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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
