1 270 113 AGE AND SUN EXPOSURE-RELATED WIDESPREAD GENOMIC BLOCKS OF HYPOMETHYLATION IN NONMALIGNANT SKIN. BACKGROUND: AGING AND SUN EXPOSURE ARE THE LEADING CAUSES OF SKIN CANCER. IT HAS BEEN SHOWN THAT EPIGENETIC CHANGES, SUCH AS DNA METHYLATION, ARE WELL ESTABLISHED MECHANISMS FOR CANCER, AND ALSO HAVE EMERGING ROLES IN AGING AND COMMON DISEASE. HERE, WE DIRECTLY ASK WHETHER DNA METHYLATION IS ALTERED FOLLOWING SKIN AGING AND/OR CHRONIC SUN EXPOSURE IN HUMANS. RESULTS: WE COMPARE EPIDERMIS AND DERMIS OF BOTH SUN-PROTECTED AND SUN-EXPOSED SKIN DERIVED FROM YOUNGER SUBJECTS (UNDER 35 YEARS OLD) AND OLDER SUBJECTS (OVER 60 YEARS OLD), USING THE INFINIUM HUMANMETHYLATION450 ARRAY AND WHOLE GENOME BISULFITE SEQUENCING. WE OBSERVE LARGE BLOCKS OF THE GENOME THAT ARE HYPOMETHYLATED IN OLDER, SUN-EXPOSED EPIDERMAL SAMPLES, WITH THE DEGREE OF HYPOMETHYLATION ASSOCIATED WITH CLINICAL MEASURES OF PHOTO-AGING. WE REPLICATE THESE FINDINGS USING WHOLE GENOME BISULFITE SEQUENCING, COMPARING EPIDERMIS FROM AN ADDITIONAL SET OF YOUNGER AND OLDER SUBJECTS. THESE BLOCKS LARGELY OVERLAP KNOWN HYPOMETHYLATED BLOCKS IN COLON CANCER AND WE OBSERVE THAT THESE SAME REGIONS ARE SIMILARLY HYPOMETHYLATED IN SQUAMOUS CELL CARCINOMA SAMPLES. CONCLUSIONS: THESE DATA IMPLICATE LARGE SCALE EPIGENOMIC CHANGE IN MEDIATING THE EFFECTS OF ENVIRONMENTAL DAMAGE WITH PHOTO-AGING. 2015 2 287 33 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 3 1345 31 DETECTION OF DIFFERENTIALLY METHYLATED REGIONS USING BAYES FACTOR FOR ORDINAL GROUP RESPONSES. RESEARCHERS IN GENOMICS ARE INCREASINGLY INTERESTED IN EPIGENETIC FACTORS SUCH AS DNA METHYLATION, BECAUSE THEY PLAY AN IMPORTANT ROLE IN REGULATING GENE EXPRESSION WITHOUT CHANGES IN THE DNA SEQUENCE. THERE HAVE BEEN SIGNIFICANT ADVANCES IN DEVELOPING STATISTICAL METHODS TO DETECT DIFFERENTIALLY METHYLATED REGIONS (DMRS) ASSOCIATED WITH BINARY DISEASE STATUS. MOST OF THESE METHODS ARE BEING DEVELOPED FOR DETECTING DIFFERENTIAL METHYLATION RATES BETWEEN CASES AND CONTROLS. WE CONSIDER MULTIPLE SEVERITY LEVELS OF DISEASE, AND DEVELOP A BAYESIAN STATISTICAL METHOD TO DETECT THE REGION WITH INCREASING (OR DECREASING) METHYLATION RATES AS THE DISEASE SEVERITY INCREASES. PATIENTS ARE CLASSIFIED INTO MORE THAN TWO GROUPS, BASED ON THE DISEASE SEVERITY (E.G., STAGES OF CANCER), AND DMRS ARE DETECTED BY USING MOVING WINDOWS ALONG THE GENOME. WITHIN EACH WINDOW, THE BAYES FACTOR IS CALCULATED TO TEST THE HYPOTHESIS OF MONOTONIC INCREASE IN METHYLATION RATES CORRESPONDING TO SEVERITY OF THE DISEASE VERSUS NO DIFFERENCE. A MIXED-EFFECT MODEL IS USED TO INCORPORATE THE CORRELATION OF METHYLATION RATES OF NEARBY CPG SITES IN THE REGION. RESULTS FROM EXTENSIVE SIMULATION INDICATE THAT OUR PROPOSED METHOD IS STATISTICALLY VALID AND REASONABLY POWERFUL. WE DEMONSTRATE OUR APPROACH ON A BISULFITE SEQUENCING DATASET FROM A CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) STUDY. 2019 4 6083 38 THE EFFECT OF SMOKING ON DNA METHYLATION OF PERIPHERAL BLOOD MONONUCLEAR CELLS FROM AFRICAN AMERICAN WOMEN. BACKGROUND: REGULAR SMOKING IS ASSOCIATED WITH A WIDE VARIETY OF SYNDROMES WITH PROMINENT INFLAMMATORY COMPONENTS SUCH AS CANCER, OBESITY AND TYPE 2 DIABETES. HEAVY REGULAR SMOKING IS ALSO ASSOCIATED WITH CHANGES IN THE DNA METHYLATION OF PERIPHERAL MONONUCLEAR CELLS. HOWEVER, IN YOUNGER SMOKERS, INFLAMMATORY EPIGENETIC FINDINGS ARE LARGELY ABSENT WHICH SUGGESTS THE INFLAMMATORY RESPONSE(S) TO SMOKING MAY BE DOSE DEPENDENT. TO HELP UNDERSTAND WHETHER PERIPHERAL MONONUCLEAR CELLS HAVE A ROLE IN MEDIATING THESE RESPONSES IN OLDER