Hypofibrinogenemia associated with a heterozygous missense mutation gamma153Cys to arg (Matsumoto IV): in vitro expression demonstrates defective secretion of the variant fibrinogen

We genetically analyzed a case of hypofibrinogenemia that showed no bleeding or thrombotic tendency. Direct sequencing of a polymerase chain reaction-amplified gamma-chain gene segment showed a novel nucleotide substitution. This heterozygous mutation encodes both Cys (TGT) and Arg (CGT) at residue 153. To examine the basis for the fibrinogen deficiency, we prepared expression vectors containing mutant gamma-chain DNAs encoding gamma153R and gamma153A for in vitro expression in Chinese hamster ovary (CHO) cells. Enzyme-linked immunosorbent assay and immunoblot analysis of the culture media and cell lysates showed that CHO cells transfected with gamma153R or gamma153A synthesized the variant gamma-chain, but did not secrete variant fibrinogen into the culture medium. Metabolic pulse-chase experiments showed that fibrinogen assembly was impaired when either variant gamma-chain was expressed. In cells expressing normal fibrinogen, assem- bly intermediates and intact fibrinogen were seen in cell lysates prepared after short (3 minutes) or long (1 hour) incubation with (35)S-methionine. Neither intermediates nor intact fibrinogen was seen with the variant gamma-chains. These data suggest that gamma-chains have an important early role in fibrinogen assembly. Thus, our results support the model for fibrinogen assembly proposed by Huang et al (J Biol Chem 268:8919, 1993), in which the first step in assembly is the formation of alphagamma or betagamma dimers, or both. This model implies that gammaCys153 has a critical role in the formation of these early assembly intermediates. We concluded that the gamma153Cys-->Arg substitution does not allow fibrinogen assembly and secretion, and this is manifest in vivo as a fibrinogen deficiency. We designated this variant as fibrinogen Matsumoto IV.

[A case positive for the inhibitor for coagulation factor V]

We report a 71-year-old man who exhibited hepatocellular carcinoma and the inhibitor for coagulation factor V (FV). The inhibitor was found when his coagulation screening tests revealed an abnormally prolonged prothrombin time (71.1 sec) and activated partial thromboplastin time (more than 120 sec) but normal values of fibrinogen (241 mg/dl), the thrombo test (84%) and hepaplastin test (71%). In addition, FV-coagulation activity of the patient's plasma showed less than 1% of the pooled normal plasma and inhibitory activity for FV of his plasma was 32 Bethesda units. This inhibitory activity was neutralized by the addition of anti-human immunoglobulin-gamma-chain serum. The patient was treated with a fibrin sealant including human thrombin when he underwent an partial hepatectomy (32 months before onset) and received 2 doses of thrombin orally (5 months and 2 weeks before onset) to stop bleeding from phlebeurysm. Several studies have reported that the inhibitor for FV was produced after treatment with bovine thrombin containing FV as a contaminant. These findings suggest that our patient may produce an immunoglobulin specific for FV after similar stimulation of human thrombin containing FV.

Genetic relationship and distribution of the Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (Sus scrofa riukiuanus) analysed by mitochondrial DNA

Mitochondrial genetic variations were used to investigate the relationships between two Japanese wild boars, Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (S.s. riukiuanus). Nucleotide sequences of the control (27 haplotypes) and cytochrome b (cyt-b) regions (19 haplotypes) were determined from 59 Japanese wild boars, 13 Ryukyu wild boars and 22 other boars and pigs. From phylogenetic analyses, the mtDNA of Ryukyu wild boar has a distinct lineage from that of Japanese wild boar, which was classified into the Asian pig lineage. This result suggests that the Ryukyu wild boar has a separate origin from the Japanese wild boar.

