1 5881 102 SYSTEMATIC INTEGRATED ANALYSIS OF GENETIC AND EPIGENETIC VARIATION IN DIABETIC KIDNEY DISEASE. POOR METABOLIC CONTROL AND HOST GENETIC PREDISPOSITION ARE CRITICAL FOR DIABETIC KIDNEY DISEASE (DKD) DEVELOPMENT. THE EPIGENOME INTEGRATES INFORMATION FROM SEQUENCE VARIATIONS AND METABOLIC ALTERATIONS. HERE, WE PERFORMED A GENOME-WIDE METHYLOME ASSOCIATION ANALYSIS IN 500 SUBJECTS WITH DKD FROM THE CHRONIC RENAL INSUFFICIENCY COHORT FOR DKD PHENOTYPES, INCLUDING GLYCEMIC CONTROL, ALBUMINURIA, KIDNEY FUNCTION, AND KIDNEY FUNCTION DECLINE. WE SHOW DISTINCT METHYLATION PATTERNS ASSOCIATED WITH EACH PHENOTYPE. WE DEFINE METHYLATION VARIATIONS THAT ARE ASSOCIATED WITH UNDERLYING NUCLEOTIDE VARIATIONS (METHYLATION QUANTITATIVE TRAIT LOCI) AND SHOW THAT UNDERLYING GENETIC VARIATIONS ARE IMPORTANT DRIVERS OF METHYLATION CHANGES. WE IMPLEMENTED BAYESIAN MULTITRAIT COLOCALIZATION ANALYSIS (MOLOC) AND SUMMARY DATA-BASED MENDELIAN RANDOMIZATION TO SYSTEMATICALLY ANNOTATE GENOMIC REGIONS THAT SHOW ASSOCIATION WITH KIDNEY FUNCTION, METHYLATION, AND GENE EXPRESSION. WE PRIORITIZED 40 LOCI, WHERE METHYLATION AND GENE-EXPRESSION CHANGES LIKELY MEDIATE THE GENOTYPE EFFECT ON KIDNEY DISEASE DEVELOPMENT. FUNCTIONAL ANNOTATION SUGGESTED THE ROLE OF INFLAMMATION, SPECIFICALLY, APOPTOTIC CELL CLEARANCE AND COMPLEMENT ACTIVATION IN KIDNEY DISEASE DEVELOPMENT. OUR STUDY DEFINES METHYLATION CHANGES ASSOCIATED WITH DKD PHENOTYPES, THE KEY ROLE OF UNDERLYING GENETIC VARIATIONS DRIVING METHYLATION VARIATIONS, AND PRIORITIZES METHYLOME AND GENE-EXPRESSION CHANGES THAT LIKELY MEDIATE THE GENOTYPE EFFECT ON KIDNEY DISEASE PATHOGENESIS. 2020 2 2873 35 FUNCTIONAL METHYLOME ANALYSIS OF HUMAN DIABETIC KIDNEY DISEASE. IN PATIENTS WITH DIABETES MELLITUS, POOR METABOLIC CONTROL HAS A LONG-LASTING IMPACT ON KIDNEY DISEASE DEVELOPMENT. EPIGENETIC CHANGES, INCLUDING CYTOSINE METHYLATION, HAVE BEEN PROPOSED AS POTENTIAL MEDIATORS OF THE LONG-LASTING EFFECT OF ADVERSE METABOLIC EVENTS. OUR UNDERSTANDING OF THE PRESENCE AND CONTRIBUTION OF METHYLATION CHANGES TO DISEASE DEVELOPMENT IS LIMITED BECAUSE OF THE LACK OF COMPREHENSIVE BASE-RESOLUTION METHYLOME INFORMATION OF HUMAN KIDNEY TISSUE SAMPLES AND SITE-SPECIFIC METHYLATION EDITING. BASE RESOLUTION, WHOLE-GENOME BISULFITE SEQUENCING METHYLOME MAPS OF HUMAN DIABETIC KIDNEY DISEASE (DKD) TUBULE SAMPLES, AND ASSOCIATED GENE EXPRESSION MEASURED BY RNA SEQUENCING HIGHLIGHTED WIDESPREAD METHYLATION CHANGES IN DKD. PATHWAY ANALYSIS HIGHLIGHTED COORDINATED (METHYLATION AND GENE EXPRESSION) CHANGES IN IMMUNE SIGNALING, INCLUDING TUMOR NECROSIS FACTOR ALPHA (TNF). CHANGES IN TNF METHYLATION CORRELATED WITH KIDNEY FUNCTION DECLINE. DCAS9-TET1-BASED LOWERING OF THE CYTOSINE METHYLATION LEVEL OF THE TNF DIFFERENTIALLY METHYLATED REGION RESULTED IN AN INCREASE IN THE TNF TRANSCRIPT LEVEL, INDICATING THAT METHYLATION OF THIS LOCUS PLAYS AN IMPORTANT ROLE IN CONTROLLING TNF EXPRESSION. INCREASING THE TNF LEVEL IN DIABETIC MICE INCREASED DISEASE SEVERITY, SUCH AS ALBUMINURIA. IN SUMMARY, OUR RESULTS INDICATE WIDESPREAD METHYLATION DIFFERENCES IN DKD KIDNEYS AND HIGHLIGHTS EPIGENETIC CHANGES IN THE TNF LOCUS AND ITS CONTRIBUTION TO THE DEVELOPMENT OF NEPHROPATHY IN PATIENTS WITH DIABETES MELLITUS. 