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1、Single-genedisorders1、TerminologyAllele:isalternativevariationsofgeneticinformationataparticularlocusonachoromosome.Genotype:isthesetofallelesthatmakeupaperson’sgeneticconstitutionatasinglelocus.Phenotype:istheobservableexpressionofagenotypeasamorphological,clinicalormoleculartrait.Homozygous:whena
2、personhasapairofidenticalallelesinalocus,heissaidtobehomozygous.Heterozygous:whentheallelesaredifferent,heissaidtobeheterozygous.Dominant:withadominantgeneticdisorder,oneabnormalcopyofthegenewillcausethedisease.Recessive:bothcopiesofthegenemustbeabnormalinorderforapersontobeaffectedbytheDisease.Ped
3、igree:isafamilytreewhichmadeupbysymbolsandlines,,representapatient'sgeneticfamilyHistory.Pedigreeanalysis:(1)Informationoffamilymembersmorethanthreegenerations家系越大越好,患者与正常人的信息都采(2)Informationverifiedbygeneticconsultant(3)Investigatingthedeathcause,deathage,consanguineousmarriage,fetaldeath,abortion
4、,neonataldeath(4)Determinethemodeofinheritance:遗传方式dominant,recessive,partialdominance,sex-linked,autosomal,mitochondrial,maternaleffect.母体效应(5)Determinetheprobabilityofanaffectedoffspringforagivencross.2、Patternsofsinglegenedisorders(1)FactorsdeterminedtheclassificationChromosomelocationDominantor
5、recessive(2)Basicpatternsofsinglegenedisorders DominantRecessiveAutosomalAutosomaldominant(AD)Autosomalrecessive(AR)X-linkedX-linkeddominant(XD)X-linkedrecessive(XR)Y-linkedY-linked3、AutosomalRecessive(AR)lDefinition:ARarepresentedonlyinindividualswhoarehomozygousforthemutantgeneonautosome.lCarrier
6、(Aa):Anindividualwhocarriesonegeneforaparticularrecessivetrait.Acarrierdoesnotexpressthetrait,whiletheycouldhaveanaffectedoffspringwhenmatingwithanothercarrier.lPedigreeCharacteristicsofAR(1)Affectsbothsexesequally(2)Achildofunaffectedcarrierparentshas25%riskofdisease(3)Fewaffecters,usuallyonlyinon
7、egeneration(4)IncreasedriskinconsanguineousmatinglCoefficientofrelationship亲缘系数Theprobabilitythatanytwoindividualsshareagivengeneatarandomlocusfromacommonancestor.lConsanguineousmating近亲婚配Consanguineousmati