SMOKERS WITH HIGHER CUMULATIVE SMOKE EXPOSURE, WE EXAMINED GENOME-WIDE DNA METHYLATION IN A GROUP OF WELL CHARACTERIZED ADULT AFRICAN AMERICAN SUBJECTS INFORMATIVE FOR SMOKING, AS WELL AS SERUM C-REACTIVE PROTEIN (CRP) AND INTERLEUKIN-6 RECEPTOR (IL6R) LEVELS. IN ADDITION, COMPLEMENTARY BIOINFORMATIC ANALYSES WERE CONDUCTED TO DELINEATE POSSIBLE PATHWAYS AFFECTED BY LONG-TERM SMOKING. RESULTS: GENOME-WIDE DNA METHYLATION ANALYSIS WITH RESPECT TO SMOKING STATUS YIELDED 910 SIGNIFICANT LOCI AFTER BENJAMINI-HOCHBERG CORRECTION. IN PARTICULAR, TWO LOCI FROM THE AHRR GENE (CG05575921 AND CG23576855) AND ONE LOCUS FROM THE GPR15 GENE (CG19859270) WERE IDENTIFIED AS HIGHLY SIGNIFICANTLY DIFFERENTIALLY METHYLATED BETWEEN SMOKERS AND NON-SMOKERS. THE BIOINFORMATIC ANALYSES SHOWED THAT LONG-TERM CHRONIC SMOKING IS ASSOCIATED WITH ALTERED PROMOTER DNA METHYLATION OF GENES CODING FOR PROTEINS MAPPING TO CRITICAL SUB-NETWORKS MODERATING INFLAMMATION, IMMUNE FUNCTION, AND COAGULATION. CONCLUSIONS: WE CONCLUDE THAT CHRONIC REGULAR SMOKING IS ASSOCIATED WITH CHANGES IN PERIPHERAL MONONUCLEAR CELL METHYLATION SIGNATURE WHICH PERTURB INFLAMMATORY AND IMMUNE FUNCTION PATHWAYS AND MAY CONTRIBUTE TO INCREASED VULNERABILITY FOR COMPLEX ILLNESSES WITH INFLAMMATORY COMPONENTS. 2014 5 6311 31 THE RELATION BETWEEN DNA METHYLATION PATTERNS AND SERUM CYTOKINE LEVELS IN COMMUNITY-DWELLING ADULTS: A PRELIMINARY STUDY. BACKGROUND: THE LEVELS OF CIRCULATING CYTOKINES FLUCTUATE WITH AGE, ACUTE ILLNESS, AND CHRONIC DISEASE, AND ARE PREDICTIVE OF MORTALITY; THIS IS ALSO TRUE FOR PATTERNS OF DNA (CPG) METHYLATION. GIVEN THAT IMMUNE CELLS ARE PARTICULARLY SENSITIVE TO CHANGES IN THE CONCENTRATION OF CYTOKINES IN THEIR MICROENVIRONMENT, WE HYPOTHESIZED THAT SERUM LEVELS OF TNF, IL-6, IL-8 AND IL-10 WOULD CORRELATE WITH GENOME-WIDE ALTERATIONS IN THE DNA METHYLATION LEVELS OF BLOOD LEUKOCYTES. TO TEST THIS, WE EVALUATED COMMUNITY-DWELLING ADULTS (N = 14; 48-78 YEARS OLD) RECRUITED TO A PILOT STUDY FOR THE CANADIAN LONGITUDINAL STUDY ON AGING (CLSA), EXAMINING DNA METHYLATION PATTERNS IN PERIPHERAL BLOOD MONONUCLEAR CELLS USING THE ILLUMINA HUMANMETHYLATION 450 K BEADCHIP. RESULTS: WE SHOW THAT, APART FROM AGE, SERUM IL-10 LEVELS EXHIBITED THE MOST SUBSTANTIAL ASSOCIATION TO DNA METHYLATION PATTERNS, FOLLOWED BY TNF, IL-6 AND IL-8. FURTHERMORE, WHILE THE LEVELS OF THESE CYTOKINES WERE HIGHER IN ELDERLY ADULTS, NO ASSOCIATIONS WITH EPIGENETIC ACCELERATED AGING, DERIVED USING THE EPIGENETIC CLOCK, WERE OBSERVED. CONCLUSIONS: AS A PRELIMINARY STUDY WITH A SMALL SAMPLE SIZE, THE CONCLUSIONS DRAWN FROM THIS WORK MUST BE VIEWED WITH CAUTION; HOWEVER, OUR OBSERVATIONS ARE ENCOURAGING AND CERTAINLY WARRANT MORE SUITABLY POWERED STUDIES OF THIS RELATIONSHIP. 2017 6 3652 26 INDIVIDUAL DNA METHYLATION PATTERN SHIFTS IN NANOPARTICLES-EXPOSED WORKERS ANALYZED IN FOUR CONSECUTIVE YEARS. A DNA METHYLATION PATTERN REPRESENTS AN ORIGINAL PLAN OF THE FUNCTION SETTINGS OF INDIVIDUAL CELLS AND TISSUES. THE BASIC STRATEGIES OF ITS DEVELOPMENT AND CHANGES DURING THE HUMAN LIFETIME ARE KNOWN, BUT THE DETAILS RELATED TO ITS MODIFICATION OVER THE YEARS ON AN INDIVIDUAL BASIS HAVE NOT YET BEEN STUDIED. MOREOVER, CURRENT EVIDENCE SHOWS THAT ENVIRONMENTAL EXPOSURE COULD GENERATE CHANGES IN DNA METHYLATION SETTINGS AND, SUBSEQUENTLY, THE FUNCTION OF GENES. IN THIS STUDY, WE ANALYZED THE EFFECT OF CHRONIC EXPOSURE TO NANOPARTICLES (NP) IN OCCUPATIONALLY EXPOSED WORKERS REPEATEDLY SAMPLED IN FOUR CONSECUTIVE YEARS (2016-2019). A DETAILED METHYLATION PATTERN ANALYSIS OF 14 PERSONS (10 EXPOSED AND 