2019 3 1269 35 CYTOSINE METHYLATION CHANGES IN ENHANCER REGIONS OF CORE PRO-FIBROTIC GENES CHARACTERIZE KIDNEY FIBROSIS DEVELOPMENT. BACKGROUND: ONE IN ELEVEN PEOPLE IS AFFECTED BY CHRONIC KIDNEY DISEASE, A CONDITION CHARACTERIZED BY KIDNEY FIBROSIS AND PROGRESSIVE LOSS OF KIDNEY FUNCTION. EPIDEMIOLOGICAL STUDIES INDICATE THAT ADVERSE INTRAUTERINE AND POSTNATAL ENVIRONMENTS HAVE A LONG-LASTING ROLE IN CHRONIC KIDNEY DISEASE DEVELOPMENT. EPIGENETIC INFORMATION REPRESENTS A PLAUSIBLE CARRIER FOR MEDIATING THIS PROGRAMMING EFFECT. HERE WE DEMONSTRATE THAT GENOME-WIDE CYTOSINE METHYLATION PATTERNS OF HEALTHY AND CHRONIC KIDNEY DISEASE TUBULE SAMPLES OBTAINED FROM PATIENTS SHOW SIGNIFICANT DIFFERENCES. RESULTS: WE IDENTIFY DIFFERENTIALLY METHYLATED REGIONS AND VALIDATE THESE IN A LARGE REPLICATION DATASET. THE DIFFERENTIALLY METHYLATED REGIONS ARE RARELY OBSERVED ON PROMOTERS, BUT MOSTLY OVERLAP WITH PUTATIVE ENHANCER REGIONS, AND THEY ARE ENRICHED IN CONSENSUS BINDING SEQUENCES FOR IMPORTANT RENAL TRANSCRIPTION FACTORS. THIS INDICATES THEIR IMPORTANCE IN GENE EXPRESSION REGULATION. A CORE SET OF GENES THAT ARE KNOWN TO BE RELATED TO KIDNEY FIBROSIS, INCLUDING GENES ENCODING COLLAGENS, SHOW CYTOSINE METHYLATION CHANGES CORRELATING WITH DOWNSTREAM TRANSCRIPT LEVELS. CONCLUSIONS: OUR REPORT RAISES THE POSSIBILITY THAT EPIGENETIC DYSREGULATION PLAYS A ROLE IN CHRONIC KIDNEY DISEASE DEVELOPMENT VIA INFLUENCING CORE PRO-FIBROTIC PATHWAYS AND CAN AID THE DEVELOPMENT OF NOVEL BIOMARKERS AND FUTURE THERAPEUTICS. 2013 4 462 28 ARE ALTERATIONS IN DNA METHYLATION RELATED TO CKD DEVELOPMENT? THE MODIFICATIONS IN GENOMIC DNA METHYLATION ARE INVOLVED IN THE REGULATION OF NORMAL AND PATHOLOGICAL CELLULAR PROCESSES. THE EPIGENETIC REGULATION STIMULATES BIOLOGICAL PLASTICITY AS AN ADAPTIVE RESPONSE TO VARIATIONS IN ENVIRONMENTAL FACTORS. THE ROLE OF EPIGENETIC CHANGES IS VITAL FOR THE DEVELOPMENT OF SOME DISEASES, INCLUDING ATHEROGENESIS, CANCERS, AND CHRONIC KIDNEY DISEASE (CKD). THE RESULTS OF STUDIES PRESENTED IN THIS REVIEW HAVE SUGGESTED THAT ALTERED DNA METHYLATION CAN MODULATE THE EXPRESSION OF PRO-INFLAMMATORY AND PRO-FIBROTIC GENES, AS WELL THOSE ESSENTIAL FOR KIDNEY DEVELOPMENT AND FUNCTION, THUS STIMULATING RENAL DISEASE PROGRESSION. ABNORMALLY INCREASED HOMOCYSTEINE, HYPOXIA, AND INFLAMMATION HAVE BEEN SUGGESTED TO ALTER EPIGENETIC REGULATION OF GENE EXPRESSION IN CKD. STUDIES OF RENAL SAMPLES HAVE DEMONSTRATED THE RELATIONSHIP BETWEEN VARIATIONS IN DNA METHYLATION AND FIBROSIS AND VARIATIONS IN ESTIMATED GLOMERULAR FILTRATION RATE (EGFR) IN HUMAN CKD. THE UNRAVELLING OF THE GENETIC-EPIGENETIC PROFILE WOULD ENHANCE OUR UNDERSTANDING OF PROCESSES UNDERLYING THE DEVELOPMENT OF CKD. THE UNDERSTANDING OF MULTIFACETED RELATIONSHIP BETWEEN DNA METHYLATION, GENES EXPRESSION, AND DISEASE DEVELOPMENT AND PROGRESSION COULD IMPROVE THE ABILITY TO IDENTIFY INDIVIDUALS AT RISK OF CKD AND ENABLE THE CHOICE OF APPROPRIATE DISEASE MANAGEMENT. 2022 5 1583 34 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 6 2483 28 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 7 2982 30 GENETIC CONSIDERATIONS IN PEDIATRIC CHRONIC KIDNEY DISEASE. CHRONIC KIDNEY DISEASE (CKD) IN CHILDREN IS AN IRREVERSIBLE PROCESS THAT, IN SOME CASES, MAY LEAD TO END-STAGE RENAL DISEASE. THE MAJORITY OF CHILDREN WITH CKD HAVE A CONGENITAL DISORDER OF THE KIDNEY OR UROLOGICAL TRACT ARISING FROM BIRTH. THERE IS STRONG EVIDENCE FOR BOTH A GENETIC AND EPIGENETIC COMPONENT TO PROGRESSION OF CKD. UTILIZATION OF