Fibrinogen Matsumoto III: a variant with gamma275 Arg-->Cys (CGC-->TGC)--comparison of fibrin polymerization properties with those of Matsumoto I (gamma364 Asp-->His) and Matsumoto II (gamma308 Asn-->Lys)

Fibrinogen Matsumoto III (M-III) is a dysfibrinogen identified in a 66-year-old woman with rectal cancer. The fibrinogen level determined by the thrombin-time method was markedly decreased in preoperative coagulation tests of her plasma. Three fibrinogen polypeptide-chain gene fragments from the proposita were amplified by the polymerase chain reaction method, then sequenced. The triplet CGC encoding the amino acid residue gamma275 was replaced by TGC, resulting in the substitution of Arg->Cys. There have been previous reports of nine families with the same alteration, nine families with an Arg->His variant and one family with an Arg->Ser variant in this residue, which has been shown to be one of the most important amino acids in the 'D:D' interaction site. In addition, there are three silent mutations in the Aalpha-chain gene and two mutations in the intron of the Bbeta-chain and the gamma-chain gene. However, none of these mutations is thought to be the cause of the dysfunctional fibrinogen. The thrombin-catalyzed fibrin polymerization in the presence of 1 mM Ca ions was markedly delayed in purified M-III. Its lag period was longer than those of Matsumoto II (M-II; gamma308Asn->Lys) and Matsumoto I (M-I; gamma364Asp-His). gamma364Asp is one of the most important residues in the polymerization pocket of the 'D:E' interaction site and gamma308Asn is located in the vicinity of a high affinity Ca2+ binding site in the D-domain, gamma311-336. The maximum slope of the polymerization curve for M-III was about 4-fold steeper than that for M-1 but less steep than that for M-II. These results may suggest that the tertiary structure of the polymerization pocket plays a more important role in the lateral aggregation of protofibrils than that of the 'D:D' interaction site.

Interaction of neuronal nitric-oxide synthase with alpha1-syntrophin in rat brain

Neuronal nitric-oxide synthase (nNOS) has a PSD-95/Dlg/ZO-1 (PDZ) domain that can interact with multiple proteins. nNOS has been known to interact with PSD-95 and a related protein, PSD-93, in brain and with alpha1-syntrophin in skeletal muscle in mammals. In this study, we have purified an nNOS-interacting protein from bovine brain using an affinity column made of Sepharose conjugated with glutathione S-transferase-rat nNOS fusion protein and identified it as alpha1-syntrophin by microsequencing. Immunostaining of primary cultures of rat embryonic brain neuronal cells with antibodies against these proteins showed that nNOS and alpha1-syntrophin were colocalized in neuronal cell bodies and neurites. Immunohistochemical analysis indicated that the nNOS- and alpha1-syntrophin-like immunoreactive substances were highly expressed in the rat hypothalamic suprachiasmatic nucleus (SCN) and paraventricular nucleus. In the SCN, nNOS- and alpha1-syntrophin-like immunoreactive substances were colocalized in the same neurons as detected by confocal microscopy. These results indicate that nNOS in brain interacts with alpha1-syntrophin in specific neurons of the SCN and paraventricular nucleus and that this interaction might play a physiological role in functions of these neurons.

[Undiagnosed lung cancer complicated by intracavitary aspergillosis]

A 54-year-old man was treated with an antifungal agent (itraconazole) for post-tuberculous intracavitary aspergillosis. Though clinical and radiological findings indicated that the patient's symptoms had gone into remission, aspergillosis recurred 4 months after the cessation of antifungal chemotherapy, requiring that the patient undergo an operation. Intraoperative and pathological findings revealed a squamous cell carcinoma contiguous to the cavity containing the aspergilloma. Though a few cases of aspergilloma within cavitating pulmonary carcinomas have been reported in the literature, the case of lung cancer we report was thought to arise from preformed lung scars surrounding a post-tuberculous cavity that contained an aspergilloma. Although conclusive distinctions between neoplasms and fungal infections are difficult to make, careful observation of the radiographic features is necessary when treating patients with fungus ball-type aspergillosis.