4 CONTROLS) WAS PERFORMED ON AN INDIVIDUAL BASIS. A MICROARRAY-BASED APPROACH USING CHIPS, ALLOWING THE ASSESSMENT OF MORE THAN 850 K CPG LOCI, WAS USED. INDIVIDUAL DNA METHYLATION PATTERNS WERE COMPARED BY PRINCIPAL COMPONENT ANALYSIS (PCA). THE RESULTS SHOW THE SHIFT IN DNA METHYLATION PATTERNS IN INDIVIDUAL YEARS IN ALL THE EXPOSED AND CONTROL SUBJECTS. THE OVERALL RANGE OF DIFFERENCES VARIED BETWEEN THE YEARS IN INDIVIDUAL PERSONS. THE DIFFERENCES BETWEEN THE FIRST AND LAST YEAR OF EXAMINATION (A THREE-YEAR TIME PERIOD) SEEM TO BE CONSISTENTLY GREATER IN THE NP-EXPOSED SUBJECTS IN COMPARISON WITH THE CONTROLS. THE SELECTED 14 MOST DIFFERENTLY METHYLATED CG LOCI WERE RELATIVELY STABLE IN THE CHRONICALLY EXPOSED SUBJECTS. IN SUMMARY, THE SPECIFIC TYPE OF LONG-TERM EXPOSURE CAN CONTRIBUTE TO THE FIXING OF RELEVANT EPIGENETIC CHANGES RELATED TO A SPECIFIC ENVIRONMENT AS, E.G., NP INHALATION. 2021 7 1583 25 DNA METHYLATION PROFILES OF BLOOD CELLS ARE DISTINCT BETWEEN EARLY-ONSET OBESE AND CONTROL INDIVIDUALS. OBESITY IS A HIGHLY PREVALENT, CHRONIC DISORDER THAT HAS BEEN INCREASING IN INCIDENCE IN YOUNG PATIENTS. BOTH EPIGENETIC AND GENETIC ABERRATIONS MAY PLAY A ROLE IN THE PATHOGENESIS OF OBESITY. THEREFORE, IN-DEPTH EPIGENOMIC AND GENOMIC ANALYSES WILL ADVANCE OUR UNDERSTANDING OF THE DETAILED MOLECULAR MECHANISMS UNDERLYING OBESITY AND AID IN THE SELECTION OF POTENTIAL BIOMARKERS FOR OBESITY IN YOUTH. HERE, WE PERFORMED MICROARRAY-BASED DNA METHYLATION AND GENE EXPRESSION PROFILING OF PERIPHERAL WHITE BLOOD CELLS OBTAINED FROM SIX YOUNG, OBESE INDIVIDUALS AND SIX HEALTHY CONTROLS. WE OBSERVED THAT THE HIERARCHICAL CLUSTERING OF DNA METHYLATION, BUT NOT GENE EXPRESSION, CLEARLY SEGREGATES THE OBESE INDIVIDUALS FROM THE CONTROLS, SUGGESTING THAT THE METABOLIC DISTURBANCE THAT OCCURS AS A RESULT OF OBESITY AT A YOUNG AGE MAY AFFECT THE DNA METHYLATION OF PERIPHERAL BLOOD CELLS WITHOUT ACCOMPANYING TRANSCRIPTIONAL CHANGES. TO EXAMINE THE GENOME-WIDE DIFFERENCES IN THE DNA METHYLATION PROFILES OF YOUNG OBESE AND CONTROL INDIVIDUALS, WE IDENTIFIED DIFFERENTIALLY METHYLATED CPG SITES AND INVESTIGATED THEIR GENOMIC AND EPIGENOMIC CONTEXTS. THE ABERRANT DNA METHYLATION PATTERNS IN OBESE INDIVIDUALS CAN BE SUMMARIZED AS RELATIVE GAINS AND LOSSES OF DNA METHYLATION IN GENE PROMOTERS AND GENE BODIES, RESPECTIVELY. WE ALSO OBSERVED THAT THE CPG ISLANDS OF OBESE INDIVIDUALS ARE MORE SUSCEPTIBLE TO DNA METHYLATION COMPARED TO CONTROLS. OUR PILOT STUDY SUGGESTS THAT THE GENOME-WIDE ABERRANT DNA METHYLATION PATTERNS OF OBESE INDIVIDUALS MAY ADVANCE NOT ONLY OUR UNDERSTANDING OF THE EPIGENOMIC PATHOGENESIS BUT ALSO EARLY SCREENING OF OBESITY IN YOUTH. 2017 8 1705 31 DYNAMICS OF SMOKING-INDUCED GENOME-WIDE METHYLATION CHANGES WITH TIME SINCE SMOKING CESSATION. SEVERAL STUDIES HAVE RECENTLY IDENTIFIED STRONG EPIGENETIC SIGNALS RELATED TO TOBACCO SMOKING. HOWEVER, AN ASPECT THAT DID NOT RECEIVE MUCH ATTENTION IS THE EVOLUTION OF EPIGENETIC CHANGES WITH TIME SINCE SMOKING CESSATION. WE CONDUCTED A SERIES OF EPIGENOME-WIDE ASSOCIATION STUDIES TO CAPTURE THE DYNAMICS OF SMOKING-INDUCED EPIGENETIC CHANGES AFTER SMOKING CESSATION, USING GENOME-WIDE METHYLATION PROFILES OBTAINED FROM BLOOD SAMPLES IN 745 WOMEN FROM 2 EUROPEAN POPULATIONS. TWO DISTINCT CLASSES OF CPG SITES WERE IDENTIFIED: SITES WHOSE METHYLATION REVERTS TO LEVELS TYPICAL OF NEVER SMOKERS WITHIN DECADES AFTER SMOKING CESSATION, AND SITES REMAINING DIFFERENTIALLY METHYLATED, EVEN MORE THAN 35 YEARS AFTER SMOKING CESSATION. OUR RESULTS SUGGEST THAT THE DYNAMICS OF METHYLATION CHANGES