Wen-Bin Wang and Qi-Hua Fu contributed equally to this work and should be considered as co-first author.
Molecular characterization of two novel mutations causing factor X deficiency in a Chinese pedigree
Article first published online: 21 JAN 2005
Volume 11, Issue 1, pages 31–37, January 2005
How to Cite
Wang, W.-B., Fu, Q.-H., Zhou, R.-F., Wu, W.-M., Ding, Q.-L., Hu, Y.-Q., Wang, X.-F., Wang, H.-L. and Wang, Z.-Y. (2005), Molecular characterization of two novel mutations causing factor X deficiency in a Chinese pedigree. Haemophilia, 11: 31–37. doi: 10.1111/j.1365-2516.2005.01063.x
- Issue published online: 21 JAN 2005
- Article first published online: 21 JAN 2005
- Accepted after revision 1 December 2004
- factor X;
- splice site
Summary. Factor X (FX) deficiency is a rare bleeding disorder inherited as an autosomal recessive trait. In this study, we investigated the molecular basis of FX deficiency in a Chinese pedigree. The proposita showed a markedly prolonged activated partial thromboplastin time and a mild prolongation of prothrombin time. The levels of FX antigen and FX activity were 58.6% and 2.5%, respectively. Molecular analysis revealed that the proposita was compound heterozygous for two novel mutations: IVS1 + 1G > A and G1185A (Arg347His). The aberrant transcripts from the IVS1 + 1G > A mutant allele were not detected by analyzing the splicing pattern of ectopic transcripts in leukocytes of the patient with nested polymerase chain reaction after reverse transcription. We thus hypothesize that the mRNA molecules originating from the IVS1 + 1G > A mutation were rapidly destroyed in vivo. Site-directed mutagenesis of FX cDNA was used to introduce FXG1185A mutation, and wild-type as well as mutant FX proteins were expressed by transient transfection in HEK 293 cells. Normal FX antigen levels both in the conditioned media of cells expressing the mutant and in cell lysates were detected by an enzyme-linked immunoadsorbent assay. Evaluation of wild-type and mutant coagulant activity demonstrated that the FX molecules carrying the Arg347His mutation have dramatically decreased activity.