title: Differences in the function and secretion of congenital aberrant fibrinogenemia between heterozygous γD320G (Okayama II) and γΔN319-ΔD320 (Otsu I).
abstract: BACKGROUND
  We encountered two patients with hypodysfibrinogenemia and designated them as Okayama II and Otsu I. Although the affected residue(s) in Okayama II and Otsu I overlapped, functionally determined fibrinogen levels and the ratio of functionally to immunologically determined plasma fibrinogen levels were markedly different.
  
  
  METHODS
  DNA sequence and functional analyses were performed for purified plasma fibrinogen. A recombinant protein was synthesized in Chinese hamster ovary (CHO) cells to determine the secretion of variant fibrinogens.
  
  
  RESULTS
  A heterozygous A>G in FGG, resulting in γ320Asp>Gly for Okayama II, and a heterozygous deletion of AATGAT in FGG, resulting in the deletion of γAsn319 and γAsp320 (γΔN319-ΔD320) for Otsu I, were obtained. SDS-PAGE and Coomassie staining revealed that the variant γ-chain was not clear in Okayama II, but was clearly present in Otsu I. The lag period for the fibrin polymerization of Okayama II was slightly slower than that of the normal control, whereas Otsu I fibrinogen indicated no polymerization within 30 min. Both variant γ-chains were synthesized in CHO cells and assembled into fibrinogen; however, the fibrinogen concentration ratio of the medium/cell lysate of γ320Gly was six-fold lower than that of γΔN319-ΔD320.
  
  
  CONCLUSIONS
  We concluded that the plasma fibrinogen of Okayama II, constituted by a lower ratio of the variant γ-chain, led to the almost normal functioning of fibrin polymerization. However, the plasma fibrinogen of Otsu I, with a higher ratio of the variant γ-chain, led to marked reductions in fibrin polymerization.
authors.affiliation: Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan; Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan.
authors.forename: Saki
authors.initials: S
authors.lastname: Mukai
authors.affiliation: Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan; Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan.
authors.forename: Minami
authors.initials: M
authors.lastname: Ikeda
authors.affiliation: Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Takezawa
authors.affiliation: Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Sugano
authors.affiliation: Department of Laboratory Medicine, Graduate School of Medicine, Shinshu University, Matsumoto, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Honda
authors.affiliation: Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan. Electronic address: nobuoku@shinshu-u.ac.jp.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Okumura
mesh_terms: D000328:Adult; D000347:Afibrinogenemia / Q000097:blood / Q000235:genetics*; D000818:Animals; D001777:Blood Coagulation; D016466:CHO Cells; D002384:Catalysis; D006224:Cricetinae; D003412:Cricetulus; D003432:Cross-Linking Reagents / Q000737:chemistry; D026122:Factor XIIIa / Q000737:chemistry; D005260:Female; D005337:Fibrin / Q000235:genetics* / Q000378:metabolism; D005340:Fibrinogen / Q000235:genetics* / Q000378:metabolism; D015241:Fibrinogens, Abnormal / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D006579:Heterozygote; D006801:Humans; D010314:Partial Thromboplastin Time; D011517:Prothrombin Time; D011994:Recombinant Proteins / Q000737:chemistry; D017422:Sequence Analysis, DNA; D013917:Thrombin / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D015241:Fibrinogens, Abnormal; D011994:Recombinant Proteins; D005337:Fibrin; D005340:Fibrinogen; D026122:Factor XIIIa; D013917:Thrombin
keywords: Dysfibrinogenemia; Fibrinogen; Hypofibrinogenemia; Secretion; γ-Chain