Investigation on gene defects in a pedigree with inherited coagulation factor XI deficiency

Abstract

Objective To investigate the gene defects of a pedigree with inherited coagulation factor Ⅺ (FⅪ) deficiency by analyzing its phenotype and molecular genetic characteristics. Methods A pedigree with inherited FⅪ deficiency was enrolled in this study. The activated partial thromboplastin time (APTF), prothrombin time (PT), FⅪ activity (FⅪ: C) and FⅪ antigen (FⅪ: Ag) were determined for phenotype diagnosis. Fifteen exons and their flanks of F11 gene from the proband's genomic DNA were amplified by polymerase chain reaction (PCR), and the PCR products were directly sequenced to analyze the F11 gene mutation. The PCR products amplified from genomic DNA from the proband, her parents and 100 healthy donors were digested with restriction enzyme BssSI to exclude gene polymorphism and confirm the mutation site. The cleavage site in the signal peptide was predicted by the SignalP software. Results The values of APTT, PT, FⅪ: C and FⅪ: Ag of the proband were 69.5 s, 12.3 s, 2.6% and 2.5%, respectively, indicating that this case was cross-reacting material (CRM) negative. The same values of healthy controls were 35 s, 13 s, 100% and 100%, respectively. As compared with Genbank AY191837 sequence, four variants in F11 exons were found. G3733C heterozygous mutation in exon 2 causod Gly to Arg substitution at-1 amino acid position in signal peptide (G-1R). The G3733C mutation in exon 2 introduced a new BssSI enzyme digestion site. Further analysis of the 100 randomly collected DNA samples from the normal population excluded the possibility of G3733C as a polymorphism. CI6642T heterozygous mutation in exon 8 introduced a premature stop codon at 263 amino acid position (Q263Term). Conclusions G-1R mutation and Q263Term compound heterozygous mutation in F11 gene are the mechanism of FⅪ deficiency for the proband. G-1R mutation is a novel F11 gene mutation causing inherited FⅪ deficiency. Key words: Factor Ⅺ deficiency; Blood coagulation disorders, inherited; Prothrombin; Mutation; Pedigree