GENE-MAPPING STRATEGIES, RANGING FROM GENOME-WIDE ASSOCIATION STUDIES TO SINGLE-NUCLEOTIDE POLYMORPHISM ANALYSIS, SERVES TO IDENTIFY POTENTIAL GENETIC VARIANTS THAT MAY LEND TO DISEASE VARIATION. GENOME-WIDE ASSOCIATION STUDIES EVALUATING POPULATION-BASED DATA HAVE IDENTIFIED DIFFERENT LOCI ASSOCIATED WITH CKD PROGRESSION. ANALYSIS OF SINGLE-NUCLEOTIDE POLYMORPHISMS ON AN INDIVIDUAL LEVEL SUGGESTS THAT SECONDARY SYSTEMIC SEQUELAE OF CKD ARE CLOSELY RELATED TO DYSFUNCTION OF THE CARDIOVASCULAR-INFLAMMATORY AXIS AND MAY LEAD TO ADVANCED CARDIOVASCULAR DISEASE THROUGH ABNORMAL VASCULAR CALCIFICATION AND ACTIVATION OF THE RENIN-ANGIOTENSIN SYSTEM. SIMILARLY, GENETIC VARIANTS AFFECTING CYTOKINE CONTROL, FIBROSIS, AND PARENCHYMAL DEVELOPMENT MAY MODULATE CKD THROUGH DEVELOPMENT AND ACCELERATION OF RENAL INTERSTITIAL FIBROSIS. EPIGENETIC STUDIES EVALUATE MODIFICATION OF THE GENOME THROUGH DNA METHYLATION, HISTONE MODIFICATION, OR RNA INTERFERENCE, WHICH MAY BE DIRECTLY INFLUENCED BY EXTERNAL OR ENVIRONMENTAL FACTORS DIRECTING GENOMIC EXPRESSION. LASTLY, IMPROVED UNDERSTANDING OF THE GENETIC AND EPIGENETIC CONTRIBUTION TO CKD PROGRESSION MAY ALLOW PROVIDERS TO IDENTIFY A POPULATION AT ACCELERATED RISK FOR DISEASE PROGRESSION AND APPLY NOVEL THERAPIES TARGETED AT THE GENETIC MECHANISM OF DISEASE. 2016 8 3 30 "EPIGENOME-WIDE METHYLATION PROFILE OF CHRONIC KIDNEY DISEASE-DERIVED ARTERIAL DNA UNCOVERS NOVEL PATHWAYS IN DISEASE-ASSOCIATED CARDIOVASCULAR PATHOLOGY.". CHRONIC KIDNEY DISEASE (CKD) RELATED CARDIOVASCULAR DISEASE (CVD) IS CHARACTERIZED BY VASCULAR REMODELLING WITH WELL-ESTABLISHED STRUCTURAL AND FUNCTIONAL CHANGES IN THE VASCULAR WALL SUCH AS ARTERIAL STIFFNESS, MATRIX DEPOSITION, AND CALCIFICATION. THESE PHENOTYPIC CHANGES RESEMBLE PATHOLOGY SEEN IN AGEING, AND ARE LIKELY TO BE MEDIATED BY SUSTAINED ALTERATIONS IN GENE EXPRESSION, WHICH MAY BE CAUSED BY EPIGENETIC CHANGES SUCH AS TISSUE-SPECIFIC DNA METHYLATION. WE AIMED TO INVESTIGATE TISSUE SPECIFIC CHANGES IN DNA METHYLATION THAT OCCUR IN CKD-RELATED CVD. GENOME-WIDE DNA METHYLATION CHANGES WERE EXAMINED IN BISULPHITE CONVERTED GENOMIC DNA ISOLATED FROM THE VASCULAR MEDIA OF CKD AND HEALTHY ARTERIES. METHYLATION-SPECIFIC PCR WAS USED TO VALIDATE THE ARRAY DATA, AND THE ASSOCIATION BETWEEN DNA METHYLATION AND GENE AND PROTEIN EXPRESSION WAS EXAMINED. THE DNA METHYLATION AGE WAS COMPARED TO THE CHRONOLOGICAL AGE IN BOTH CASES AND CONTROLS. THREE HUNDRED AND NINETEEN DIFFERENTIALLY METHYLATED REGIONS (DMR) WERE IDENTIFIED SPREAD ACROSS THE GENOME. PATHWAY ANALYSIS REVEALED THAT DMRS ASSOCIATED WITH GENES WERE INVOLVED IN EMBRYONIC AND VASCULAR DEVELOPMENT, AND SIGNALLING PATHWAYS SUCH AS TGFBETA AND FGF. EXPRESSION OF TOP DIFFERENTIALLY METHYLATED GENE HOXA5 SHOWED A SIGNIFICANT NEGATIVE CORRELATION WITH DNA METHYLATION. INTERESTINGLY, DNA METHYLATION AGE AND CHRONOLOGICAL AGE WERE HIGHLY CORRELATED, BUT THERE WAS NO EVIDENCE OF ACCELERATED AGE-RELATED DNA METHYLATION IN THE ARTERIES OF CKD PATIENTS. IN CONCLUSION, WE DEMONSTRATED THAT DIFFERENTIAL DNA METHYLATION IN THE ARTERIAL TISSUE OF CKD PATIENTS REPRESENTS A POTENTIAL MEDIATOR OF ARTERIAL PATHOLOGY AND MAY BE USED TO UNCOVER NOVEL PATHWAYS IN THE GENESIS OF CKD-ASSOCIATED COMPLICATIONS. 