ENVIRONMENT BY INTRODUCING THE IMPORTANCE OF EPIGENETIC PROCESSES. THE ULTIMATE SCOPE IS TO BETTER UNDERSTAND THE WIDE-RANGING EFFECTS OF TRAUMA, ABUSE, AND CHRONIC PAIN ON CHILDREN AND ADOLESCENTS, HOW THEY OCCUR, AND HOW TO PREVENT OR MITIGATE THEIR EFFECTS AND DEVELOP EFFECTIVE TREATMENT STRATEGIES THAT ADDRESS BOTH THE UNDERLYING CAUSES AND THE ASSOCIATED PHYSIOLOGICAL AND PSYCHOLOGICAL EFFECTS. 2023 6 6823 25 [GENERAL CONCEPTS OF EPIGENETICS: PROJECTIONS IN PAEDIATRICS]. CURRENT EVIDENCE SUPPORTS THE NOTION THAT ALTERATIONS IN INTRAUTERINE GROWTH AND DURING THE FIRST YEARS OF LIFE HAVE A SUBSTANTIAL EFFECT ON THE RISK FOR THE DEVELOPMENT OF CHRONIC DISEASE, WHICH IN SOME CASES IS EVEN HIGHER THAN THOSE DUE TO GENETIC FACTORS. THE PERSISTENCE AND REPRODUCIBILITY OF THE PHENOTYPES ASSOCIATED WITH ALTERED EARLY DEVELOPMENT SUGGEST THE PARTICIPATION OF MECHANISMS THAT WOULD RECORD ENVIRONMENTAL CUES, GENERATING A CELLULAR REPROGRAMMING (I.E., EPIGENETIC MECHANISMS). THIS REVIEW IS AN INTRODUCTION TO A SERIES OF FIVE ARTICLES FOCUSED ON THE PARTICIPATION OF EPIGENETIC MECHANISMS IN THE DEVELOPMENT OF HIGHLY PREVALENT CHRONIC DISEASES (I.E., CARDIOVASCULAR, METABOLIC, ASTHMA/ALLERGIES AND CANCER) AND THEIR ORIGINS IN THE FOETAL AND NEONATAL PERIOD. THIS SERIES OF ARTICLES AIMS TO SHOW THE STATE OF THE ART IN THIS RESEARCH AREA AND PRESENT THE UPCOMING CLUES AND CHALLENGES, IN WHICH PAEDIATRICIANS HAVE A PROMINENT ROLE, DEVELOPING STRATEGIES FOR THE PREVENTION, EARLY DETECTION AND FOLLOW-UP. 2016 7 6892 19 [SIGNIFICANCE OF PREVENTING DEVELOPMENTAL ORIGINS OF DISEASES IN IMPROVING POPULATION QUALITY]. MORE STUDIES SHOW THAT VARIOUS DISEASES, ESPECIALLY CHRONIC NON-INFECTIOUS DISEASES, HAVE DEVELOPMENTAL ORIGIN. DEVELOPMENTAL ORIGINS OF DISEASES ARE MAINLY DUE TO GAMETES AND EARLY LIFE DEVELOPMENT STAGE BEING EXPOSED TO ADVERSE ENVIRONMENT, RESULTING IN ABNORMAL MODIFICATION OF EPIGENETIC AND STABLE INHERITANCE TO THE ADULT STAGE, WHICH COULD MAKE THE RISK OF VARIOUS LONG-TERM DISEASES OF INDIVIDUALS HIGH. THE THEORY OF DEVELOPMENTAL ORIGIN PROVIDES A NEW PERSPECTIVE FOR THE OCCURRENCE AND DEVELOPMENT OF DISEASES, AND ALSO PROVIDES A THEORETICAL BASIS FOR DISEASE PREVENTION. ATTACHING IMPORTANCE TO MATERNAL AND CHILD HEALTH CARE AND LIFE-CYCLE MANAGEMENT IS CONDUCIVE TO THE PREVENTION OF DEVELOPMENTAL DISEASES AND IS OF GREAT SIGNIFICANCE TO THE IMPROVEMENT OF POPULATION QUALITY. 