本文于1988～1990年根据IX因子凝血功能和抗原水平的特殊改变,选择性地利用多聚合酶链反应(PCR)和直接核苷酸序列分析技术,对5个血友病B家庭的基因缺陷进行了研究.先后发现5种不同的点突变.其中3种属世界上尚未报道的新突变 This article from 1988 to 1990 according to the special factors of coagulation function and antigen level of factor VIII, selective use of polymerase chain reaction (PCR) and direct nucleotide sequence analysis technology, 5 hemophilia B family gene defects Five different point mutations were identified, three of which were not yet reported in the world