Identification of a dysfibrinogenemia of γR275C (Fibrinogen Fukushima)

Background: Various dysfibrinogenemias have been identified worldwide. This paper describes a case of dysfibrinogenemia recently identified in our laboratory. Patient: A 34-year-old pregnant woman without any clinical complaints was admitted to our hospital for delivery. She had an extremely low fibrinogen concentration as determined by the thrombin time method though immunoassay showed a titer within the reference range. Dysfibrinogenemia was suspected and further analyses were performed including on her family. Thrombin time was measured using human and bovine thrombin with and without calcium ion. Reptilase time was also measured. To identify the genetic mutation responsible for this dysfibrinogen, genomic DNA extracted from the blood was analyzed for mutation-rich regions in the fibrinogen gene. Results: The subject, her mother and her two infants showed the same pattern of results while her father showed a regular pattern. Thrombin time calculated using both human and bovine thrombin and reptilase time was elongated in the propositus. The extent of the elongation was decreased in the presence of calcium ion. DNA sequencing showed heterogeneous fibrinogen γR275C mutations in the propositus, mother and two children. The father showed no mutation. Conclusions: A case of dysfibrinogenemia γR275C without any clinical symptoms was found by routine coagulation testing and was genetically identified.