2023 8 6065 33 THE DEVELOPMENTAL ORIGINS OF CHRONIC PHYSICAL AGGRESSION: BIOLOGICAL PATHWAYS TRIGGERED BY EARLY LIFE ADVERSITY. LONGITUDINAL EPIDEMIOLOGICAL STUDIES WITH BIRTH COHORTS HAVE SHOWN THAT PHYSICAL AGGRESSION IN HUMANS DOES NOT APPEAR SUDDENLY IN ADOLESCENCE AS COMMONLY THOUGHT. IN FACT, PHYSICALLY AGGRESSIVE BEHAVIOUR IS OBSERVED AS EARLY AS 12 MONTHS AFTER BIRTH, ITS FREQUENCY PEAKS AROUND 2-4 YEARS OF AGE AND DECREASES IN FREQUENCY UNTIL EARLY ADULTHOOD. HOWEVER, A MINORITY OF CHILDREN (3-7%) MAINTAIN A HIGH FREQUENCY OF PHYSICAL AGGRESSION FROM CHILDHOOD TO ADOLESCENCE AND DEVELOP SERIOUS SOCIAL ADJUSTMENT PROBLEMS DURING ADULTHOOD. GENETIC FACTORS AND EARLY SOCIAL EXPERIENCES, AS WELL AS THEIR INTERACTION, HAVE BEEN SHOWN TO PLAY AN IMPORTANT ROLE IN THE DEVELOPMENT OF CHRONIC AGGRESSIVE BEHAVIOUR. HOWEVER, THE BIOLOGICAL MECHANISMS UNDERLYING THESE ASSOCIATIONS ARE JUST BEGINNING TO BE UNCOVERED. RECENT EVIDENCE SUGGESTS THAT EPIGENETIC MECHANISMS ARE RESPONSIVE TO ADVERSE ENVIRONMENTS AND COULD BE INVOLVED IN THE DEVELOPMENT OF CHRONIC AGGRESSION. USING BOTH GENE CANDIDATE AND GENOMIC APPROACHES, RECENT STUDIES HAVE IDENTIFIED EPIGENETIC MARKS, SUCH AS DNA METHYLATION ALTERATIONS IN GENES INVOLVED IN THE STRESS RESPONSE AND THE SEROTONIN AND IMMUNE SYSTEMS TO BE PARTLY RESPONSIBLE FOR THE LONG-LASTING EFFECTS OF EARLY ADVERSITY. FURTHER LONGITUDINAL STUDIES WITH BIOLOGICAL, ENVIRONMENTAL AND BEHAVIOURAL ASSESSMENTS FROM BIRTH ONWARDS ARE NEEDED TO ELUCIDATE THE SEQUENCE OF EVENTS THAT LEADS TO THESE LONG-LASTING EPIGENETIC MARKS ASSOCIATED WITH EARLY ADVERSITY AND AGGRESSION. 2015 9 6822 29 [GENDER MEDICINE. SEX- AND GENDER-SPECIFIC ASPECTS OF CLINICAL MEDICINE]. GENDER MEDICINE STUDIES SEX- AND GENDER-BASED DIFFERENCES IN THE DEVELOPMENT AND PREVENTION OF DISEASES, THE AWARENESS AND PRESENTATION OF SYMPTOMS, AND THE EFFECTIVENESS OF THERAPY. GENDER MEDICINE IS PART OF PERSONALIZED MEDICINE, CONSIDERING DIFFERENCES IN BIOLOGICAL AND PSYCHOSOCIAL FACTORS INDIVIDUALLY. THERE ARE DIFFERENCES IN GENES, CHROMOSOMES, HORMONES, AND METABOLISM AS WELL AS DIFFERENCES IN CULTURE, ENVIRONMENT, AND SOCIETY. LIFELONG INTERACTIONS BETWEEN PHYSICAL AND PSYCHOSOCIAL FACTORS WILL INFLUENCE THE HEALTH