[Gene analysis of a combined inherited factor VII and factor X deficiency pedigree].

OBJECTIVE

To perform gene analysis and family survey of a patient with combined inherited FVII and FX deficiency, and to identify the gene mutation of this patient.

METHODS

The phenotype diagnosis was validated by coagulant parameter assay on prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, FVII and FX activity (FVII:C, FX:C) and FVII and FX antigen (FVII:Ag, FX:Ag). FVII and FX gene mutations were analyzed in the proband and other family members by DNA direct sequencing of all exons, exon-intron boundaries and 5', 3' untranslated sequences. One hundred and six health examination participants were selected as control.

RESULTS

The values of PT and APTT of the proband showed significantly prolonged, which were 84.5s and 63.4s, respectively. The levels of FVII:C, FVII:Ag, FX:C and FX:Ag were 6%, 7%, 4% and 30%, respectively. The PT of his father, mother and sister was prolonged slightly while both APTT and FVII:Ag were in the normal range. Two homozygous mutations, g.11267C→T in exon 8 of FVII gene resulting in the substitution of Arg277Cys and g.28139G→T in exon 8 of FX gene leading to the substitution of Val384Phe, were identified in the proband. The proband's parents and sister were heterozygous for Arg277Cys and Val384Phe mutations.

CONCLUSION

Homozygous mutation Arg277Cys in FVII gene and Val384Phe in FX gene were the molecular mechanism causing combined inherited FVII and FX deficiency. The Val384Phe substitution was a novel mutation, which may affect the synthesis or secretion of FX protein.