人类因子IX基因缺陷的研究

STUDY ON GENE DEFECTS OF HUMAN FACTOR IX

本实验对同一家系3例血友病乙男患者进行因子IXI基因缺陷的研究,应用多聚酶链反应扩增因子IX基因外显子2的338bp DNA片段,扩增产物行单链构型多态性(SSCP)检查,发现三例均出现多态性变化.纯化该三例PCP扩增产物DNA,并行双链DNA直接荧光自动测序,发现三例都在6364位发生碱基替换,C(CGG)→T(TGG),该基因点突变改变了正常FIX的结构和凝血功能,因而导致血友病乙.该研究对揭示血友病乙分子缺陷的发生机制有重要意义,并有助于血友病.乙携带者的检查和产前基因诊断,而且对血友病己患者的基因治疗有直接指导意义.

To define the precise genetic defects of hemophilia B. We have used the polymerase chain reaction ( PCR ), Single-Strand conformation Polymorplism (SSCp ) combined with direct sequencing to analyze the amplified DNA fragments contaning the entire exon Ⅱ of the factorⅨ gene from 3 patients with hemophilia B. Analysis of their factorⅨ genes revealed a G to T transition at nucleotide residue 6364 in exonⅡof the propeptide region. This caused a change of amino acid at-4 from Arg to Trp. This point mutation blocks the cleavage site involved in the release of the propetide which reduced factor Ⅸclotting activity.This study offers the possibility of direct analysis in carrier and prenata diagrosis in kindreds with this mutation.