AND ILL-HEALTH OF MEN AND WOMEN IN DIFFERENT WAYS. EPIGENETIC MODIFICATIONS PROVIDE EVIDENCE OF THE IMPACT OF ENVIRONMENT AND LIFESTYLE DURING VULNERABLE PHASES ON BIOLOGICAL PROCESSES, EFFECTING FUTURE GENERATIONS. MATERNAL LIFESTYLE AND ENVIRONMENTAL FACTORS DURING PREGNANCY CAN IMPACT THE HEALTH OF OFFSPRING IN LATER LIFE ALREADY IN UTERO IN A SEX-SPECIFIC WAY. PAIN, STRESS, AND COPING STYLES DIFFER BETWEEN MEN AND WOMEN. WOMEN EXPERIENCE MORE DRAMATIC PHYSICAL CHANGES DURING THEIR LIFETIME, WHICH ARE ASSOCIATED WITH SPECIFIC BURDENS AND PSYCHOSOCIAL ALTERATIONS. WOMEN WITH MULTIPLE ROLES AND RESPONSIBILITIES SUFFERING FROM STRESS DEVELOP DEPRESSION MORE FREQUENTLY. HOWEVER, MEN ARE OFTEN NOT DIAGNOSED AND TREATED APPROPRIATELY IN CASES OF DEPRESSION OR OSTEOPOROSIS, DISEASES THAT ARE TYPICALLY CONSIDERED "FEMALE." THERE ARE PROMINENT DIFFERENCES BETWEEN MEN AND WOMEN IN MEDICINE REGARDING THE IMMUNE SYSTEM, INFLAMMATION, AND NONCOMMUNICABLE DISEASES SUCH AS OBESITY, TYPE 2 DIABETES, HYPERTENSION, AND CARDIOVASCULAR DISEASE. WOMEN EXPERIENCE MORE OFTEN AUTOIMMUNE DISEASES AND SUFFER MORE FREQUENTLY FROM (CHRONIC) PAIN, NEURODEGENERATIVE CHANGES, AND FUNCTIONAL DISABILITIES. MEN HAVE SHORTER LIFE EXPECTANCY BUT RELATIVELY MORE HEALTHY YEARS OF LIFE, WHICH IS IN GREATER PART ASCRIBED TO PSYCHOSOCIAL DETERMINANTS. STATE-OF-THE-ART CLINICAL MEDICINE COMPRISES INDIVIDUAL RISK FACTORS BASED ON SEX- AND GENDER-SENSITIVE HEALTH PROGRAMS IN ORDER TO IMPROVE THE HEALTH-RELATED QUALITY OF LIFE FOR MEN AND WOMEN. 2014 10 2651 32 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 11 1932 33 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 12 3582 19 IMPACT OF PRENATAL AND EARLY LIFE ENVIRONMENTAL EXPOSURES ON NORMAL HUMAN DEVELOPMENT. THE GLOBAL BURDEN AND PATTERN OF DISEASE HAS CHANGED IN RECENT DECADES, WITH FEWER EARLY CHILDHOOD DEATHS AND LONGER LIVES COMPLICATED BY CHRONIC DISEASE. DISRUPTION OF NORMAL HUMAN GROWTH AND DEVELOPMENT BY ADVERSE ENVIRONMENTAL EXPOSURES, ESPECIALLY DURING FOETAL DEVELOPMENT AND EARLY POSTNATAL LIFE INCREASE LIFE-LONG RISK OF CHRONIC DISEASE. THE DEVELOPMENTAL TIMING AND METHOD OF ADVERSE EXPOSURE DETERMINES THE LIKELY IMPACT ON HEALTH AND DEVELOPMENT. WHILE MANY ORGAN SYSTEMS ARE STRUCTURALLY AND FUNCTIONALLY MATURE AT BIRTH, THE CNS, RESPIRATORY AND IMMUNE