Analysis of a case of hereditary anomalous fibrinogenemia complicated with deep vein thrombosis due to the c.2185G＞A vari-ant of FGA gene / 临床检验杂志

ABSTRACT

Objective To analyze the deep venous thrombosis(DVT)after plasma infusion in a patient with congenital dysfibrinogene-mia(CD),and explore the relationship between the CD and DVT.Methods The clinical data were collected and the pedigree was investigated(3 subjects of 2 generations in total).The relevant indexes of coagulation factors of the patient and her family members were detected.The genomic DNA of peripheral blood was extracted for PCR amplification.All the exons,flanking sequences,5'and 3'untranslated regions of FGA,FGB and FGG genes of fibrinogen(Fg)of the patient were analyzed by direct sequencing.The corre-sponding mutation site was subjected to sequence in the other members of this family.The PyMol software was used to construct the pro-tein model before and after gene mutation.Results The patient was admitted to hospital for hysteromyomectomy.DVT appeared in 3 days after surgery.The prothrombin time(PT),thrombin time(TT),Fg activity(Fg∶C)and Fg antigen(Fg∶Ag)of the patient was 14.9 s,33.3 s,0.94 g/L and 2.10 g/L,respectively.The above four indicators in her mother were 14.7 s,32.8 s,0.97 g/L and 2.35 g/L,respectively.Gene sequencing revealed that both the patient and her mother had a heterozygous missense mutation c.2185G＞A(p.Glu729Lys)in exon 6 of the FGA gene.The protein model analysis demonstrated that p.Glu729Lys mutation changed the amino acid side chain and reduced the number of hydrogen bonds originally formed with Arg854.Conclusion A heterozygous missense mutation c.2185G＞A(NM_000508)in exon 6 of the FGA gene should be responsible for the low fibrinogen level in this pedigree,which might be the main reason for DVT after plasma infusion in this patient.