2021 9 1604 24 DNA METHYLATION SUSTAINS "INFLAMED" MEMORY OF PERIPHERAL IMMUNE CELLS AGGRAVATING KIDNEY INFLAMMATORY RESPONSE IN CHRONIC KIDNEY DISEASE. THE INCIDENCE OF CHRONIC KIDNEY DISEASE (CKD) HAS RAPIDLY INCREASED IN THE PAST DECADES. A PROGRESSIVE LOSS OF KIDNEY FUNCTION CHARACTERIZES A PART OF CKD EVEN WITH INTENSIVE SUPPORTIVE TREATMENT. IRRESPECTIVE OF ITS ETIOLOGY, CKD PROGRESSION IS GENERALLY ACCOMPANIED WITH THE DEVELOPMENT OF CHRONIC KIDNEY INFLAMMATION THAT IS PATHOLOGICALLY FEATURED BY THE LOW-GRADE BUT CHRONIC ACTIVATION OF RECRUITED IMMUNE CELLS. CUMULATIVE EVIDENCE SUPPORT THAT ABERRANT DNA METHYLATION PATTERN OF DIVERSE PERIPHERAL IMMUNE CELLS, INCLUDING T CELLS AND MONOCYTES, IS CLOSELY ASSOCIATED WITH CKD DEVELOPMENT IN MANY CHRONIC DISEASE SETTINGS. THE CHANGE OF DNA METHYLATION PROFILE CAN SUSTAIN FOR A LONG TIME AND AFFECT THE FUTURE GENES EXPRESSION IN THE CIRCULATING IMMUNE CELLS EVEN AFTER THEY MIGRATE FROM THE CIRCULATION INTO THE INVOLVED KIDNEY. IT IS OF CLINICAL INTEREST TO REVEAL THE UNDERLYING MECHANISM OF HOW ALTERED DNA METHYLATION REGULATES THE INTENSITY AND THE TIME LENGTH OF THE INFLAMMATORY RESPONSE IN THE RECRUITED EFFECTOR CELLS. WE AND OTHERS RECENTLY DEMONSTRATED THAT ALTERED DNA METHYLATION OCCURS IN PERIPHERAL IMMUNE CELLS AND PROFOUNDLY CONTRIBUTES TO CKD DEVELOPMENT IN SYSTEMIC CHRONIC DISEASES, SUCH AS DIABETES AND HYPERTENSION. THIS REVIEW WILL SUMMARIZE THE CURRENT FINDINGS ABOUT THE INFLUENCE OF ABERRANT DNA METHYLATION ON CIRCULATING IMMUNE CELLS AND HOW IT POTENTIALLY DETERMINES THE OUTCOME OF CKD. 2021 10 6013 30 THE APPLICATIONS OF DNA METHYLATION AS A BIOMARKER IN KIDNEY TRANSPLANTATION: A SYSTEMATIC REVIEW. BACKGROUND: ALTHOUGH KIDNEY TRANSPLANTATION IMPROVES PATIENT SURVIVAL AND QUALITY OF LIFE, LONG-TERM RESULTS ARE HAMPERED BY BOTH IMMUNE- AND NON-IMMUNE-MEDIATED COMPLICATIONS. CURRENT BIOMARKERS OF POST-TRANSPLANT COMPLICATIONS, SUCH AS ALLOGRAFT REJECTION, CHRONIC RENAL ALLOGRAFT DYSFUNCTION, AND CUTANEOUS SQUAMOUS CELL CARCINOMA, HAVE A SUBOPTIMAL PREDICTIVE VALUE. DNA METHYLATION IS AN EPIGENETIC MODIFICATION THAT DIRECTLY AFFECTS GENE EXPRESSION AND PLAYS AN IMPORTANT ROLE IN PROCESSES SUCH AS ISCHEMIA/REPERFUSION INJURY, FIBROSIS, AND ALLOREACTIVE IMMUNE RESPONSE. NOVEL TECHNIQUES CAN QUICKLY ASSESS THE DNA METHYLATION STATUS OF MULTIPLE LOCI IN DIFFERENT CELL TYPES, ALLOWING A DEEP AND INTERESTING STUDY OF CELLS' ACTIVITY AND FUNCTION. THEREFORE, DNA METHYLATION HAS THE POTENTIAL TO BECOME AN IMPORTANT BIOMARKER FOR PREDICTION AND MONITORING IN KIDNEY TRANSPLANTATION. PURPOSE OF THE STUDY: THE AIM OF THIS STUDY WAS TO EVALUATE THE ROLE OF DNA METHYLATION AS A POTENTIAL BIOMARKER OF GRAFT SURVIVAL AND COMPLICATIONS DEVELOPMENT IN KIDNEY TRANSPLANTATION. MATERIAL AND METHODS: A SYSTEMATIC REVIEW OF SEVERAL DATABASES HAS BEEN CONDUCTED. THE NEWCASTLE-OTTAWA SCALE AND THE JADAD SCALE HAVE BEEN USED TO ASSESS THE RISK OF BIAS FOR OBSERVATIONAL AND RANDOMIZED STUDIES, RESPECTIVELY. RESULTS: TWENTY ARTICLES REPORTING ON DNA METHYLATION AS A BIOMARKER FOR KIDNEY TRANSPLANTATION WERE INCLUDED, ALL USING DNA METHYLATION FOR PREDICTION AND MONITORING. DNA METHYLATION PATTERN ALTERATIONS IN CELLS ISOLATED FROM DIFFERENT TISSUES, SUCH AS KIDNEY BIOPSIES, URINE, AND BLOOD, HAVE BEEN ASSOCIATED WITH ISCHEMIA-REPERFUSION INJURY AND CHRONIC RENAL ALLOGRAFT DYSFUNCTION. THESE ALTERATIONS OCCURRED IN DIFFERENT AND SPECIFIC LOCI. DNA METHYLATION STATUS HAS ALSO PROVED TO BE IMPORTANT FOR IMMUNE RESPONSE MODULATION, HAVING