A novel fibrinogen variant in a Chinese pedigree with congenital dysfibrinogenemia caused by FGA P. Arg38Thr mutation: A case report

RATIONALE: Congenital dysfibrinogenemia (CD) is characterized by altered functional properties of the fibrinogen; people who suffer from CD often have a low activity of fibrinogen and the mutation in the genomic DNA. PATIENT CONCERNS: A 6-year-old child was examined with a low activity of fibrinogen measured by Von Clauss method and PT-derived method which indicated a normal level of fibrinogen; this abnormality was also detected in her mother. The genomic DNA of all the family members was extracted, and all exons of 3 fibrinogen genes which encode fibrinogen alpha chain (FGA), fibrinogen beta chain (FGB), and fibrinogen gamma chain (FGG) were amplified by polymerase chain reaction (PCR), in addition, sanger sequencing, homologous sequence alignment and bioinformatics software were performed for the further analysis. DIAGNOSES: CD in this pedigree is associated with c.113G>C in the exon 2 of FGA which caused Arg38Thr mutation. OUTCOMES: The child and her mother showed a low plasma concentration of fibrinogen measured by Von Clauss method, whereas a normal result measured by PT-derived method; finally, c.113G>C in the exon 2 of FGA was detected in the pedigree which caused Arg38Thr mutation and it is the first report on a pedigree with CD caused by AαArg38Thr. LESSONS: This case gives us the lesson that not all patients with CD showed typical symptoms and laboratory test results; the result of fibrinogen concentration and antigen which is tested by Von Clauss method and immunoturbidimetric assay is various according to the condition of each CD patient.