Plasminogen Kanagawa-I, a novel missense mutation, is caused by the amino acid substitution G732R

A new dysplasminogen, plasminogen Kanagawa-I, was identified in a healthy male with no previous thrombotic episodes. His plasma plasminogen (PLG) activity was 51.4% of that of normal pooled plasma (reference interval 70-130%) and the antigen level was 94.2% of that of normal pooled plasma (reference interval 80-150%). Nucleotide sequencing revealed a heterozygous G to A transition in exon 18, which resulted in an amino acid substitution of G732R. Both the proband's father and paternal grandfather were heterozygous for this mutation. Interestingly, the grandfather was found to be a compound heterozygote for plasminogen Kanagawa-I and Tochigi (A601T), so that his plasminogen activity and antigen level was 7.7% and 87.2% of that of normal pooled plasma, respectively. However, he has never been affected by significant thrombosis.

cDNA cloning of mouse BLM gene, the homologue to human Bloom's syndrome gene, which is highly expressed in the testis at the mRNA level

We cloned a cDNA encoding the mouse homologue to human Bloom's syndrome gene (BLM). The deduced amino acid sequence of mouse Blm showed 76% identity to the human sequence with very high homology in seven consecutive domains characteristic of DNA and RNA helicases. The expression of mBLM mRNA was examined in various tissues. Extremely high expression was observed in the testis as compared with other tissues. The mBLM mRNA level in the testis began to increase 12-14 days after birth, corresponding to the appearance of cells in the pachytene phase.

[Measurement of fibrinogen binding to platelets by flow cytometry: evaluation method for reflecting platelet activation]

Platelet aggregation, induced by agonist-mediated activation of membrane glycoprotein (GP) IIb/IIIa, and binding of fibrinogen to GPIIb/IIIa, is commonly analyzed using an aggregometer in the clinical laboratories. However, this method has a limitation to get precise results on the samples with small number of platelet (less than 100,000/1) or hyperlipidemia. Recently, flow cytometry has been used to evaluate platelet function due to the detection of fibrinogen binding to activated platelets using fluorescence labeled fibrinogen or anti-fibrinogen antibody. However, the appropriate rule for evaluation of the results has not been established yet. We converted a ratio of fibrinogen binding platelets to a velocity per unit concentration of ADP as follows: a difference of two ratios of fibrinogen binding platelets on neighboring two ADP concentrations was divided by a difference of ADP concentrations. It was considered to be a mean velocity between the two ADP concentrations. We adopted the range of ADP concentration, which gave the maximum velocity, as an index of platelet activation. If the peak of maximum velocity move toward lower or higher ADP concentration, it means hyper- or hypoactivation of the platelets, respectively. The objectivity of this method may make it a useful technique for clinical examination of platelet function.

Depolarization-induced tyrosine phosphorylation of p130(cas)

KCl-treatment of PC12 cells induces depolarization of the plasma membrane and Ca2+ influx into the cells. We have previously shown that KCl induced tyrosine phosphorylation of cellular proteins of 120, 110, 68, 44, and 42 k, and that the 68 k protein was paxillin. In the present study, we found that the 120 k protein was a Crk-associated Src substrate, p130(cas). KCl-induced tyrosine phosphorylation of p130(cas) was not observed in EGTA-containing medium, suggesting that it was due to Ca2+ influx into the cells. Time course experiments showed that tyrosine phosphorylation of p130(cas) peaked at 5 min after stimulation and returned to the basal level at 60 min, while mobility shift of p130(cas) was observed within 2 min and lasted over 60 min, indicating that serine or threonine residues, in addition to tyrosine, were phosphorylated on KCl stimulation. In vitro kinase assay of immunoprecipitates with anti-p130(cas) antibody suggested that some protein-tyrosine kinases were associated with p130(cas). Using the substrate region of p130(cas) as the substrate, we found that Fyn and Src were activated on stimulation with KCl. These results indicate that tyrosine phosphorylation of p130(cas) may be involved in Ca2+-dependent events in neuronal and neuroendocrine cells.

[Differentiation of selected abnormal hemoglobin by PCR-RFLP method]

Abnormal hemoglobin is one of the most frequent genetic disorder, of which about 700 variants have been reported in the world. Some abnormal hemoglobins such as HbS and HbC are endemic among limited human populations. We have found five subjects with abnormal hemoglobin in routine hematology analysis using an automated system Sysmex NE-7000. We isolated genomic DNA from the peripheral blood leukocyte of each subject, and amplified a 558 bp fragment of DNA including the entire exons 1 and 2 as well as intron 1 of the beta-globin gene. The amplified DNA fragments were subjected to direct sequencing by the dideoxy termination method on an automated DNA sequencer. The sequence analysis showed the abnormalities including HbA/C, HbS/C, HbE/E, and HbA/G-Szuhu. In the present study, we report a simple method for the mutual differentiation of these abnormal hemoglobins using restriction fragment length polymorphism (PCR-RFLP) method. Digestion of the amplified fragments described above with a restriction enzyme MnlI gave different RFLP patterns for HbA, HbC or S, HbE, and for HbG-Szuhu. RFLP using another enzyme, DdeI, could distinguish for HbS from HbC.

