OBJECTIVETo explore the molecular mechanisms involved in a pedigree with inherited coagulation factor X (FX) deficiency.

METHODSThe activated partial thromboplastin time (APTT), prothrombin time (PT), FX activity (FX:C) and FX antigen (FX:Ag) test were adopted for phenotype diagnosis. All the 8 exons, intron/exon boundaries and the 5'untranslated regions (UTR) of the FX gene were amplified by polymerase chain reaction (PCR) from the genomic DNA extracted from the peripheral blood of the propositus. The PCR products were screened by direct sequencing. The mutation was confirmed by allele specific PCR (ASPCR).

RESULTSThe phenotype of the propositus was identified as FX deficiency (type II). Two novel FX gene mutations were detected in the propositus: one was a donor site splice mutation in intron 1 (IVS1 + 1G-->A), another was a missense mutation 1185G-->A in exon 8 (Arg347His).

CONCLUSIONThe FX deficiency of the propositus is caused by double heterozygous mutations IVS1 + 1G-->A and Arg347His.