We found and identified a novel heterozygous dysfibrinogenemia with gammaT305A (ACA --> GCA) mutation in a 6-month old boy. Since his plasma antigenic concentration of fibrinogen was 1.12g/l and less than the lower limit of the reference interval, we guessed that the production of a variant fibrinogen might be a partial defect. To clarify this speculation, we altered the gamma-chain expression vector, transfected it into Chinese Hamster Ovary(CHO) cells, and synthesized recombinant gammaT305A fibrinogen alongside three other variant fibrinogens, gammaS306P, gammaH307Y, and gammaN308K, and the wild type (gammaN) fibrinogen. Fibrinogen concentration ratio of culture media/cell lysates decreased in the order of gammaT305A-, gammaS306P-, gammaH307Y-CHO cells, all three being lower in comparison to the gammaN-CHO cells. Western blotting analyses indicated that all of variant gamma-chains were assembled into fibrinogen molecules in the cells. These data indicate the possibility that secretion of gamma T305A-fibrinogen is slightly impaired and variant fibrinogen is accumulated in the cell. Of interest, the secretion of gammaH307Y-fibrinogen was decreased the most, whereas that of the gammaN308K-CHO cells was not affected. The tertiary structure of the yC nodule indicated that gamma305T-gamma307H residues are located in the inside of the nodule. In contrast, that of gamma308N is located on surface of the nodule. In conclusion, our results showed the variant fibrinogen, gammaT305A, has characteristics not only of dysfibrinogenemia, but also might be hypofibrinogenemia, namely, hypo/dysfibrinogenemia. Furthermore, gamma306S-gamma307H residues of the gammaC nodule play crucial roles for protein synthesis and fibrin polymerization.