Congenital factor X (FX) deficiency is a rare bleeding disorder with an incidence of one in one million. The proband, a 2-year-old girl, exhibited easy bruising and a history of umbilical cord bleeding at birth. Prothrombin time (> 40 s) and activated partial thromboplastin time (65.0 s) were prolonged. Marked declines in FX activity (< 1%) and FX antigen levels (5%) were also observed. Genetic analysis of the proband identified two types of single-base substitutions, c.353G>A (p.Gly118Asp) and c.1303G>A (p.Gly435Ser), indicating compound heterozygous congenital FX deficiency. Genetic analysis of family members revealed that her father and older sister (5-year-old) were also heterozygous for p.Gly118Asp, and that her mother was heterozygous for p.Gly435Ser. To improve the bleeding tendency, the proband received regular replacement of 500 units of PPSB-HT, a prothrombin complex concentrate (PCC). Following continued regular replacement of 500 units of PPSB-HT once per week, the proband has exhibited no bleeding tendencies and no new bruises have been observed. There are no previous report of the use of PPSB-HT for regular FX replacement. Regular replacement therapy with PPSB-HT may be an effective method for preventative control of bleeding tendencies in FX deficiency.

中文翻译：

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先天性因子X缺乏症的复合杂合患者的遗传分析和凝血酶原复合浓缩物的常规替代疗法

先天性因子X（FX）缺乏症是一种罕见的出血性疾病，发病率为百万分之一。该先证者是一名2岁女孩，在出生时表现出容易瘀伤和脐带出血的病史。凝血酶原时间（> 40 s）和活化的部分凝血活酶时间（65.0 s）延长。还观察到FX活性（＜1％）和FX抗原水平（5％）的显着下降。先证者的遗传分析确定了两种类型的单碱基取代，c.353G> A（p.Gly118Asp）和c.1303G> A（p.Gly435Ser），表明复合杂合性先天性FX缺乏。对家庭成员的遗传分析表明，她的父亲和姐姐（5岁）对p.Gly118Asp也是杂合的，而她的母亲对p.Gly435Ser也是杂合的。为了改善出血趋势，先证者定期更换500个单位的凝血酶原复合浓缩物（PCC）PPSB-HT。每周一次持续定期更换500单位的PPSB-HT，先证者无出血倾向，也未见新伤痕。以前没有关于使用PPSB-HT进行常规FX更换的报告。定期用PPSB-HT替代疗法可能是预防控制FX缺乏症出血倾向的有效方法。