FOLLOWING SMOKING CESSATION ARE DRIVEN BY A DIFFERENTIAL AND SITE-SPECIFIC MAGNITUDE OF THE SMOKING-INDUCED ALTERATIONS (WITH PERSISTENT SITES BEING MOST AFFECTED) IRRESPECTIVE OF THE INTENSITY AND DURATION OF SMOKING. ANALYSES OF THE LINK BETWEEN METHYLATION AND EXPRESSION LEVELS REVEALED THAT METHYLATION PREDOMINANTLY AND REMOTELY DOWN-REGULATES GENE EXPRESSION. AMONG GENES WHOSE EXPRESSION WAS ASSOCIATED WITH OUR CANDIDATE CPG SITES, LRRN3 APPEARED TO BE PARTICULARLY INTERESTING AS IT WAS ONE OF THE FEW GENES WHOSE METHYLATION AND EXPRESSION WERE DIRECTLY ASSOCIATED, AND THE ONLY GENE IN WHICH BOTH METHYLATION AND GENE EXPRESSION WERE FOUND ASSOCIATED WITH SMOKING. OUR STUDY HIGHLIGHTS PERSISTENT EPIGENETIC MARKERS OF SMOKING, WHICH CAN POTENTIALLY BE DETECTED DECADES AFTER CESSATION. SUCH HISTORICAL SIGNATURES ARE PROMISING BIOMARKERS TO REFINE INDIVIDUAL RISK PROFILING OF SMOKING-INDUCED CHRONIC DISEASE SUCH AS LUNG CANCER. 2015 9 1503 31 DNA METHYLATION AND GENE EXPRESSION DIFFERENCES IN CHILDREN CONCEIVED IN VITRO OR IN VIVO. EPIDEMIOLOGICAL DATA INDICATE THAT CHILDREN CONCEIVED IN VITRO HAVE A GREATER RELATIVE RISK OF LOW BIRTH-WEIGHT, MAJOR AND MINOR BIRTH DEFECTS, AND RARE DISORDERS INVOLVING IMPRINTED GENES, SUGGESTING THAT EPIGENETIC CHANGES MAY BE ASSOCIATED WITH ASSISTED REPRODUCTION. WE EXAMINED DNA METHYLATION AT MORE THAN 700 GENES (1536 CPG SITES) IN PLACENTA AND CORD BLOOD AND MEASURED GENE EXPRESSION LEVELS OF A SUBSET OF GENES THAT DIFFERED IN METHYLATION LEVELS BETWEEN CHILDREN CONCEIVED IN VITRO VERSUS IN VIVO. OUR RESULTS SUGGEST THAT IN VITRO CONCEPTION IS ASSOCIATED WITH LOWER MEAN METHYLATION AT CPG SITES IN PLACENTA AND HIGHER MEAN METHYLATION AT CPG SITES IN CORD BLOOD. WE ALSO FIND THAT IN VITRO CONCEPTION-ASSOCIATED DNA METHYLATION DIFFERENCES ARE ASSOCIATED WITH GENE EXPRESSION DIFFERENCES AT BOTH IMPRINTED AND NON-IMPRINTED GENES. THE RANGE OF INTER-INDIVIDUAL VARIATION IN GENE EXPRESSION OF THE IN VITRO AND IN VIVO GROUPS OVERLAPS SUBSTANTIALLY BUT SOME INDIVIDUALS FROM THE IN VITRO GROUP DIFFER FROM THE IN VIVO GROUP MEAN BY MORE THAN TWO STANDARD DEVIATIONS. SEVERAL OF THE GENES WHOSE EXPRESSION DIFFERS BETWEEN THE TWO GROUPS HAVE BEEN IMPLICATED IN CHRONIC METABOLIC DISORDERS, SUCH AS OBESITY AND TYPE II DIABETES. THESE FINDINGS SUGGEST THAT THERE MAY BE EPIGENETIC DIFFERENCES IN THE GAMETES OR EARLY EMBRYOS DERIVED FROM COUPLES UNDERGOING TREATMENT FOR INFERTILITY. ALTERNATIVELY, ASSISTED REPRODUCTION TECHNOLOGY MAY HAVE AN EFFECT ON GLOBAL PATTERNS OF DNA METHYLATION AND GENE EXPRESSION. IN EITHER CASE, THESE DIFFERENCES OR CHANGES MAY AFFECT LONG-TERM PATTERNS OF GENE EXPRESSION. 2009 10 1519 25 DNA METHYLATION AT ATP11A CG11702988 IS A BIOMARKER OF LUNG DISEASE SEVERITY IN CYSTIC FIBROSIS: A LONGITUDINAL STUDY. CYSTIC FIBROSIS (CF) IS A CHRONIC GENETIC DISEASE THAT MAINLY AFFECTS THE RESPIRATORY AND GASTROINTESTINAL SYSTEMS. NO CURATIVE TREATMENTS ARE AVAILABLE, BUT THE FOLLOW-UP IN SPECIALIZED CENTERS HAS GREATLY IMPROVED THE PATIENT LIFE EXPECTANCY. ROBUST BIOMARKERS ARE REQUIRED TO MONITOR THE DISEASE, GUIDE TREATMENTS, STRATIFY PATIENTS, AND PROVIDE OUTCOME MEASURES IN CLINICAL TRIALS. IN THE PRESENT STUDY, WE OUTLINE A STRATEGY TO SELECT PUTATIVE DNA METHYLATION BIOMARKERS OF LUNG DISEASE SEVERITY IN CYSTIC FIBROSIS PATIENTS. IN THE DISCOVERY STEP, WE SELECTED SEVEN POTENTIAL BIOMARKERS USING A GENOME-WIDE DNA METHYLATION DATASET THAT WE GENERATED IN NASAL EPITHELIAL SAMPLES FROM THE METHYLCF COHORT. IN THE REPLICATION STEP, WE ASSESSED THE SAME BIOMARKERS USING SPUTUM CELL