Seeonlineversionforlegendandreferences.1144Cell135,December12,2008©2008ElsevierInc.DOI10.1016/j.cell.2008.11.040SnapShot:TheHumanDNAMethylomeinHealthandDiseaseEstebanBallestarandManelEstellerCancerEpigeneticsGroup,SpanishNationalCancerResearchCentre(CNIO),28029Madrid,SpainSnapShot:TheHumanDNAMethylomeinHealthandDiseaseEstebanBallestarandManelEstellerCancerEpigeneticsGroup,SpanishNationalCancerResearchCentre(CNIO),28029Madrid,Spain1144.e1Cell135,December12,2008©2008ElsevierInc.DOI10.1016/j.cell.2008.11.040FigureLegendTheessentialroleofDNAmethylationinXchromosomeinactivationandimprintingiswidelyrecognized,butweknowlittleabouttissue-specificDNAmethylationorDNAmethylationchangesinregulatoryregions.Severalinternationalepigenomeprojects,includingtheHumanEpigenomeProject,plantogeneratedetailedmapsofDNAmethy-lationinnormalcellsandcellsthatarealteredduringdiseasepathogenesis.TheSnapShotshowsasummaryofourcurrentknowledgeoftheDNAmethylationpatternsinnormalhumancellsandinhumancellsindifferentdiseasestates.Innormalcells,DNAmethylationisrestrictedtoafewtissue-specificgenes(whitearrowheads)andimprintedgenes(grayarrowheads)andthroughouttheinactiveX(X1)chromosome(juxtaposedbluelines)infemales.DNAmethylationchangesindiseaseareindicatedbyred(hypermethylation)orgreen(hypomethylation)barsinsidethechromosome;methylationinnormalcellsisindicatedbybluebarsinsidechromosomes.Onlyrepresenta-tiveexamplesofDNAmethylationalterationsincertaindiseasesareshown.Diseasesaremarkedbyarrowheads(cancer,orange;Alzheimer’sdisease,yellow;etc.)andthetypeofDNAmethylationchangeisindicatedbyared(hypermethylation)orgreen(hypomethylation)barinsidethechromosome.Incancercells(orangearrowheads),therearemorethan100genesdocumentedinwhichCpGislandpromoterhypermethylationisassociatedwithtranscriptionalinactivation.TheSnapShotalsoindicatesDNAmethylationchangesassociatedwithgeneticdisorderssuchasα-thalassemiaX-linkedmentalretardationsyndrome(ATRX),facioscapulohumeralmusculardystrophy(FSHD),andimmunodeficiency-centro...