SYSTEMS ARE NOT AND UNDERGO PROLONGED PERIODS OF POSTNATAL GROWTH AND DEVELOPMENT. AS SUCH, THESE ORGAN SYSTEMS ARE VULNERABLE TO ADVERSE EFFECTS OF BOTH PRENATAL AND POSTNATAL ENVIRONMENTAL EXPOSURES. WHILE THE PRECISE MECHANISMS UNDERLYING CHRONIC DISEASE ARE UNKNOWN, EPIGENETIC MECHANISMS AND THE INDUCTION OF OXIDATIVE STRESS ARE LIKELY TO BE INVOLVED. AN UNDERSTANDING OF THESE PROCESSES IS NECESSARY TO DEVELOP MITIGATION STRATEGIES AIMED AT REDUCING CHRONIC DISEASE PREVALENCE. 2021 13 1736 33 EARLY DETECTION AND PREVENTION OF SCHIZOPHRENIC PSYCHOSIS-A REVIEW. PSYCHOTIC DISORDERS OFTEN RUN A CHRONIC COURSE AND ARE ASSOCIATED WITH A CONSIDERABLE EMOTIONAL AND SOCIAL IMPACT FOR PATIENTS AND THEIR RELATIVES. THEREFORE, EARLY RECOGNITION, COMBINED WITH THE POSSIBILITY OF PREVENTIVE INTERVENTION, IS URGENTLY WARRANTED SINCE THE DURATION OF UNTREATED PSYCHOSIS (DUP) SIGNIFICANTLY DETERMINES THE FURTHER COURSE OF THE DISEASE. IN ADDITION TO ESTABLISHED DIAGNOSTIC TOOLS, NEUROBIOLOGICAL FACTORS IN THE DEVELOPMENT OF SCHIZOPHRENIC PSYCHOSES ARE INCREASINGLY BEING INVESTIGATED. IT IS SHOWN THAT NUMEROUS MOLECULAR ALTERATIONS ALREADY EXIST BEFORE THE CLINICAL ONSET OF THE DISEASE. AS SCHIZOPHRENIC PSYCHOSES ARE NOT ELICITED BY A SINGLE MUTATION IN THE DEOXYRIBONUCLEIC ACID (DNA) SEQUENCE, EPIGENETICS LIKELY CONSTITUTE THE MISSING LINK BETWEEN ENVIRONMENTAL INFLUENCES AND DISEASE DEVELOPMENT AND COULD POTENTIALLY SERVE AS A BIOMARKER. THE RESULTS FROM TRANSCRIPTOMIC AND PROTEOMIC STUDIES POINT TO A DYSREGULATED IMMUNE SYSTEM, LIKELY EVOKED BY EPIGENETIC ALTERATIONS. DESPITE THE INCREASING KNOWLEDGE OF THE NEUROBIOLOGICAL MECHANISMS INVOLVED IN THE DEVELOPMENT OF PSYCHOTIC DISORDERS, FURTHER RESEARCH EFFORTS WITH LARGE POPULATION-BASED STUDY DESIGNS ARE NEEDED TO IDENTIFY SUITABLE BIOMARKERS. IN CONCLUSION, A COMBINATION OF BLOOD EXAMINATIONS, FUNCTIONAL IMAGING TECHNIQUES, ELECTROENCEPHALOGRAPHY (EEG) INVESTIGATIONS AND POLYGENIC RISK SCORES SHOULD BE CONSIDERED AS THE BASIS FOR PREDICTING HOW SUBJECTS WILL TRANSITION INTO MANIFEST PSYCHOSIS. 