眼科遺傳學(xué)課件

遺傳學(xué)（Genetics）遺傳學(xué)在醫(yī)學(xué)中的作用闡明疾病的發(fā)病機(jī)制完善病人的診斷和治療預(yù)防或控制疾?。哼z傳篩選遺傳診斷遺傳咨詢產(chǎn)前診斷FocusChromosomeandCellDivisionMolecularGenetics(DNAandGenes)MaintypesofgeneticdisordersMethodsforDNAAnalysisGeneticDiagnosisMolecularGeneticsandOphthalmologyCellDivision有絲分裂（Mitosis）：復(fù)制一次分裂一次

一個細(xì)胞分裂產(chǎn)生兩個在遺傳上與親代完全相同的細(xì)胞的過程減數(shù)分裂（Meiosis）：復(fù)制一次分裂兩次

產(chǎn)生男性和女性配子（精子和卵子）的過程細(xì)胞周期（cellcycle）INTERPHASEG1phase:betweenMphaseandSphaseSphase:DNAduplication,10-12hourG2phase:betweenSphaseandmitosis

Mphase:mitosis,1hour相關(guān)概念同源染色體：homologouschromosomes姊妹染色體；sisterchromosomes等位基因：allele純合：homozygous雜合：heterozygousFocusChromosomeandCellDivisionMolecularGenetics(DNAandGenes)MaintypesofgeneticdisordersMethodsforDNAAnalysisGeneticDiagnosisMolecularGeneticsandOphthalmologyHowGenesWork:DecodingDNAFocusChromosomeandCellDivisionMolecularGenetics(DNAandGenes)MaintypesofgeneticdisordersMethodsforDNAAnalysisGeneticDiagnosisMolecularGeneticsandOphthalmologyMaintypesofgeneticdisordersChromosomaldisorderSinglegenedisorderMultiplegeneormultifactordisorderSomaticcellgeneticdisorderMitochondrialdisorderSinglegenedisorderAutosomalDominantAutosomalRecessiveX-linkedMendelianInheritantlawsLawofSegregation:themembersofeachpairofallelesseparatewhengametesareformedLawofIndependentAssortment:inheritancepatternofonetraitwillnotaffecttheinheritancepatternofanotherAutosomaldominant

遺傳方式是垂直的男女比例相當(dāng)受累個體雙親之一是患者AutosomalRecessive遺傳特征是水平遺傳受累個體僅限于同胞男女發(fā)病比例相同家系中常有近親婚配史X-linked男性患者比例大缺乏男性向男性傳遞FocusChromosomeandCellDivisionMolecularGenetics(DNAandGenes)MaintypesofgeneticdisordersMethodsforDNAAnalysisGeneticDiagnosisMolecularGeneticsandOphthalmologyMethodsforDNAAnalysisPolymerasechainreaction(PCR)GeneMappingandLinkageAnalysisDNAsequencingChain-terminationmethods(Sanger’s)next-generationsequencing

Chain-terminationmethods(Sanger’smethod)FrederickSanger二代測序技術(shù)焦磷酸測序單分子測序DNA芯片測序高通量、平行DiseaseFunctionMapDiseaseGeneGeneMapFunctionFunctionalcloning

PositionalcandidatecloningGeneticLinkageAnalysisRFLPs(restrictionfragmentlengthpolymorphisms)STRs(shorttandemrepeatpolymorphisms):(CA)n,(GA)n,(AA)n,(CG)n,(CAA)n,(GG)nGeneticLinkageAnalysis短串聯(lián)重復(fù)序列（shorttandemrepeats,STR）：又稱為微衛(wèi)星DNA，基本單位是1-8bp的串聯(lián)重復(fù)，重復(fù)單位數(shù)目約15-60個主要形式：（CA）n，（GA）n，（AA）n，（CG）n，（CAA）n，（CGG）n等常選用雜合度較高的微衛(wèi)星標(biāo)記行連鎖分析

GeneticLinkageAnalysis

對于符合孟德爾遺傳規(guī)律的疾病來說，導(dǎo)致家系成員表型的致病基因突變會隨著基因的傳遞從上代傳給下代，而正常人中一般不攜帶該突變，即基因突變與疾病表型呈共分離現(xiàn)象。微衛(wèi)星標(biāo)記行連鎖分析若結(jié)果呈現(xiàn)共分離現(xiàn)象，則說明該家系致病基因位于該標(biāo)記附近，而該標(biāo)記的位置是已知的，故可大致判斷家系中致病基因的位置。Definedascalculationofoddsratio(L)where:

Prob.ofobservedallelicdistributionifmarkerslinkedProb.ofobservedallelicdistributionifnotlinkedExpressedasLODscore(Z)where:

