[A case of inherited afibrinogenemia caused by an IVS7-12A>G splice mutation of FGG gene].

OBJECTIVE To explore the genetic basis for a Chinese pedigree affected with inherited afibrinogenemia. METHODS For the proband and his family members, prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), Fibrin(ogen) degradation products (FDPs), D-dimer (D-D), plasminogen activity (PLG:A) and the TT mixed experiment with protamine sulfate were determined with a STAGO-R automatic coagulation analyzer. The activity and antigen of fibrinogen (Fg) in plasma were measured with the Clauss method and immunonephelometry method, respectively. All exons and flanking regions of the fibrinogen genes (FGA, FGB and FGG) were amplified by PCR and directly sequenced. Human Splicing Finder software was used to predict and score the change of splicing site caused by the mutation. RESULTS The proband showed normal FDPs and D-D but significantly prolonged TT, PT and APTT. The activity and antigen of fibrinogen in plasma were significantly decreased ( G (g.4147A>G) mutations of the FGG gene, for which his parents and young sister were heterozygous. As predicted by Human Splicing Finder and Mutation Taster software, the variant may generate a new splicing site which can extend the sequence of exon 7 by 11 bp, with alteration of the coding sequence. PROVEAN suggested the variant to be deleterious. CONCLUSION The afibrinogenemia of the proband may be attributed to the FGG IVS7-12A>G variant, which was unreported previously.