[Analysis on the novel compound heterozygous mutation FⅪ of a patient with hereditary factor Ⅺ deficiency].

Objective: To investigate the clinical phenotype and genotype characteristics of a Chinese hereditary factor Ⅺ deficiency pedigree. Methods: The activated partial thromboplastin time (APTT), prothrombin time (PT), FⅪ activity (FⅪ: C) were measured by clotting method using automatic coagulation analyzer. The FⅪ antigen (FⅪ: Ag) was assayed by enzyme-linked immunosorbent assay (ELISA). Fifteen exons of F11 from the proband and his pedigree members were amplified by polymerase chain reaction (PCR), then sequenced. Pymol software was used to analyze the novel mutations. Results: APTT, FⅪ: C and FⅪ: Ag of proband was 74.2 s, 4.0% and 2.9%, respectively. For his older sister, APTT, FⅪ: C and FⅪ: Ag was 67.1 s, 3.0% and 1.8%, respectively. APTT, FⅪ: C and FⅪ: Ag of healthy controls were 34.5 s, 100.0% and 100.0%. FⅪ: C of proband's father, mother and brother were 72.0%, 62.0%, and 78.0%, respectively. FⅪ: Ag of them were 50.0%, 43.0%, and 51.8%, respectively. The other coagulant parameters of the proband and his pedigree were all in the normal range. Sequence analysis showed two heterozygous gene mutations in F11 of the proband and his older sister. One was a deletion of T at nucleotide 1 491 in exon 12, resulting in a frameshift. A substitution of leucine 465 by tryptophan and a terminal coden after 7 amino acid: F11NM_13142c.1491delT (p.Leu465Trp.fs*7). The other was a G to A substitution at nucleotide 1 815 in exon 15, resulting in a substitution of glycine 573 by aspartic acid: F11 NM_13142c.1815G>A (p.Gly573Asp). F11NM_13142c.1491delT (p.Leu465Trp.fs*7) heterozygotes were found both in the proband's father and his brother while p. Gly573Asp heterozygote was only found in his mother. F11 of the proband's uncle was wild. Conclusion: The novel compound heterozygous mutations of F11NM_13142c.1491delT (p.Leu465Trp.fs*7) and F11 NM_13142 c. 1815G>A (p.Gly573Asp) are responsible for FⅪ deficiency to the proband, which induced the decrease of FⅪ: C and FⅪ: Ag.目的： 分析一个中国汉族遗传性凝血因子Ⅺ(FⅪ)缺陷症家系的表型和基因缺陷特征，探讨F11基因的突变类型和临床表型的关系。 方法： 采用凝固法检测先证者及家系成员的活化部分凝血活酶时间(APTT) 、凝血酶原时间(PT)、凝血因子Ⅺ活性(FⅪ：C)等指标进行表型诊断；酶联免疫吸附测定方法(ELISA)检测凝血因子Ⅺ抗原(FⅪ：Ag)；提取外周血基因组DNA，对先证者及家系成员F11基因1～15号外显子及侧翼序列进行PCR扩增和测序，对105名健康对照者DNA相应突变区域进行PCR扩增和测序，与人类基因组突变数据库比对寻找突变位点并排除基因多态性；使用Pymol软件分析突变对FⅪ蛋白质结构及功能的影响。 结果： 先证者APTT为74.2 s，FⅪ：C为4.0%，FⅪ：Ag为2.9%；先证者姐姐APTT为67.1 s，FⅪ：C为3.0%，FⅪ：Ag为1.8%；健康对照者APTT为34.5 s，FⅪ：C为100.0%，FⅪ：Ag为100.0%；先证者父、母和弟弟FⅪ：C分别为72.0%、62.0%、78.0%；FⅪ：Ag分别为50.0%、43.0%、51.8%。先证者及家系成员其他凝血指标均正常。测序发现先证者及其姐姐F11存在双重杂合突变，外显子12的1 491位碱基T缺失导致了移码突变，使465位氨基酸由亮氨酸突变为色氨酸，在突变位点后第7位出现终止密码子：F11NM_13142c.1491delT(p.Leu465Trp.fs*7)；外显子15的1 815位碱基G变为A，密码子由GGC变为GAC，导致错义突变F11 NM_13142 c．1815G>A(p.Gly573Asp)。其父和其弟弟为F11NM_13142c.1491delT(p.Leu465Trp.fs*7)杂合突变者；其母为p.Gly573Asp杂合突变者，先证者舅舅F11基因为正常野生型。 结论： F11NM_13142c.1491delT(p.Leu465Trp.fs*7)和F11NM_13142c.1815G>A(p.Gly573Asp)双重杂合突变是导致先证者遗传性FⅪ缺陷症的分子致病原因，引起FⅪ抗原和活性同时降低。.