2021 14 6064 29 THE DEVELOPMENTAL ORIGINS OF ADULT DISEASE. EPIDEMIOLOGICAL AND CLINICAL OBSERVATIONS HAVE LED TO THE HYPOTHESIS THAT THE RISK OF DEVELOPING SOME CHRONIC DISEASES IN ADULTHOOD IS INFLUENCED NOT ONLY BY GENETIC AND ADULT LIFESTYLE FACTORS, BUT ALSO BY ENVIRONMENTAL FACTORS ACTING IN EARLY LIFE. THESE FACTORS ACT THROUGH THE PROCESSES OF DEVELOPMENTAL PLASTICITY AND POSSIBLY EPIGENETIC MODIFICATION, AND CAN BE DISTINGUISHED FROM DEVELOPMENTAL DISRUPTION. THE CONCEPT OF PREDICTIVE ADAPTATION HAS BEEN DEVELOPED TO EXPLAIN THE RELATIONSHIP BETWEEN EARLY LIFE EVENTS AND THE RISK OF LATER DISEASE. AT ITS BASE, THE MODEL SUGGESTS THAT A MISMATCH BETWEEN FETAL EXPECTATION OF ITS POSTNATAL ENVIRONMENT AND ACTUAL POSTNATAL ENVIRONMENT CONTRIBUTE TO LATER ADULT DISEASE RISK. THIS MISMATCH IS EXACERBATED, IN PART, BY THE PHENOMENON OF "MATERNAL CONSTRAINT" ON FETAL GROWTH, WHICH IMPLICITLY PROVIDES AN UPPER LIMIT OF POSTNATAL NUTRITIONAL ENVIRONMENT THAT HUMANS HAVE ADAPTED FOR AND IS NOW FREQUENTLY EXCEEDED. THESE EXPERIMENTAL, CLINICAL AND CONCEPTUAL CONSIDERATIONS HAVE IMPORTANT IMPLICATIONS FOR PREVENTION AND INTERVENTION IN THE CURRENT EPIDEMIC OF CHILDHOOD OBESITY AND ADULT METABOLIC AND CARDIOVASCULAR DISORDERS. 2005 15 1938 29 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 16 1409 30 DIETARY INTERVENTIONS AND NUTRITIONAL FACTORS IN THE PREVENTION OF PEDIATRIC ASTHMA. ASTHMA IS THE MOST FREQUENT CHRONIC DISEASE IN CHILDREN, AND ITS PATHOGENESIS INVOLVES GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS. THE RAPID RISE IN THE PREVALENCE OF ASTHMA REGISTERED OVER THE LAST FEW DECADES HAS STRESSED THE NEED TO IDENTIFY THE ENVIRONMENTAL AND MODIFIABLE FACTORS ASSOCIATED WITH THE DEVELOPMENT OF THE DISEASE. IN PARTICULAR, THERE IS INCREASING INTEREST IN THE ROLE OF MODIFIABLE NUTRITIONAL FACTORS SPECIFIC TO BOTH THE PRENATAL AND POST-NATAL EARLY LIFE AS, DURING THIS TIME, THE IMMUNE SYSTEM IS PARTICULARLY VULNERABLE TO EXOGENOUS INTERFERENCES. SEVERAL DIETARY FACTORS, INCLUDING MATERNAL DIET DURING PREGNANCY, THE DURATION OF BREASTFEEDING, THE USE OF SPECIAL MILK FORMULAS, THE TIMING OF THE INTRODUCTION OF COMPLEMENTARY FOODS, AND PRENATAL AND EARLY LIFE SUPPLEMENTATION WITH VITAMINS AND PROBIOTICS/PREBIOTICS, HAVE BEEN ADDRESSED AS POTENTIAL TARGETS FOR THE PREVENTION OF ASTHMA. IN THIS REVIEW, WE OUTLINE RECENT FINDINGS ON THE POTENTIAL ROLE OF PRENATAL AND PERINATAL DIETARY AND NUTRITIONAL INTERVENTIONS FOR THE PRIMARY PREVENTION OF PEDIATRIC ASTHMA. MOREOVER, WE ADDRESSED UNMET NEEDS AND AREAS FOR FUTURE RESEARCH IN THE PREVENTION OF CHILDHOOD-ONSET ASTHMA. 