SAMPLES FROM THE METHYLBIOMARK COHORT. OF INTEREST, DNA METHYLATION AT THE CG11702988 SITE (ATP11A GENE) POSITIVELY CORRELATED WITH LUNG FUNCTION AND BMI, AND NEGATIVELY CORRELATED WITH LUNG DISEASE SEVERITY, P. AERUGINOSA CHRONIC INFECTION, AND THE NUMBER OF EXACERBATIONS. THESE RESULTS WERE REPLICATED IN PROSPECTIVE SPUTUM SAMPLES COLLECTED AT FOUR TIME POINTS WITHIN AN 18-MONTH PERIOD AND LONGITUDINALLY. TO CONCLUDE, (I) WE IDENTIFIED A DNA METHYLATION BIOMARKER THAT CORRELATES WITH CF SEVERITY, (II) WE PROVIDED A METHOD TO EASILY ASSESS THIS BIOMARKER, AND (III) WE CARRIED OUT THE FIRST LONGITUDINAL ANALYSIS OF DNA METHYLATION IN CF PATIENTS. THIS NEW EPIGENETIC BIOMARKER COULD BE USED TO STRATIFY CF PATIENTS IN CLINICAL TRIALS. 2021 11 2483 25 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 12 1587 29 DNA METHYLATION PROFILING IDENTIFIES NOVEL MARKERS OF PROGRESSION IN HEPATITIS B-RELATED CHRONIC LIVER DISEASE. BACKGROUND: CHRONIC HEPATITIS B INFECTION IS CHARACTERIZED BY HEPATIC IMMUNE AND INFLAMMATORY RESPONSE WITH CONSIDERABLE VARIATION IN THE RATES OF PROGRESSION TO CIRRHOSIS. GENETIC VARIANTS AND ENVIRONMENTAL CUES INFLUENCE PREDISPOSITION TO THE DEVELOPMENT OF CHRONIC LIVER DISEASE; HOWEVER, IT REMAINS UNKNOWN IF ABERRANT DNA METHYLATION IS ASSOCIATED WITH FIBROSIS PROGRESSION IN CHRONIC HEPATITIS B. RESULTS: TO IDENTIFY EPIGENETIC MARKS ASSOCIATED WITH INFLAMMATORY AND FIBROTIC PROCESSES OF THE HEPATITIS B-INDUCED CHRONIC LIVER DISEASE, WE CARRIED OUT HEPATIC GENOME-WIDE METHYLATION PROFILING USING ILLUMINA INFINIUM BEADARRAYS COMPARING MILD AND SEVERE FIBROTIC DISEASE IN A DISCOVERY COHORT OF 29 PATIENTS. WE OBTAINED 310 DIFFERENTIALLY METHYLATED REGIONS AND SELECTED FOUR LOCI COMPRISING THREE GENES FROM THE TOP DIFFERENTIALLY METHYLATED REGIONS: HYPERMETHYLATION OF HOXA2 AND HDAC4 ALONG WITH HYPOMETHYLATION OF PPP1R18 WERE SIGNIFICANTLY LINKED TO SEVERE FIBROSIS. WE REPLICATED THE PROMINENT METHYLATION MARKS IN AN INDEPENDENT COHORT OF 102 PATIENTS BY BISULFITE MODIFICATION AND PYROSEQUENCING. THE TIMING AND CAUSAL RELATIONSHIP OF EPIGENETIC MODIFICATIONS WITH DISEASE SEVERITY WAS FURTHER INVESTIGATED USING A COHORT OF PATIENTS WITH SERIAL BIOPSIES. CONCLUSIONS: OUR FINDINGS SUGGEST A LINKAGE OF WIDESPREAD EPIGENETIC DYSREGULATION WITH DISEASE PROGRESSION IN CHRONIC HEPATITIS B INFECTION. CPG METHYLATION AT NOVEL GENES SHEDS LIGHT ON NEW MOLECULAR PATHWAYS, WHICH CAN BE POTENTIALLY EXPLOITED AS A BIOMARKER OR TARGETED TO ATTENUATE INFLAMMATION AND FIBROSIS. 2016 13 6845 29 [METHYLATION STATUS OF APOPTOSIS GENES AND INTENSITY OF APOPTOTIC DEATH OF PERIPHERAL BLOOD LYMPHOCYTES IN PERSONS CHRONICALLY EXPOSED TO RADIATION]. METHYLATION OF THE CPG ISLANDS OF GENE PROMOTER REGIONS IS THE MOST COMMON EPIGENETIC MODIFICATION INVOLVED IN THE REGULATION OF GENE EXPRESSION. A NUMBER OF STUDIES HAVE SHOWN THAT IONIZING RADIATION CAN CAUSE BOTH HYPER- AND HYPOMETHYLATION OF DNA. ABERRANT METHYLATION AFFECTS CELLULAR PROCESSES AND CAN LEAD TO THE DEVELOPMENT OF VARIOUS PATHOLOGICAL STATES. IN THE LITERATURE, THERE ARE FEW STUDIES ON THE METHYLATION STATUS OF HUMAN DNA A LONG TIME AFTER RADIATION EXPOSURE. HERE, THE METHYLATION LEVEL OF CPG ISLANDS OF THE PROMOTER REGIONS OF APOPTOSIS GENES (BCL2, ATM, MDM2, CDKN1A, STAT3, AND NFKB1), AND ALSO ITS INFLUENCE ON APOPTOSIS OF PERIPHERAL BLOOD LYMPHOCYTES IN CHRONICALLY EXPOSED PERSONS WERE STUDIED. RESIDENTS OF THE SOUTH URAL REGION WHO WERE CHRONICALLY EXPOSED TO RADIATION (AFTER DISCHARGES OF RADIOACTIVE WASTES INTO THE TECHA RIVER BY THE "MAYAK PRODUCTION ASSOCIATION" IN 