A CRUCIAL ROLE IN REGULATORY T CELL DEFINITION AND ACTIVITY. RESEARCH ALSO FOCUSED ON A BETTER UNDERSTANDING OF THE ROLE OF THIS EPIGENETIC MODIFICATION ASSESSMENT FOR REGULATORY T CELLS ISOLATION AND EXPANSION FOR FUTURE TOLERANCE INDUCTION-ORIENTED THERAPIES. CONCLUSIONS: STUDIES INCLUDED IN THIS REVIEW ARE HETEROGENEOUS IN STUDY DESIGN, BIOLOGICAL SAMPLES, AND OUTCOME. MORE COORDINATED INVESTIGATIONS ARE NEEDED TO AFFIRM DNA METHYLATION AS A CLINICALLY RELEVANT BIOMARKER IMPORTANT FOR PREVENTION, MONITORING, AND INTERVENTION. 2022 11 2920 32 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 12 1518 26 DNA METHYLATION AS AN EPIGENETIC MECHANISM IN THE DEVELOPMENT OF MULTIPLE SCLEROSIS. THE EPIGENETIC MECHANISMS OF GENE EXPRESSION REGULATION ARE A GROUP OF THE KEY CELLULAR AND MOLECULAR PATHWAYS THAT LEAD TO INHERITED ALTERATIONS IN GENES' ACTIVITY WITHOUT CHANGING THEIR CODING SEQUENCE. DNA METHYLATION AT THE C5 POSITION OF CYTOSINE IN CPG DINUCLEOTIDES IS AMONGST THE CENTRAL EPIGENETIC MECHANISMS. CURRENTLY, THE NUMBER OF STUDIES THAT ARE DEVOTED TO THE IDENTIFICATION OF METHYLATION PATTERNS SPECIFIC TO MULTIPLE SCLEROSIS (MS), A SEVERE CHRONIC AUTOIMMUNE DISEASE OF THE CENTRAL NERVOUS SYSTEM, IS ON A RAPID RISE. HOWEVER, THE ISSUE OF THE CONTRIBUTION OF DNA METHYLATION TO THE DEVELOPMENT OF THE DIFFERENT CLINICAL PHENOTYPES OF THIS HIGHLY HETEROGENEOUS DISEASE HAS ONLY BEGUN TO ATTRACT THE ATTENTION OF RESEARCHERS. THIS REVIEW SUMMARIZES THE DATA ON THE MOLECULAR MECHANISMS UNDERLYING DNA METHYLATION AND THE MS RISK FACTORS THAT CAN AFFECT THE DNA METHYLATION PROFILE AND, THEREBY, MODULATE THE EXPRESSION OF THE GENES INVOLVED IN THE DISEASE'S PATHOGENESIS. THE FOCUS OF OUR ATTENTION IS CENTERED ON THE ANALYSIS OF THE PUBLISHED DATA ON THE DIFFERENTIAL METHYLATION OF DNA FROM VARIOUS BIOLOGICAL SAMPLES OF MS PATIENTS OBTAINED USING BOTH THE CANDIDATE GENE APPROACH AND HIGH-THROUGHPUT METHODS. 2021 13 4228 14 METHYLATION OF INFLAMMATORY CELLS IN LUNG DISEASES. THIS CHAPTER OVERVIEWS ROLES OF DNA METHYLATION IN INFLAMMATORY CELL BIOLOGY WITH THE FOCUSES ON LYMPHOCYTES AND MACROPHAGES/MONOCYTES IN LUNG DISEASES, ALTHOUGH THE MOLECULAR MECHANISMS BY WHICH TARGET GENES ARE METHYLATED AND REGULATED IN LUNG DISEASES REMAIN UNCLEAR. MOST OF EPIGENETIC STUDIES ON DNA METHYLATION OF TARGET GENES IN LUNG DISEASES MAINLY DEMONSTRATED THE CORRELATION OF DNA METHYLATION OF TARGET GENES WITH THE LEVELS OF OTHER CORRESPONDING FACTORS, WITH THE SPECIFICITY OF CLINICAL PHENOMES, AND WITH THE SEVERITY OF LUNG DISEASES. THERE IS AN URGENT NEED TO IDENTIFY AND VALIDATE THE SPECIFICITY AND REGULATORY MECHANISMS OF INFLAMMATORY CELL EPIGENETICS IN DEPTH. THE EPIGENETIC HETEROGENEITY AMONG DIFFERENT SUBSETS OF T CELLS AND AMONG PROMOTERS OR NON-PROMOTERS OF TARGET GENES SHOULD BE FURTHERMORE CLARIFIED IN ACUTE OR CHRONIC LUNG DISEASES AND CANCERS. THE HYPER/HYPO-METHYLATION AND MODIFICATIONS OF CHROMOSOL AND EXTRACHROMOSOMAL DNA MAY RESULT IN ALTERNATIONS IN PROTEINS WITHIN INFLAMMATORY CELLS, WHICH CAN BE IDENTIFIED AS DISEASE-SPECIFIC BIOMARKERS AND THERAPEUTIC TARGETS. 