2020 17 46 32 A CONCEPTUAL FRAMEWORK FOR THE DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE. IN THE LAST DECADES, THE DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE (DOHAD) HAVE EMERGED AS A VIGOROUS FIELD COMBINING EXPERIMENTAL, CLINICAL, EPIDEMIOLOGICAL AND PUBLIC HEALTH RESEARCH. ITS GOAL IS TO UNDERSTAND HOW EVENTS IN EARLY LIFE SHAPE LATER MORBIDITY RISK, ESPECIALLY OF NON-COMMUNICABLE CHRONIC DISEASES. AS THESE DISEASES BECOME THE MAJOR CAUSE OF MORBIDITY AND MORTALITY WORLDWIDE, RESEARCH ARISING FROM DOHAD IS LIKELY TO GAIN SIGNIFICANCE TO PUBLIC HEALTH AND ECONOMIC DEVELOPMENT. BUT ACTION MAY BE HINDERED BY THE LACK OF A FIRM MECHANISTIC EXPLANATION AND OF A CONCEPTUAL BASIS, ESPECIALLY REGARDING THE EVOLUTIONARY SIGNIFICANCE OF THE DOHAD PHENOMENON. IN THIS ARTICLE, WE PROVIDE A SUCCINCT HISTORICAL REVIEW OF THE RESEARCH INTO THE RELATIONSHIP BETWEEN DEVELOPMENT AND LATER DISEASE, CONSIDER THE EVOLUTIONARY AND DEVELOPMENTAL SIGNIFICANCE AND DISCUSS THE UNDERLYING MECHANISMS OF THE DOHAD PHENOMENON. DOHAD SHOULD BE VIEWED AS A PART OF A BROADER BIOLOGICAL MECHANISM OF PLASTICITY BY WHICH ORGANISMS, IN RESPONSE TO CUES SUCH AS NUTRITION OR HORMONES, ADAPT THEIR PHENOTYPE TO ENVIRONMENT. THESE RESPONSES MAY BE DIVIDED INTO THOSE FOR IMMEDIATE BENEFIT AND THOSE AIMED AT PREDICTION OF A FUTURE ENVIRONMENT: DISEASE OCCURS IN THE MISMATCH BETWEEN PREDICTED AND REALIZED FUTURE. THE LIKELY MECHANISMS THAT ENABLE PLASTICITY INVOLVE EPIGENETIC PROCESSES, AFFECTING THE EXPRESSION OF GENES ASSOCIATED WITH REGULATORY PATHWAYS. THERE IS NOW EVIDENCE THAT EPIGENETIC MARKS MAY BE INHERITED AND SO CONTRIBUTE TO NON-GENOMIC HERITABLE DISEASE RISK. WE END BY DISCUSSING THE GLOBAL SIGNIFICANCE OF THE DOHAD PHENOMENON AND ITS POTENTIAL APPLICATIONS FOR PUBLIC HEALTH PURPOSES. 2010 18 6864 32 [ORIGINS OF HEALTH AND DISEASE]. OBJECTIVE: TO PRESENT A NEW AREA OF KNOWLEDGE, KNOWN AS DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE, COVERING ITS CONCEPTS, STUDY METHODS AND ETHICAL CONSIDERATIONS. MATERIAL AND METHODS: A REVIEW OF THE MEDICAL LITERATURE INTENDED TO IDENTIFY CURRENT REFERENCES RELATED TO THE SUBJECT UNDER DISCUSSION. RESULTS: THE STUDIES DEMONSTRATE ASSOCIATIONS BETWEEN AGGRESSIONS SUFFERED DURING THE INITIAL PHASES OF SOMATIC