[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.