医学遗传学 遗传病的诊断

遗传病的诊断

1第一节临床诊断依据患者的表型，并结合家系分析，判定是否患有某种遗传病，并确定遗传方式和遗传规律2第二节遗传学诊断通过检测遗传物质、蛋白产物和代谢产物的异常类型，对遗传性疾病进行诊断。依诊断方法分为：细胞遗传学和分子遗传学诊断依据临床目的分为：诊断性检测，症状前检测，携带者检测和产前检测依不同的遗传病分为：染色体病诊断、基因组病诊断和单基因病诊断3Typesofgeneticabnormality

遗传异常类型ThreelevelsGenomemutationChromosomemutationGenemutation4GenomeMutation

基因组突变AbnormalitiesofChromosomenumber（染色体数量异常）Heteroploid:chromosomenumberotherthan46Euploidy（整倍体）–achromosomenumberthatisamultipleofthenormalhaploidset染色体数目是正常单倍体的多倍(2n,3n,4n):92,XXXXor92,XXYYAneuploidy（非整倍体）

Monosomy–havingonlyonememberofahomologouspair:Turnersyndrome(45,X;45,XY,-22)Trisomy–havingthreecopiesofasinglechromosome:(47,XX,+21;47,XY,+18and47,XY,+13)5Chromosomemutation

染色体突变AbnormalitiesofChromosomestructureUnbalancedrearrangementDeletions/DuplicationsMarker/RingChromosomeIsochromosomeBalancedrearrangementTranslocationsRobertsoniantranslocationInsertionsInversions6Incidenceofchromosomeabnormalitiesinnewborn/染色体异常发生率7GeneMutation基因突变Abnormalitiesofindividualgene8ApproachesofTests-Cytogenetics(细胞遗传学）ConventionalCytogeneticsKaryotype（核型)MolecularCytogeneticsFluorescenceinsituHybridization(FISH)Chromosomalmicroarrayanalysis(CMA)orCytogenomicmicroarray-MolecularGenetics(分子遗传学）PCRSequencing9Banding>5-10MbFISH>150kbaCGH>5-10KbSequencing>1bp10ChromosomesphotographedduringmetaphaseorprometaphaseandarrangedinastandardsequenceG-banding(G显带）Standard550bands(5-10Mb)HighResolution850bands(2-3Mb)WholegenomelevelofChromosomenumberandstructurevariationsKaryotyping（核型分析）Metaphase,prometaphase,prophase

KaryotypeBandingpatternsareimportantforidentificationofchromosomesinkaryotypeanalysis（显色带在核型分析的染色体鉴别中是非常重要的）

中间着丝粒近中间着丝粒近端着丝粒12Triploidy三倍体(69,XXX)

1/900livebirths（出生率）Leadingcauseofmentalretardationandheartdefects（智力障碍和心脏缺陷）Wideflatskulls,面宽平40%congenitalheartdefects先天性心脏病Trisomy21:

DownSyndrome(47,XX,+21)

14Trisomy13:

PatauSyndrome(47,XY,+13)

1/15,000birthsLethal;meansurvivaltime1monthFacialmalformations,eyedefects,extrafingersortoes,andlargeprotrudingheelsSeveremalformationsofbrain,nervoussystem,andheartParentalageonlyknownriskfactor

15Trisomy18:

EdwardsSyndrome(47,+18)1/11,000birthsAveragesurvivaltime2–4monthsAffectedinfantssmallatbirthgrowslowlyandarementallyretardedMalformationofheart,hands,andfeetForunknownreasons80%ofalltrisomy18arefemaleAdvancedmaternalageisariskfactor16TurnerandKlinefelterSyndromes45,X1/10,000birthsFemales;short,widechest;wideneck;rudimentaryovariesandabnormalsexualdevelopmentNomentaldysfunction47,XXY1/1000Featuresdonotdevelopuntilafterpuberty青春期后显现症状malewithlowfertilityandmentaldysfunction17Chromosomestructurevariations

