[Functional analysis of heterozygous plasma dysfibrinogens derived from two families of gammaArg275Cys and three families of gammaArg275His, and haplotype analysis for these families].
We have identified five heterozygous dysfibrinogenemias, two families with variant fibrinogen gammaArg275Cys (CGC > TGC; Matsumoto III and Sendai) and three families with gammaArg275His (CGC > CAC; Otsu II, Iida, and Shizuoka), from PCR-amplified DNA fragments and direct sequence analysis. gammaArg275 is the most important residue in fibrinogen for the so-called "D-D interface" in protofibril elongation. We compared the functions of plasma fibrinogen purified from affected family members with gammaArg275Cys and gammaArg275His. Both fibrinogens showed markedly impaired thrombin-catalyzed fibrin polymerization in comparison with normal controls. The degree of impairment of gammaArg275Cys fibrinogen was greater than that of gammaArg275His. These results were consistent with the fibrinogen concentration ratio (thrombin time method/immunological method). That is, the ratio of gammaArg275Cys was significantly lower than that of gammaArg275His. Moreover, scanning electron microscopy indicated significantly thicker fibers in fibrin clots made from gammaArg275Cys than in those of normal controls or gammaArg275His, and abnormal bundles with tapered ends. Factor XIIIa-catalyzed cross-linking of the fibrinogen gamma-chain (in the absence of thrombin) showed a similar delay for gammaArg275Cys and gammaArg275His. We report markedly impaired fibrin polymerization of gammaArg275Cys compared to gammaArg275His, and speculate that the difference is due to the disulfide-linked Cys in gammaArg275Cys, as we have already demonstrated for plasma and recombinant mutant fibrinogens. These results also indicate that an amino acid substitution of gammaArg275 disrupts D:D interactions in fibrin fiber formation. Furthermore haplotype analysis for three families with gammaArg275His suggested that founder of Iida family might be different from that of Otsu II or Shizuoka family.
Kamijyo
Yuka
Y
Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University, Matsumoto, Japan.
Hirota-Kawadobora
Masako
M
Fujihara
Noriko
N
Wakabayashi
Saki
S
Matsuda
Kazuyuki
K
Yamauchi
Kazuyoshi
K
Terasawa
Fumiko
F
Okumura
Nobuo
N
Honda
Takayuki
T
D015241:Fibrinogens, Abnormal / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D018740:Genetic Heterogeneity; D006239:Haplotypes; D006801:Humans
D015241:Fibrinogens, Abnormal