单基因遗传病ppt课件

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1、单基因遗传病BasicConceptionDominant——AHomozygote——AAoraaHeterozygote——AaGenotype&PhenotypeRecessive——aWhat’sMonogenicDisorders?ThediseasesthataretheresultofasinglemutantgenethathasalargeeffectonphenotypeandthatareinheritedinsimplepatternssimilartooridenticalwiththosedescribedbyMendelforcertaindiscretechar

2、acteristicsingardenpeas.TheBasicPatternsofSingleGeneInheritanceAutosomalDominantAutosomalRecessiveX-linkedDominantX-linkedRecessiveY-linkedInheritanceOMIMStatisticsforSept.13,2005Autosomal15212X-linked906Y-linked56Mitochondrial6216236http://www.ncbi.nlm.nih.gov/Omim/mimstats.htmlPEDIGREES:Theyaregra

3、phicrepresentationsofafamilytreewhichshowthebiologicalrelationshipoftheindexcase,orprobandorpropositus(先证者)totherestoftheindividuals.Symbolsareusedtoillustratethevariousstatesandrelationshipsofthefamilytree.常染色体显性遗传AutosomalDominantInheritanceADdiseasesarethoseinwhichasinglecopyofamutantgeneonautoso

4、meisenoughforthetraittobeexpressedorshown.AutosomalDominant(AD)婚配类型和子代发病风险PedigreeCharacteristicsAaaaP×1:1F1gameteEachaffectedindividualhasoneaffectedparent50%ofoffspringareaffectedMalesandfemalesareaffectedwithequalprobabilityPassedinaverticalfashionPedigreeCharacteristics系谱特征1.遗传与性别无关，男女受累的机会均等2.患

5、者父母必有一方受累3.每代都可出现患者，在连续世代中呈垂直分布。偶尔由于外显不足而出现隔代遗传的现象4.双亲无病时，子代一般均正常(除非新的基因突变)◆30～40岁发病，也有10多岁或60岁以后发病◆有进行性不自主的舞蹈样动作，可合并肌强直◆可出现神经症状，如抑郁，智能衰退，最终成为痴呆Huntington舞蹈症Huntington’schoreaMechanismoftheDisorder◆HD基因位于4p16.3，致病基因编码区IT155’端具有(CAG)n三核苷酸重复。正常人9～34次，患者重复37～100次。且CAG重复的多少与疾病的早晚、严重程度成正比。◆有遗传印记或早现（genet

6、icimprintingoranticipation）现象PathobiologyChangeCLINICALEXAMPLESFamilialhypercholesterolemia(家族性高胆固醇血症)Polysystickidneydisease,adult(成年多囊肾病)Alpha-thalassemias(α-地中海贫血)Brachydactyly,typeA1[短指(趾)症A1型]Neurofibromatosis,type1(神经纤维瘤)常染色体隐性遗传AutosomalRecessiveInheritanceP×1:1:1:1F1PedigreeCharacteristicsga

7、mete×1:1BothparentsarecarriersThediseasesaresporadicTheriskofoffspringishigherinconsanguineousmarriage1/4ofsibsareaffected.MalesandfemalesareaffectedwithequalprobabilityPedigreeCharacteristics2/3ofuna