2020 14 857 28 CHROMATIN ARCHITECTURE REVEALS CELL TYPE-SPECIFIC TARGET GENES FOR KIDNEY DISEASE RISK VARIANTS. BACKGROUND: CELL TYPE-SPECIFIC TRANSCRIPTIONAL PROGRAMMING RESULTS FROM THE COMBINATORIAL INTERPLAY BETWEEN THE REPERTOIRE OF ACTIVE REGULATORY ELEMENTS. DISEASE-ASSOCIATED VARIANTS DISRUPT SUCH PROGRAMMING, LEADING TO ALTERED EXPRESSION OF DOWNSTREAM REGULATED GENES AND THE ONSET OF PATHOLOGICAL STATES. HOWEVER, DUE TO THE NON-LINEAR REGULATORY PROPERTIES OF NON-CODING ELEMENTS SUCH AS ENHANCERS, WHICH CAN ACTIVATE TRANSCRIPTION AT LONG DISTANCES AND IN A NON-DIRECTIONAL WAY, THE IDENTIFICATION OF CAUSAL VARIANTS AND THEIR TARGET GENES REMAINS CHALLENGING. HERE, WE PROVIDE A MULTI-OMICS ANALYSIS TO IDENTIFY REGULATORY ELEMENTS ASSOCIATED WITH FUNCTIONAL KIDNEY DISEASE VARIANTS, AND DOWNSTREAM REGULATED GENES. RESULTS: IN ORDER TO UNDERSTAND THE GENETIC RISK OF KIDNEY DISEASES, WE GENERATED A COMPREHENSIVE DATASET OF THE CHROMATIN LANDSCAPE OF HUMAN KIDNEY TUBULE CELLS, INCLUDING TRANSCRIPTION-CENTERED 3D CHROMATIN ORGANIZATION, HISTONE MODIFICATIONS DISTRIBUTION AND TRANSCRIPTOME WITH HICHIP, CHIP-SEQ AND RNA-SEQ. WE IDENTIFIED GENOME-WIDE FUNCTIONAL ELEMENTS AND THOUSANDS OF INTERACTIONS BETWEEN THE DISTAL ELEMENTS AND TARGET GENES. THE RESULTS REVEALED THAT RISK VARIANTS FOR RENAL TUMOR AND CHRONIC KIDNEY DISEASE WERE ENRICHED IN KIDNEY TUBULE CELLS. WE FURTHER PINPOINTED THE TARGET GENES FOR THE VARIANTS AND VALIDATED TWO TARGET GENES BY CRISPR/CAS9 GENOME EDITING TECHNIQUES IN ZEBRAFISH, DEMONSTRATING THAT SLC34A1 AND MTX1 WERE INDISPENSABLE GENES TO MAINTAIN KIDNEY FUNCTION. CONCLUSIONS: OUR RESULTS PROVIDE A VALUABLE MULTI-OMICS RESOURCE ON THE CHROMATIN LANDSCAPE OF HUMAN KIDNEY TUBULE CELLS AND ESTABLISH A BIOINFORMATIC PIPELINE IN DISSECTING FUNCTIONS OF KIDNEY DISEASE-ASSOCIATED VARIANTS BASED ON CELL TYPE-SPECIFIC EPIGENOME. 2021 15 287 27 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 16 1508 35 DNA METHYLATION AND MRNA AND MICRORNA EXPRESSION OF SLE CD4+ T CELLS CORRELATE WITH DISEASE PHENOTYPE. SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) IS AN AUTOIMMUNE DISEASE WELL KNOWN FOR ITS CLINICAL HETEROGENEITY, AND ITS ETIOLOGY SECONDARY TO A CROSS-TALK INVOLVING GENETIC PREDISPOSITION AND ENVIRONMENTAL STIMULI. ALTHOUGH GENOME-WIDE ANALYSIS HAS CONTRIBUTED GREATLY TO OUR UNDERSTANDING OF THE GENETIC BASIS OF SLE, THERE IS INCREASING EVIDENCE FOR A ROLE OF EPIGENETICS. INDEED, RECENT DATA HAVE DEMONSTRATED THAT IN PATIENTS WITH SLE, THERE ARE STRIKING ALTERATIONS OF DNA METHYLATION, HISTONE MODIFICATIONS, AND DEREGULATED MICRORNA EXPRESSION, THE SUM OF WHICH CONTRIBUTE TO OVER-EXPRESSION OF SELECT AUTOIMMUNE-RELATED GENES AND LOSS OF TOLERANCE. TO ADDRESS THIS ISSUE AT THE LEVEL OF CLINICAL PHENOTYPE, WE PERFORMED DNA METHYLATION, MRNA AND MICRORNA EXPRESSION SCREENING USING HIGH-THROUGHPUT SEQUENCING OF PURIFIED CD4+ T CELLS FROM PATIENTS WITH SLE, COMPARED TO AGE AND SEX MATCHED CONTROLS. IN PARTICULAR, WE STUDIED 42 PATIENTS WITH SLE AND DIVIDED THIS GROUP INTO THREE CLINICAL PHENOTYPES: A) THE PRESENCE OF SKIN LESIONS WITHOUT SIGNS OF SYSTEMIC PATHOLOGY; B) SKIN LESIONS BUT ALSO CHRONIC RENAL PATHOLOGY; AND C) SKIN LESIONS, CHRONIC RENAL PATHOLOGY AND POLYARTICULAR DISEASE. INTERESTINGLY, AND AS EXPECTED, SEQUENCING DATA REVEALED CHANGES IN DNA METHYLATION IN SLE COMPARED TO CONTROLS. HOWEVER, AND MORE IMPORTANTLY, ALTHOUGH THERE WERE COMMON METHYLATION CHANGES FOUND IN ALL GROUPS OF SLE COMPARED TO CONTROLS, THERE WAS SPECIFIC DNA METHYLATION CHANGES THAT CORRELATED WITH CLINICAL PHENOTYPE. THESE INCLUDED CHANGES IN THE NOVEL KEY TARGET GENES