DEVELOPMENT AND AMPLIFIED RISK OF CHRONIC DISEASES THROUGHOUT LIFE, SUCH AS OBESITY, DIABETES AND CARDIOVASCULAR DISEASES. A VARIETY OF MODELS HAVE BEEN PROPOSED IN ATTEMPTS TO BETTER EXPLAIN THESE ASSOCIATIONS, SUCH AS THE THRIFTY PHENOTYPE, PROGRAMMING AND PREDICTIVE ADAPTIVE RESPONSE THEORIES AND THE CONCEPT OF MATCH OR MISMATCH. MECHANISMS POSSIBLY INVOLVED IN THESE PROCESSES ARE: EFFECTS OF THE ENVIRONMENT ON GENE EXPRESSION, THROUGH EPIGENETIC MECHANISMS; EFFECTS OF HORMONAL SIGNALS TRANSMITTED TO THE FETUS VIA THE PLACENTA OR THE NEWBORN VIA LACTATION. CONCLUSIONS: DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASES DRAWS TOGETHER INFORMATION ORIGINATING FROM MANY DIFFERENT AREAS OF KNOWLEDGE, PROPOSING NEW INVESTIGATIVE METHODOLOGIES TO ELUCIDATE THE INFLUENCE OF ADVERSE EVENTS THAT OCCUR DURING EARLY PHASES OF HUMAN DEVELOPMENT ON THE PATTERN OF HEALTH AND DISEASE THROUGHOUT LIFE. THIS NEW SCIENTIFIC FIELD PROPOSES NEW MODELS OF CAUSALITY AND OF THE MECHANISMS INVOLVED IN THE EMERGENCE AND DEVELOPMENT OF CHRONIC DISEASES. THE RESULTS OF THESE INVESTIGATIONS MAY RESULT IN A SIGNIFICANT IMPACT ON THE PREVENTION OF CHRONIC DISEASES, AND ALSO ON HEALTH PROMOTION IN DIFFERENT PHASES OF LIFE. 2007 19 2724 33 EXPERIENCE-SENSITIVE EPIGENETIC MECHANISMS, DEVELOPMENTAL PLASTICITY, AND THE BIOLOGICAL EMBEDDING OF CHRONIC DISEASE RISK. A WIDE RANGE OF DEVELOPMENTAL, NUTRITIONAL, ENVIRONMENTAL, AND SOCIAL FACTORS AFFECT THE BIOLOGICAL ACTIVITIES OF EPIGENETIC MECHANISMS. THESE FACTORS CHANGE SPATIOTEMPORAL PATTERNS OF GENE EXPRESSION IN A VARIETY OF DIFFERENT WAYS AND BRING SIGNIFICANT IMPACTS TO BEAR ON DEVELOPMENT, PHYSIOLOGY, AND DISEASE RISK THROUGHOUT THE LIFE COURSE. ABUNDANT EVIDENCE DEMONSTRATES THAT BEHAVIORAL STRESSORS AND ADVERSE NUTRITIONAL CONDITIONS ARE PARTICULARLY POTENT INDUCERS OF EPIGENETIC CHANGES AND ENHANCERS OF CHRONIC DISEASE RISKS. RECENT INSIGHTS FROM BOTH HUMAN CLINICAL STUDIES AND RESEARCH WITH MODEL ORGANISMS FURTHER INDICATE THAT SUCH EXPERIENCE-DEPENDENT CHANGES TO THE EPIGENOME CAN BE TRANSMITTED THROUGH THE GERMLINE ACROSS MULTIPLE GENERATIONS, WITH IMPORTANT CONSEQUENCES FOR THE HERITABILITY OF BOTH ADAPTIVE AND MALADAPTIVE PHENOTYPES. EPIGENETICS RESEARCH THUS OFFERS MANY POSSIBILITIES FOR DEVELOPING INFORMATIVE BIOMARKERS OF ACQUIRED CHRONIC DISEASE RISK