Megakaryocytes derived from CD34-positive cord blood cells produce interleukin-8

In a serum-free liquid culture, thrombopoietin (TPO) selectively stimulated the growth of megakaryocytic cells from CD34-positive cord blood cells. Using these cultured cells, we investigated cytokine production by human megakaryocytes. Day 10 megakaryocytes (2 x 10(5)) secreted > 1000 pg/ml of interleukin (IL)-8, in contrast to small amounts of IL-1beta and IL-6. A time-course study showed that the IL-8 production of megakaryocytes occurred at the late phase of the culture period. The megakaryocyte-conditioned medium had the chemotactic potential of polymorphonuclear leucocytes, which was abrogated by the addition of anti-IL-8 antibody, suggesting the secretion of biologically active IL-8. The combination of TPO and IL-1alpha was required for a significant augmentation of the IL-8 secretion. Direct evidence for IL-8 synthesis in megakaryocytes was provided by reverse transcription-polymerase chain reaction on purified CD41b+ cells and by the detection of intracellular IL-8 in CD41b+ cells. These results suggest that TPO stimulates not only the proliferation and differentiation of the progenitors capable of megakaryocytic lineage expression but also IL-8 release by the megakaryocytic cells with the aid of IL-1.

Severely impaired polymerization of recombinant fibrinogen gamma-364 Asp --> His, the substitution discovered in a heterozygous individual

During blood coagulation, soluble fibrinogen is converted to fibrin monomers that polymerize to form an insoluble clot. Polymerization has been described as a two-step process: the formation of double-stranded protofibrils and the subsequent lateral aggregation of protofibrils into fibers. Previous studies have shown that gamma chain residues Tyr-363 and Asp-364 have a significant role in polymerization, most likely in protofibril formation. To better define the role of these residues, we synthesized three fibrinogens with single substitutions at these two positions: Tyr-363 --> Ala, Asp-364 --> Ala, and Asp-364 --> His. We found that the release of fibrinopeptides A and B was the same for these variants and normal recombinant fibrinogen, showing that all variants had normal fibrin formation. In contrast, we found that polymerization was significantly delayed for both Ala variants and was almost nonexistent for the His variant. Clottability for the Ala variants was only slightly reduced, and fibrin gels were formed. Surprisingly, clottability of the His variant was substantially reduced, and fibrin gels were not formed. Our data suggest that both protofibril formation and lateral aggregation were altered by these substitutions, indicating that the C-terminal domain of the gamma chain has a role in both polymerization steps.

[Determination of neutrophil function by measuring superoxide production with whole blood flow cytometry]

The function of neutrophil can be evaluated by measuring oxidative metabolism using chemiluminescence, tetrazolium dye reduction or the others. Those results are not always satisfactory which would be caused by subtle difference in each preparation of the reagents and the lack of reproducibility. Recently, flow cytometric procedures for semi-quantitating superoxide production in neutrophils have been developed to evaluate their function. This procedure, which requires only small amount of whole blood, can easily and rapidly yield reproducible and reliable data. In this study, we optimized analytical conditions and then determined reference interval to evaluate neutrophil function of patients with various disorders. Optimal concentrations and incubation times of DCFH-DA and PMA were 5 mumol/l for 15 minutes and 25 micrograms/ml for 20 minutes, respectively. Production of superoxide in neutrophil was represented by relative fluorescence intensity(RFI) with assay coefficient of variance(CV) of 4.0-11.1%. Neutrophils had to be examined within 2 hours after venipuncture to obtain reliable data. Reference interval was determined as 170.4 +/- 58.7(mean +/- SD) RFI. Neutrophil function of patients with neutropenia, paroxysmal nocturnal hemoglobinuria(PNH), renal failure, systemic lupus erythematosus(SLE), myeloperoxidase deficiency, myelodysplastic syndrome(MDS), and diabetes mellitus were within the reference interval as evaluated by this method. Only neutrophils of chronic granulomatous disease, which is known to give clearly low superoxide production, showed actually decreased value. These results indicate that this procedure would be clinically useful for diagnosis of patient with impaired neutrophil function.