NLRP2, CD300LB AND S1PR3, AS WELL AS CHANGES IN THE CRITICAL PATHWAYS, INCLUDING THE ADHERENS JUNCTION AND LEUKOCYTE TRANSENDOTHELIAL MIGRATION. WE ALSO NOTED THAT A SIGNIFICANT PROPORTION OF GENES UNDERGOING DNA METHYLATION CHANGES WERE INVERSELY CORRELATED WITH GENE EXPRESSION AND THAT MIRNA SCREENING REVEALED THE EXISTENCE OF SUBSETS WITH CHANGES IN EXPRESSION. INTEGRATED ANALYSIS OF THIS DATA HIGHLIGHTS SPECIFIC SETS OF MIRNAS CONTROLLED BY DNA METHYLATION, AND GENES THAT ARE ALTERED BY METHYLATION AND TARGETED BY MIRNAS. IN CONCLUSION, OUR FINDINGS SUGGEST SELECT EPIGENETIC MECHANISMS THAT CONTRIBUTE TO CLINICAL PHENOTYPES AND FURTHER SHED LIGHT ON A NEW VENUE FOR BASIC SLE RESEARCH. 2014 17 1014 24 CIGARETTE SMOKING AND DNA METHYLATION. DNA METHYLATION IS THE MOST STUDIED EPIGENETIC MODIFICATION, CAPABLE OF CONTROLLING GENE EXPRESSION IN THE CONTEXTS OF NORMAL TRAITS OR DISEASES. IT IS HIGHLY DYNAMIC DURING EARLY EMBRYOGENESIS AND REMAINS RELATIVELY STABLE THROUGHOUT LIFE, AND SUCH PATTERNS ARE INTRICATELY RELATED TO HUMAN DEVELOPMENT. DNA METHYLATION IS A QUANTITATIVE TRAIT DETERMINED BY A COMPLEX INTERPLAY OF GENETIC AND ENVIRONMENTAL FACTORS. GENETIC VARIANTS AT A SPECIFIC LOCUS CAN INFLUENCE BOTH REGIONAL AND DISTANT DNA METHYLATION. THE ENVIRONMENT CAN HAVE VARYING EFFECTS ON DNA METHYLATION DEPENDING ON WHEN THE EXPOSURE OCCURS, SUCH AS DURING PRENATAL LIFE OR DURING ADULTHOOD. IN PARTICULAR, CIGARETTE SMOKING IN THE CONTEXT OF BOTH CURRENT SMOKING AND PRENATAL EXPOSURE IS A STRONG MODIFIER OF DNA METHYLATION. EPIGENOME-WIDE ASSOCIATION STUDIES HAVE UNCOVERED CANDIDATE GENES ASSOCIATED WITH CIGARETTE SMOKING THAT HAVE BIOLOGICALLY RELEVANT FUNCTIONS IN THE ETIOLOGY OF SMOKING-RELATED DISEASES. AS SUCH, DNA METHYLATION IS A POTENTIAL MECHANISTIC LINK BETWEEN CURRENT SMOKING AND CANCER, AS WELL AS PRENATAL CIGARETTE-SMOKE EXPOSURE AND THE DEVELOPMENT OF ADULT CHRONIC DISEASES. 2013 18 4531 31 MULTILAYER-OMICS ANALYSES OF HUMAN CANCERS: EXPLORATION OF BIOMARKERS AND DRUG TARGETS BASED ON THE ACTIVITIES OF THE INTERNATIONAL HUMAN EPIGENOME CONSORTIUM. EPIGENETIC ALTERATIONS CONSISTING MAINLY OF DNA METHYLATION ALTERATIONS AND HISTONE MODIFICATION ALTERATIONS ARE FREQUENTLY OBSERVED IN CANCERS ASSOCIATED WITH CHRONIC INFLAMMATION AND/OR PERSISTENT INFECTION WITH VIRUSES OR OTHER PATHOGENIC MICROORGANISMS, OR WITH CIGARETTE SMOKING. ACCUMULATING EVIDENCE SUGGESTS THAT ALTERATIONS OF DNA METHYLATION ARE INVOLVED EVEN IN THE EARLY AND PRECANCEROUS STAGES. ON THE OTHER HAND, IN PATIENTS WITH CANCERS, ABERRANT DNA METHYLATION IS FREQUENTLY ASSOCIATED WITH TUMOR AGGRESSIVENESS AND POOR PATIENT OUTCOME. RECENTLY, EPIGENOME ALTERATIONS HAVE BEEN ATTRACTING A GREAT DEAL OF ATTENTION FROM RESEARCHERS WHO ARE FOCUSING ON NOT ONLY CANCERS BUT ALSO NEURONAL, IMMUNE AND METABOLIC DISORDERS. IN ORDER TO ACCURATELY IDENTIFY DISEASE-SPECIFIC EPIGENOME PROFILES THAT COULD BE POTENTIALLY APPLICABLE FOR DISEASE PREVENTION, DIAGNOSIS AND THERAPY, STRICT COMPARISON WITH STANDARD EPIGENOME PROFILES OF NORMAL TISSUES IS INDISPENSABLE. HOWEVER, EPIGENOME MECHANISMS SHOW HETEROGENEITY AMONG TISSUES AND CELL LINEAGES. THEREFORE, IT IS NOT EASY TO OBTAIN A COMPREHENSIVE PICTURE OF STANDARD EPIGENOME PROFILES OF NORMAL TISSUES. IN 2010, THE INTERNATIONAL HUMAN EPIGENOME CONSORTIUM (IHEC) WAS ESTABLISHED TO COORDINATE THE PRODUCTION OF REFERENCE MAPS OF HUMAN EPIGENOMES FOR KEY CELLULAR STATES. IN ORDER TO GAIN SUBSTANTIAL COVERAGE OF THE HUMAN EPIGENOME, THE IHEC HAS SET AN AMBITIOUS GOAL TO DECIPHER AT LEAST 1000 EPIGENOMES WITHIN THE NEXT 7-10 YEARS. WE CONSIDER THAT PATHWAY ANALYSIS USING GENES SHOWING MULTILAYER-OMICS ABNORMALITIES, INCLUDING GENOME, EPIGENOME, TRANSCRIPTOME, PROTEOME AND METABOLOME ABNORMALITIES, MAY BE USEFUL FOR ELUCIDATING THE MOLECULAR BACKGROUND OF PATHOGENESIS AND FOR EXPLORING POSSIBLE THERAPEUTIC TARGETS FOR EACH DISEASE. 