AND DETERMINING THE EFFECTIVENESS OF PREVENTIVE AND THERAPEUTIC INTERVENTIONS. MOREOVER, THE EXPERIENCE-SENSITIVE NATURE OF THESE DISEASE RISKS RAISES IMPORTANT QUESTIONS ABOUT SOCIETAL AND INDIVIDUAL RESPONSIBILITIES FOR THE PREVENTION OF ILL-HEALTH AND THE PROMOTION OF WELL-BEING DURING DEVELOPMENT, ACROSS THE LIFE COURSE AND BETWEEN GENERATIONS. BETTER UNDERSTANDING OF HOW EPIGENETIC MECHANISMS REGULATE DEVELOPMENTAL PLASTICITY AND MEDIATE THE BIOLOGICAL EMBEDDING OF CHRONIC DISEASE RISKS IS THEREFORE LIKELY TO SHED IMPORTANT NEW LIGHT ON THE NATURE OF THE PATHOPHYSIOLOGICAL MECHANISMS LINKING SOCIAL AND HEALTH INEQUALITIES, AND WILL HELP TO INFORM PUBLIC POLICY INITIATIVES IN THIS AREA. CONFLICT OF INTEREST: THE AUTHOR HAS DECLARED NO CONFLICTS OF INTEREST FOR THIS ARTICLE. 2015 20 1911 30 ENVIRONMENT IN CHILDREN'S HEALTH: A NEW CHALLENGE FOR RISK ASSESSMENT. IN THE LAST FEW YEARS, MANY STUDIES HAVE FOCUSED ON THE EFFECTS OF ENVIRONMENTAL CONTAMINANT EXPOSURE DURING THE PRENATAL PERIOD OR INFANCY AS PREDICTORS OF HEALTH OUTCOMES IN THE FUTURE. IN THESE TIME WINDOWS, DUE TO THEIR RAPID GROWTH, AND PHYSIOLOGIC AND METABOLIC DEVELOPMENT, WE CAN OBSERVE A HIGHER VULNERABILITY TO THE EFFECTS OF ENVIRONMENT, WITH RESPECT TO ADULTHOOD. THE EVIDENCE OF POSSIBLE INFLUENCES, PARTLY MEDIATED BY EPIGENETIC MECHANISMS, INVOLVE NEUROBEHAVIORAL RESPONSES AND IMMUNE, ENDOCRINE, AND RESPIRATORY SYSTEMS, ACTING DIRECTLY ON THE CHILD OR INDIRECTLY WHEN MEDIATED BY PLACENTAL TRANSFER OR BREAST FEEDING. IN PARTICULAR, DUE TO A GREATER INTAKE OF AIR, FOOD, AND FLUIDS RELATIVE TO BODY WEIGHT, CRAWLING BEHAVIORS AND SHORT STATURE, THE RISK OF EXCESSIVE EXPOSURE IS GREATER IN CHILDREN. HOWEVER, DATA ON THE LONG-TERM IMPLICATIONS OF EARLY EXPOSURES ARE SCARCE. ADDITIONALLY, SO THAT PHYSICIANS AND INSTITUTIONS FOR CHILD CARE AND ASSISTANCE OF PREGNANT WOMEN CAN TAKE ACTIONS TO COUNTERACT THE EFFECTS OF CHEMICAL POLLUTION (I.E., BY EDUCATIONAL OPPORTUNITIES), A RISK ASSESSMENT PERSPECTIVE THAT RESPONDS TO THE BIOCOMPLEXITY OF THE HUMAN BEING IS NEEDED. THE PRESENT PAPER PROVIDES AN OVERVIEW OF PHYSIOLOGIC AND BEHAVIORAL CHARACTERISTICS DURING THE PERINATAL PERIOD AND IN CHILDHOOD, SUGGESTING IN A MORE INTEGRATED WAY, THE NEED OF A NEW RISK-ASSESSMENT APPROACH TO MANAGING CHRONIC DISEASE IN PEDIATRIC PATIENTS. 2021