Objective:To identify and diagnose the mutations of coagulation factor Ⅸ gene for the patients and probable carriers in three unrelated pedigrees with haemophilia B, in order to establish pedigree chart, and provide criterion of genetic counseling or prenatal consultation for other family members. Methods: Subjects' DNA was extracted. Eight coding exons of FⅨ gene in the three family members were amplified by PCR, then sequenced by sanger dideoxy chain-termination method. The results were analysed. Results: Three mutations of FⅨ gene were detected in the probands: the proband's gene mutation of the NO. 1 pedigree in exon 5:22724dell (Alal 64GInfsX10) , the proband's gene mutation of the NO. 2 pedigree in exon 6:25510_255Mdel5 (Gly236Ilefs X6) , the proband's gene mutation of the NO. 3 pedigree in exon 7:35068 _35070 del3 (V263del) , these mutations were all unreported. There were one carrier be found in NO. 3 pedigree, the type was same as the proband of the NO. 3 pedigree. Conclusion: The genetic diagnosis established pedigree chart for the three pedigrees, the results not only complemented the haemophilia B mutation database, but also provided the molecular basis for the pathogenesis.%目的:对3个无关联家系的血友病B患者及可能携带者进行基因诊断与分析,以建立家系图谱,为家系的遗传咨询及产前诊断提供依据.方法:提取实验对象DNA,运用PCR扩增及sanger双脱氧链终止法对3个家系成员的FⅨ基因8个外显子序列进行测序比对,并对结果进行分析.结果:3个家系先证者中共发现了3种突变:家系1中先证者基因突变位于第5号外显子,类型为22724del1 (Ala164Glnfs10),家系2中先证者基因突变位于第6号外显子,类型为25510_25514del5 (Gly236Ilefs6),家系3中先证者基因突变位于第7号外显子,类型为35068_35070del3 (Val263del),均为未经报道的突变类型,其中家系3中发现携带者1例,基因突变类型与家系3中先证者基因突变类型相同.结论:本次基因诊断为3个家系建立了家系图谱,其结果不仅补充了血友病B的突变数据库,也为血友病B发病的分子机制提供了一定分析依据.
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