2014 19 1474 31 DISTINCT PATTERNS OF TRANSCRIPTIONAL AND EPIGENETIC ALTERATIONS CHARACTERIZE ACUTE AND CHRONIC KIDNEY INJURY. ACUTE KIDNEY INJURY (AKI) AND CHRONIC KIDNEY DISEASE (CKD) ARE CONSIDERED EARLY AND LATE PHASES OF A PATHOLOGIC CONTINUUM OF INTERCONNECTED DISEASE STATES. ALTHOUGH CHANGES IN GENE EXPRESSION PATTERNS HAVE RECENTLY BEEN ELUCIDATED FOR THE TRANSITION OF AKI TO CKD, THE EPIGENETIC REGULATION OF KEY KIDNEY INJURY RELATED GENES REMAINS POORLY UNDERSTOOD. WE USED MULTIPLEX RT-QPCR, CHIP-QPCR AND INTEGRATIVE ANALYSIS TO COMPARE TRANSCRIPTIONAL AND EPIGENETIC CHANGES AT RENAL DISEASE-ASSOCIATED GENES ACROSS MOUSE AKI AND CKD MODELS. THESE STUDIES SHOWED THAT: (I) THERE ARE SUBSETS OF GENES WITH DISTINCT TRANSCRIPTIONAL AND EPIGENETICALLY PROFILES SHARED BY AKI AND CKD BUT ALSO SUBSETS THAT ARE SPECIFIC TO EITHER THE EARLY OR LATE STAGES OF RENAL INJURY; (II) DIFFERENCES IN EXPRESSION OF A SMALL NUMBER OF GENES IS SUFFICIENT TO DISTINGUISH AKI FROM CKD; (III) TRANSCRIPTION PLAYS A KEY ROLE IN THE UPREGULATION OF BOTH AKI AND CKD GENES WHILE POST-TRANSCRIPTIONAL REGULATION APPEARS TO PLAY A MORE SIGNIFICANT ROLE IN DECREASED EXPRESSION OF BOTH AKI AND CKD GENES; AND (IV) SUBSETS OF TRANSCRIPTIONALLY UPREGULATED GENES SHARE EPIGENETIC SIMILARITIES WHILE DOWNREGULATED GENES DO NOT. COLLECTIVELY, OUR STUDY SUGGESTS THAT IDENTIFIED COMMON TRANSCRIPTIONAL AND EPIGENETIC PROFILES OF KIDNEY INJURY LOCI COULD BE EXPLOITED FOR THERAPEUTIC TARGETING IN AKI AND CKD. 2018 20 2972 29 GENETIC AND EPIGENETIC STUDIES IN DIABETIC KIDNEY DISEASE. CHRONIC KIDNEY DISEASE IS A WORLDWIDE HEALTH CRISIS, WHILE DIABETIC KIDNEY DISEASE (DKD) HAS BECOME THE LEADING CAUSE OF END-STAGE RENAL DISEASE (ESRD). DKD IS A MICROVASCULAR COMPLICATION AND OCCURS IN 30-40% OF DIABETES PATIENTS. EPIDEMIOLOGICAL INVESTIGATIONS AND CLINICAL OBSERVATIONS ON THE FAMILIAL CLUSTERING AND HERITABILITY IN DKD HAVE HIGHLIGHTED AN UNDERLYING GENETIC SUSCEPTIBILITY. FURTHERMORE, DKD IS A PROGRESSIVE AND LONG-TERM DIABETIC COMPLICATION, IN WHICH EPIGENETIC EFFECTS AND ENVIRONMENTAL FACTORS INTERACT WITH AN INDIVIDUAL'S GENETIC BACKGROUND. IN RECENT YEARS, RESEARCHERS HAVE UNDERTAKEN GENETIC AND EPIGENETIC STUDIES OF DKD IN ORDER TO BETTER UNDERSTAND ITS MOLECULAR MECHANISMS. IN THIS REVIEW, CLINICAL MATERIAL, RESEARCH APPROACHES AND EXPERIMENTAL DESIGNS THAT HAVE BEEN USED FOR GENETIC AND EPIGENETIC STUDIES OF DKD ARE DESCRIBED. CURRENT INFORMATION FROM GENETIC AND EPIGENETIC STUDIES OF DKD AND ESRD IN PATIENTS WITH DIABETES, INCLUDING THE APPROACHES OF GENOME-WIDE ASSOCIATION STUDY (GWAS) OR EPIGENOME-WIDE ASSOCIATION STUDY (EWAS) AND CANDIDATE GENE ASSOCIATION ANALYSES, ARE SUMMARIZED. FURTHER INVESTIGATION OF MOLECULAR DEFECTS IN DKD WITH NEW APPROACHES SUCH AS NEXT GENERATION SEQUENCING ANALYSIS AND PHENOME-WIDE ASSOCIATION STUDY (PHEWAS) IS ALSO DISCUSSED. 2019