1949-1956) WERE INCLUDED IN THE STUDY. IT WAS ESTABLISHED THAT THE PROPORTION OF INDIVIDUALS WITH HYPERMETHYLATED BCL2 GENE PROMOTER AMONG THE EXPOSED PEOPLE WAS STATISTICALLY SIGNIFICANTLY HIGHER THAN IN THE CONTROL GROUP. THE PERCENTAGE OF METHYLATION OF THE ATM GENE PROMOTER WEAKLY POSITIVELY CORRELATED WITH DOSE AND AGE CHARACTERISTICS. DIFFERENCES IN THE FREQUENCY OF LYMPHOCYTE APOPTOSIS IN EXPOSED INDIVIDUALS WITH A HYPO- OR HYPERMETHYLATED ATM GENE PROMOTER WERE ALSO ESTABLISHED. THE DATA INDICATE THAT, IN THE LONG-TERM, AFTER CHRONIC LOW INTENSITY RADIATION EXPOSURE AT LOW AND MEDIUM DOSES, EPIGENETIC MODIFICATIONS OF THE GENOME OCCUR, WHICH ARE MANIFESTED AS CHANGES IN METHYLATION OF PROMOTER REGIONS OF BCL2 AND ATM GENES. 2022 14 1537 27 DNA METHYLATION IN ADOLESCENTS WITH ANXIETY DISORDER: A LONGITUDINAL STUDY. ANXIETY DISORDERS (AD) TYPICALLY MANIFEST IN CHILDREN AND ADOLESCENTS AND MIGHT PERSIST INTO ADULTHOOD. HOWEVER, THERE ARE STILL FEW DATA CONCERNING EPIGENETIC MECHANISMS ASSOCIATED WITH ONSET, PERSISTENCE OR REMISSION OF AD OVER TIME. WE INVESTIGATED A COHORT OF ADOLESCENTS AND YOUNG ADULTS AT BASELINE (AGE; 13.19 +/- 2.38) AND AFTER 5 YEARS AND CLASSIFIED THEM ACCORDING TO THE AD DIAGNOSIS AND THEIR LONGITUDINAL TRAJECTORIES INTO 4 GROUPS: (1) TYPICALLY DEVELOPING COMPARISONS (TDC; CONTROL GROUP, N = 14); (2) INCIDENT (AD IN THE SECOND EVALUATION ONLY, N = 11); (3) PERSISTENT (AD IN BOTH EVALUATIONS, N = 14) AND (4) REMITTENT (AD IN THE FIRST EVALUATION ONLY, N = 8). DNA METHYLATION WAS EVALUATED WITH THE INFINIUM HUMANMETHYLATION450 BEADCHIP FROM SALIVA SAMPLES COLLECTED AT BOTH EVALUATIONS. GENE SET ENRICHMENT ANALYSIS WAS APPLIED TO CONSIDER BIOLOGICAL PATHWAYS. WE FOUND DECREASED DNA METHYLATION IN TDC GROUP WHILE THE CHRONIC CASES OF AD PRESENTED HYPERMETHYLATION IN CENTRAL NERVOUS SYSTEM DEVELOPMENT PATHWAYS. MOREOVER, WE SHOWED THAT THIS PERSISTENT GROUP ALSO PRESENTED HYPERMETHYLATION WHILE THE OTHER THREE GROUPS WERE ASSOCIATED WITH HYPOMETHYLATION IN NERVOUS SYSTEM DEVELOPMENT PATHWAY. INCIDENCE AND REMISSION GROUPS WERE ASSOCIATED WITH INCREASED AND DECREASED METHYLATION IN NEURON DEVELOPMENT PATHWAYS, RESPECTIVELY. LARGER STUDIES ARE LIKELY TO DETECT SPECIFIC GENES RELEVANT TO AD. 2018 15 4255 26 METHYLOME-WIDE ANALYSIS OF CHRONIC HIV INFECTION REVEALS FIVE-YEAR INCREASE IN BIOLOGICAL AGE AND EPIGENETIC TARGETING OF HLA. HIV-INFECTED INDIVIDUALS ARE LIVING LONGER ON ANTIRETROVIRAL THERAPY, BUT MANY PATIENTS DISPLAY SIGNS THAT IN SOME WAYS RESEMBLE PREMATURE AGING. TO INVESTIGATE AND QUANTIFY THE IMPACT OF CHRONIC HIV INFECTION ON AGING, WE REPORT A GLOBAL ANALYSIS OF THE WHOLE-BLOOD DNA METHYLOMES OF 137 HIV+ INDIVIDUALS UNDER SUSTAINED THERAPY ALONG WITH 44 MATCHED HIV- INDIVIDUALS. FIRST, WE DEVELOP AND VALIDATE EPIGENETIC MODELS OF AGING THAT ARE INDEPENDENT OF BLOOD CELL COMPOSITION. USING THESE MODELS, WE FIND THAT BOTH CHRONIC AND RECENT HIV INFECTION LEAD TO AN AVERAGE AGING ADVANCEMENT OF 4.9 YEARS, INCREASING EXPECTED MORTALITY RISK BY 19%. IN ADDITION, SUSTAINED INFECTION RESULTS IN GLOBAL DEREGULATION OF THE METHYLOME ACROSS >80,000 CPGS AND SPECIFIC HYPOMETHYLATION OF THE REGION ENCODING THE HUMAN LEUKOCYTE ANTIGEN LOCUS (HLA). WE FIND THAT DECREASED HLA METHYLATION IS PREDICTIVE OF LOWER CD4 / CD8 T CELL RATIO, LINKING MOLECULAR AGING, EPIGENETIC REGULATION, AND DISEASE PROGRESSION. 