Z=log10LByconvention:LOD>3requiredforlinkage(L>1000:1)LOD<-2sufficienttorejectlinkageL=GeneticLinkageAnalysisCACACACACACACACACACACACACACACACACACACACAPrimer1Primer2

(CA)6(CA)5(CA)4(CA)3(CA)2PrimersflanktheShortTandemRepeats(STR)STRsoccurinpairsandrepeat(i.e.2-6times)DifferencesinsizecanberesolvedbyGelElectrophoresis1,22,31,31,21,21,32,52,32,52,54,5LinkageAnalysis6p116q16MCDR1PBCRASTGD3adMDCORD7RP25D6S257DrusenD6S430D6S313D6S1625D6S2258D6S1613D6S1644D6S249D6S1716D6S475D6S3012.4cM1.2cM5.8cM4.0cM5.8cM3.6cM2.6cMA)GenelocalizedtothisregionvialinkageanalysisB)CreationofoverlappingDNAClonesMarker1(M1)Marker2(M2)C)Identificationofpotentialgenes

M1M2

M1ABCDM2

M1BDM2

M1BM2D)PotentialgeneswithcorrectexpressionpatternE)Identificationofmutationingene連鎖分析結(jié)果微衛(wèi)星標(biāo)記位點(diǎn)D3S23058%變性聚丙烯酰胺凝膠電泳圖（銀染）紅色箭頭所指為家系中的患者，藍(lán)色箭頭所示為可疑重組個體。單基因遺傳病連鎖分析技術(shù)路線收集遺傳性眼病家系臨床特征評估和遺傳特征分析收集靜脈血,DNA提取致病基因的染色體定位致病基因的突變分析外顯子組測序Exome罕見疾病致病基因的確定FocusChromosomeandCellDivisionMolecularGenetics(DNAandGenes)MaintypesofgeneticdisordersMethodsforDNAAnalysisGeneticDiagnosisMolecularGeneticsandOphthalmologyPrenatalDiagnosisUltrasonographyAmniocentesisChorionicVillusSampling(CVS)

chromosomalabnormalitiesenzymopathiessingle-genemutationsMaternalbloodsamplingforfetalbloodcells

Non-invasiveprenatalassessmentoftrisomy21羊膜穿刺術(shù)指征高齡孕婦異常的母體血清三倍體篩查結(jié)果染色體異常家族史神經(jīng)管缺損/異常母體血清甲胎蛋白生化檢查或DNA分析檢測的單基因疾病FocusChromosomeandCellDivisionMolecularGenetics(DNAandGenes)MaintypesofgeneticdisordersMethodsforDNAAnalysisGeneticDiagnosisMolecularGeneticsandOphthalmologyMolecularGeneticsandOphthalmologySinglegene:morethan200geneidentifiedMultilateralgene:AMD,glaucoma,MyopiaMitochondrialdisorder:Leber’shereditaryopticneuropathy(LHON)RetinalDiseaseGenesRetinitispigmentosaDescribedbyDr.Dondersin1875,Nightblindness,constrictionofperipheralvisualfield,Abonespicule–likeappearanceinfundus,SmallornondetectableERG,1/4000。RP---geneticallyheterogeneousAutosomaldominantRP(adRP)AutosomalrecessiveRP(arRP)X-linkedRP(xlRP)DigenicRP(DRP)RP

MappedGeneadRP：

2423arRP：

3933xlRP：

63FunctionofRPgeneFunctionalgroupGenesVisualcascadeRHO,PED6A,PED6B,SAG,CNGA1VisualcycleRPE65,RLBP1,RGR,ABCA4StructuralproteinRDS,ROM1TranscriptionalFactorNRL,CRX,NR2E3ExtracellularproteinCRB1USH2AProteinkinaseMERTK,RP1,PRKCGUnknownfunctionRP2,RPGR,TULP1MultilateralEyeDiseaseAMD,Myopia,GlaucomaRiskfactorAssociationGenome-wideassociation(GWAS)PopulationGeneticsPopulationGeneticsGenefrequencyHardy-Weinbergequilibriump2+2pq+q2=1SingleNucleotidePolymorphisms(SNPs)SNP-geneticmarkerspresentinevery300to1000basesinmanevolutionarilystable--notchangingmuchfromgenerationtogenerationmakingthemeasiertofollowinpopulationstudies.DNA-chipNormalControlsAMDPATIENTSMitochondrialdisorder細(xì)胞質(zhì)線粒體DNA16.5kb,編碼2個rRNA,22tRNA,13多肽基因,氧化磷酸化相關(guān)酶突變率是核DNA的20倍女性傳遞線粒體疾病1871年德國眼科醫(yī)生Leber首先報(bào)告患病率1/30,000--1/50,0001988年，Wallace等首先報(bào)告m.1