（染色体结构变异）

FluorescenceInSituHybridization(FISH)Detectaspecificgenomicregion(Notforwhole)ProbeswithfluorescentmoleculeslabellingProbeusingindividualchromosomesorportionsofchromosomes:detectionofexistenceofanabnormalchromosomeRepetitiveDNAprobes:detectionofthenumberofcopiesofaparticularchromosomeIdentifieschromosomalabnormalities(>150kb)19ApplicationsMappingMicro-deletionCountTranslocation204p16.3Wolf-Hirschhorn5p15.2Cri-du-Chat7q11.23Williams13q14.2Retinoblastoma15q11.2AngelmanPraderWilli17p13.3MillerDieker17p11.2SmithMagenis22q11.21DiGeorge/VCFS22q13.3DeletionSyndromeXp22.31STSKallmanYp11.3SRY1p36Monosomy1p36TargetedFISHTests

microdelsubtelpseudoauto6211MicroarraysProbeplacementFluorescentdyelabellingControlSamplesTestsamplesArraytechnologyistheplacementofaseriesofDNA/RNAprobesonaglassslideandhybridizationwithgenomicmaterialfromapatientofinterest.

Expressionarrays,whichareRNA-based,lookfortheexpressionofaseriesofgenes,andareoftenusedincancerprofiling;Molecularprobeinversionarrays,whichcanbeusedtolookformutationsinaseriesofgenesofinterest;Genomicarrays,whichlookforlargerchanges(lossorgain)inapatient'sDNA.Bacterialartificialchromosome(BAC):100-200KbBACwhichmaycontainrepetitivesequences,lowerresolution,higherbackgroundandlessconsistent.Oligonucleotidearrays:25-60meruniquesequences,customdesigned,lowbackgroundandconsistentperformance,mostpopular.Singlenucleotidepolymorphism(SNP)andoligarrays.detectbothgenomicCNVsplusUPD,LOH,andexcessivehomozygosity(suchasconsanguinity).Typesofarrays231241Microarraydesign–customizedandcomputerized251toidentifygenomiccopynumbervariations(CNVs)Comparativegenomichybridizationarray(aCGH)(<100kb)Singlenucleotidepolymorphismarray(SNP)(5~10kb)Chromosomalmicroarrayanalysis(CMA)orCytogenomicmicroarray（染色体微阵列分析）261aCGHComparativegenomichybridizationarray271128RepresentativeaCGHResultEach60meroligonucleotideprobeisrepresentedbyadotLog2ratio(patient/reference)0+1+2+4-1-2-4GainLoss291Agilent/OGTAffymetrixTheAgilentHumanGenomeCGH+SNPMicroarrayisadualcolorarraycontaining60-meroligonucleotideCGHandSNPprobessynthesized

insitu

usingAgilent’sinkjetSurePrinttechnology.Itallowssimultaneousdetectionofcopynumberchangesandcopyneutralaberrations,suchaslossofheterozygosity(LOH)anduniparental

disomy(UPD),onthesamearray.301OligoMicroarrays

TechnologyTypeCoverageAffymetrixInsitusynthesisusingphotolithographySNP+non-polymorphic1x1.8M900KSNP900Knon-polymorphicAgilentInsitusynthesisusingprintingtechnologySNP+non-polymorphicNon-polymorphiconly4x44K,

8x60K,

2x105K,

4x180K,2x244KIlluminaOligosattachedtobeadsSNP+non-polymorphic4-12x250K-4MillionUnlikeSangerwhereeachalleleisonlycovered2xatthemost,NGScoverseachalleletenstothousandsoftimesdependingonassayMultipledifferenttypesofplatformsGenepanelsorwholeexomeDifferentamountsofcoverageNextGenerationSequencing(NGS)32Roche/454FLX:2004IlluminaSolexaGenomeAnalyzer:2006AppliedBiosystemsSOLiDTMSystem:2007HelicosHeliscopeTM:recentlyavailablePacificBioscienciesSMRT:launching2010NGSPlatform33NGSsequencingExtractDNARandomfragmentationInsolutioncaptureExonen