2016 16 1739 33 EARLY DNA METHYLATION CHANGES IN CHILDREN DEVELOPING BETA CELL AUTOIMMUNITY AT A YOUNG AGE. AIMS/HYPOTHESIS: TYPE 1 DIABETES IS A CHRONIC AUTOIMMUNE DISEASE OF COMPLEX AETIOLOGY, INCLUDING A POTENTIAL ROLE FOR EPIGENETIC REGULATION. PREVIOUS EPIGENOMIC STUDIES FOCUSED MAINLY ON CLINICALLY DIAGNOSED INDIVIDUALS. THE AIM OF THE STUDY WAS TO ASSESS EARLY DNA METHYLATION CHANGES ASSOCIATED WITH TYPE 1 DIABETES ALREADY BEFORE THE DIAGNOSIS OR EVEN BEFORE THE APPEARANCE OF AUTOANTIBODIES. METHODS: REDUCED REPRESENTATION BISULPHITE SEQUENCING (RRBS) WAS APPLIED TO STUDY DNA METHYLATION IN PURIFIED CD4(+) T CELL, CD8(+) T CELL AND CD4(-)CD8(-) CELL FRACTIONS OF 226 PERIPHERAL BLOOD MONONUCLEAR CELL SAMPLES LONGITUDINALLY COLLECTED FROM SEVEN TYPE 1 DIABETES-SPECIFIC AUTOANTIBODY-POSITIVE INDIVIDUALS AND CONTROL INDIVIDUALS MATCHED FOR AGE, SEX, HLA RISK AND PLACE OF BIRTH. WE ALSO EXPLORED CORRELATIONS BETWEEN DNA METHYLATION AND GENE EXPRESSION USING RNA SEQUENCING DATA FROM THE SAME SAMPLES. TECHNICAL VALIDATION OF RRBS RESULTS WAS PERFORMED USING PYROSEQUENCING. RESULTS: WE IDENTIFIED 79, 56 AND 45 DIFFERENTIALLY METHYLATED REGIONS IN CD4(+) T CELLS, CD8(+) T CELLS AND CD4(-)CD8(-) CELL FRACTIONS, RESPECTIVELY, BETWEEN TYPE 1 DIABETES-SPECIFIC AUTOANTIBODY-POSITIVE INDIVIDUALS AND CONTROL PARTICIPANTS. THE ANALYSIS OF PRE-SEROCONVERSION SAMPLES IDENTIFIED DNA METHYLATION SIGNATURES AT THE VERY EARLY STAGE OF DISEASE, INCLUDING DIFFERENTIAL METHYLATION AT THE PROMOTER OF IRF5 IN CD4(+) T CELLS. FURTHER, WE VALIDATED RRBS RESULTS USING PYROSEQUENCING AT THE FOLLOWING CPG SITES: CHR19:18118304 IN THE PROMOTER OF ARRDC2; CHR21:47307815 IN THE INTRON OF PCBP3; AND CHR14:81128398 IN THE INTERGENIC REGION NEAR TRAF3 IN CD4(+) T CELLS. CONCLUSIONS/INTERPRETATION: THESE PRELIMINARY RESULTS PROVIDE NOVEL INSIGHTS INTO CELL TYPE-SPECIFIC DIFFERENTIAL EPIGENETIC REGULATION OF GENES, WHICH MAY CONTRIBUTE TO TYPE 1 DIABETES PATHOGENESIS AT THE VERY EARLY STAGE OF DISEASE DEVELOPMENT. SHOULD THESE FINDINGS BE VALIDATED, THEY MAY SERVE AS A POTENTIAL SIGNATURE USEFUL FOR DISEASE PREDICTION AND MANAGEMENT. 2022 17 2400 28 EPIGENETIC REPROGRAMMING OF IMMUNE CELLS IN WOMEN WITH PCOS IMPACT GENES CONTROLLING REPRODUCTIVE FUNCTION. CONTEXT: POLYCYSTIC OVARY SYNDROME (PCOS) IS A CHRONIC DISEASE AFFECTING REPRODUCTIVE FUNCTION AND WHOLE-BODY METABOLISM. ALTHOUGH THE ETIOLOGY IS UNCLEAR, EMERGING EVIDENCE INDICATES THAT THE EPIGENETICS MAY BE A CONTRIBUTING FACTOR. OBJECTIVE: TO DETERMINE THE ROLE OF GLOBAL AND GENOME-WIDE EPIGENETIC MODIFICATIONS IN SPECIFIC IMMUNE CELLS IN PCOS COMPARED WITH CONTROLS AND WHETHER THESE COULD BE RELATED TO CLINICAL FEATURES OF PCOS. DESIGN: CROSS-SECTIONAL STUDY. PARTICIPANTS: WOMEN WITH (N = 17) OR WITHOUT PCOS (N = 17). SETTING: RECRUITED FROM THE GENERAL COMMUNITY. MAIN OUTCOME MEASURES: ISOLATED PERIPHERAL BLOOD MONONUCLEAR CELLS WERE ANALYZED USING MULTICOLOR FLOW CYTOMETRY METHODS TO DETERMINE GLOBAL DNA METHYLATION LEVELS IN A CELL-SPECIFIC FASHION. TRANSCRIPTOMIC AND GENOME-WIDE DNA METHYLATION ANALYSES WERE PERFORMED ON T HELPER CELLS USING RNA SEQUENCING AND REDUCED REPRESENTATION BISULFITE SEQUENCING. RESULTS: WOMEN WITH PCOS HAD LOWER GLOBAL DNA METHYLATION IN MONOCYTES (P = 0.006) AND IN T HELPER (P = 0.004), T CYTOTOXIC (P = 0.004), AND B CELLS (P = 0.03). SPECIFIC GENOME-WIDE DNA METHYLATION ANALYSIS OF T HELPER CELLS FROM WOMEN WITH PCOS IDENTIFIED 5581 DIFFERENTIALLY METHYLATED CPG SITES. FUNCTIONAL GENE ONTOLOGY ENRICHMENT ANALYSIS SHOWED THAT GENES LOCATED AT THE PROXIMITY OF DIFFERENTIALLY METHYLATED CPG SITES BELONG TO PATHWAYS RELATED TO REPRODUCTIVE FUNCTION AND IMMUNE CELL FUNCTION. HOWEVER, THESE GENES WERE NOT ALTERED AT THE TRANSCRIPTOMIC LEVEL. CONCLUSIONS: IT WAS SHOWN THAT PCOS IS ASSOCIATED WITH GLOBAL AND GENE-SPECIFIC DNA METHYLATION REMODELING IN A CELL TYPE-SPECIFIC MANNER. FURTHER INVESTIGATION IS WARRANTED TO DETERMINE WHETHER EPIGENETIC REPROGRAMMING OF IMMUNE CELLS IS IMPORTANT IN DETERMINING THE DIFFERENT PHENOTYPES OF PCOS. 2019 18 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 19 274 31 AGE-RELATED CHANGES IN DNA METHYLATION AFFECT RENAL HISTOLOGY AND POST-TRANSPLANT FIBROSIS. DURING AGEING, KIDNEY FUNCTION DECREASES DUE TO RENAL TUBULAR ATROPHY, INTERSTITIAL FIBROSIS, GLOMERULOSCLEROSIS AND ARTERIOSCLEROSIS. RECENTLY, CHANGES IN DNA METHYLATION WERE SHOWN TO CONTRIBUTE TO VARIOUS AGEING PROCESSES. HOWEVER, IT IS UNKNOWN WHETHER SUCH CHANGES ALSO CONTRIBUTE TO AGE-RELATED KIDNEY DYSFUNCTION. TO ASSESS THIS, WE PROFILED GENOME-WIDE CHANGES IN DNA METHYLATION (OVER 800 000 CPG SITES) IN 95 RENAL BIOPSIES OBTAINED PRIOR TO KIDNEY TRANSPLANTATION FROM DONORS AGED 16 TO 73 YEARS. DONOR AGE SIGNIFICANTLY ASSOCIATED WITH THE METHYLATION OF 92 778 CPGS (FALSE DISCOVERY RATE UNDER 0.05), CORRESPONDING TO 10 285 DIFFERENTIALLY METHYLATED REGIONS. THESE REGIONS WERE MOST FREQUENTLY LOCATED IN GENES INVOLVED IN THE WNT/BETA-CATENIN SIGNALING PATHWAY. USING AN INDEPENDENT COHORT OF 67 BIOPSIES, WE AUTONOMOUSLY VALIDATED THESE FINDINGS. INTERESTINGLY, THE METHYLATION STATUS OF THESE 92 778 AGE-RELATED CPGS WAS ASSOCIATED WITH GLOMERULOSCLEROSIS (34.4% OF CPGS AT A FALSE DISCOVERY RATE UNDER 0.05) AND INTERSTITIAL FIBROSIS (0.9%) AND GRAFT FUNCTION AT ONE YEAR AFTER TRANSPLANTATION, BUT NOT WITH TUBULAR ATROPHY AND ARTERIOSCLEROSIS. NO ASSOCIATION WAS OBSERVED WITH ANY OF THESE PATHOLOGIES AT THE TIME OF TRANSPLANTATION (0% AT A FALSE DISCOVERY RATE UNDER 0.05). THUS, AGE-ASSOCIATED CHANGES IN DNA METHYLATION AT THE TIME OF TRANSPLANTATION PREDICT FUTURE INJURY OF TRANSPLANTED KIDNEYS. SPECIFICALLY, OUR EPIGENOME-WIDE ASSOCIATION STUDY DEMONSTRATES THAT EPIGENETIC RENAL AGEING IS IMPLICATED IN PROGRESSIVE FIBROSIS IN BOTH THE GLOMERULUS AND THE INTERSTITIUM. 2019 20 2079 25 EPIGENETIC DNA METHYLATION CHANGES ASSOCIATED WITH HEADACHE CHRONIFICATION: A RETROSPECTIVE CASE-CONTROL STUDY. BACKGROUND THE BIOLOGICAL MECHANISMS OF HEADACHE CHRONIFICATION ARE POORLY UNDERSTOOD. WE AIMED TO IDENTIFY CHANGES IN DNA METHYLATION ASSOCIATED WITH THE TRANSFORMATION FROM EPISODIC TO CHRONIC HEADACHE. METHODS PARTICIPANTS WERE RECRUITED FROM THE POPULATION-BASED NORWEGIAN HUNT STUDY. THIRTY-SIX FEMALE HEADACHE PATIENTS WHO TRANSFORMED FROM EPISODIC TO CHRONIC HEADACHE BETWEEN BASELINE AND FOLLOW-UP 11 YEARS LATER WERE MATCHED AGAINST 35 CONTROLS WITH EPISODIC HEADACHE. DNA METHYLATION WAS QUANTIFIED AT 485,000 CPG SITES, AND CHANGES IN METHYLATION LEVEL AT THESE SITES WERE COMPARED BETWEEN CASES AND CONTROLS BY LINEAR REGRESSION ANALYSIS. DATA WERE ANALYZED IN TWO STAGES (STAGES 1 AND 2) AND IN A COMBINED META-ANALYSIS. RESULTS NONE OF THE TOP 20 CPG SITES IDENTIFIED IN STAGE 1 REPLICATED IN STAGE 2 AFTER MULTIPLE TESTING CORRECTION. IN THE COMBINED META-ANALYSIS THE STRONGEST ASSOCIATED CPG SITES WERE RELATED TO SH2D5 AND NPTX2, TWO BRAIN-EXPRESSED GENES INVOLVED IN THE REGULATION OF SYNAPTIC PLASTICITY. FUNCTIONAL ENRICHMENT ANALYSIS POINTED TO PROCESSES INCLUDING CALCIUM ION BINDING AND ESTROGEN RECEPTOR PATHWAYS. CONCLUSION IN THIS FIRST GENOME-WIDE STUDY OF DNA METHYLATION IN HEADACHE CHRONIFICATION SEVERAL POTENTIALLY IMPLICATED LOCI AND PROCESSES WERE IDENTIFIED. THE STUDY EXEMPLIFIES THE USE OF PROSPECTIVELY COLLECTED POPULATION COHORTS TO SEARCH FOR EPIGENETIC MECHANISMS OF DISEASE. 2018