PCTAIRE 2, a Cdc2-related serine/threonine kinase, is predominantly expressed in terminally differentiated neurons

PCTAIRE are members of a subfamily of Cdc2-related kinases that have been shown to be preferentially expressed in post-mitotic cells. To examine the neural functions of PCTAIRE, rat cDNA clones encoding PCTAIRE 1, 2, and 3 were isolated, and their expression patterns in the brain were analyzed. Among the three rat PCTAIREs, only PCTAIRE 2 was found to be specifically expressed in the brain. Furthermore, its expression was transiently increased during brain development, peaking 7-15 days after birth. Within the brain, PCTAIRE 2 was concentrated in the neuronal layers of the hippocampus and olfactory bulb, which mostly consist of post-mitotic neurons. In an immunocytochemical experiment, immunoreactivity for PCTAIRE 2 was detected in the cell bodies and extended neurites of neurons, but not in astrocytes. The PCTAIRE 2 protein was recovered in the particulate fraction and resistant to solubilization with non-ionic detergent, suggesting that PCTAIRE 2 might be present as a component of a large protein complex. An immunoprecipitation assay revealed that the PCTAIRE 2 was associated with Ser/Thr-phosphorylating activity for histone H1, and that its activity depended on association with a regulatory partner that can be released under high-salt conditions. These findings suggest that PCTAIRE 2 is a Ser/Thr kinase that might play a unique role in terminally differentiated neurons.

Characterization of hypertriglyceridemia induced by L-asparaginase therapy for acute lymphoblastic leukemia and malignant lymphoma

Plasma lipids and apolipoproteins were determined in 19 children with acute lymphoblastic leukemia (ALL) or malignant lymphoma (ML) who were treated by L-asparaginase with prednisolone and vincristine. Extreme hypertriglyceridemia, i.e., over 10,000 mg/l of the maximum serum triglyceride concentration, was induced in 8 patients; these concentrations were not over 10,000 mg/l in the remaining 11 patients. The possibility was raised that the apolipoprotein E (apoE) isoform apoE4 (epsilon 4) participated in the induction of extreme hypertriglyceridemia, since the frequency of the apoE4/E3 phenotype in the patients with extreme hypertriglyceridemia was higher compared to those in the patients without extreme hypertriglyceridemia and control subjects (n = 248). The acute and severe hypertriglyceridemia was induced at 8 to 14 days after the end of the L-asparaginase therapy, with an earlier remarkable increase in the apoCIII/apoCII ratio and an extreme decrease of fibrinogen concentrations (a marker of the protein productivity of the liver). It is well known that apoCII and apoCIII have possible functions as an activator and an inhibitor of lipoprotein lipase (LPL), respectively. The extreme increase in the apoCIII/apoCII ratio could be one of the reasons for the accumulation of triglyceride-rich lipoproteins in plasma.

Activation of pp60c-src depending on cell density in PC12h cells

The Src family tyrosine kinases and their substrates are involved in cell-cell and cell-matrix interactions. We found that in PC12h cells, an increase of cell density enhanced the tyrosine phosphorylation levels of several intracellular proteins including p130(cas). Because it is a possible substrate for Src family kinases, we measured pp60(c-src) activity and found that it was higher in high density cultures than in low density cultures. This phenomenon was also observed in PC12 (the parental cell line of the PC12h subclone), Balb/c 3T3, Swiss 3T3, and Hela cells. One of the possible mechanisms regulating the kinase activity of pp60(c-src) is the phosphorylation and dephosphorylation of its negative regulatory site located at its C terminus. However, the tyrosine phosphorylation level of the regulatory site did not change depending on cell density. Subcellular fractionation showed that in high density culture, pp60(c-src) was translocated from detergent-soluble to detergent-insoluble fractions. These results suggest that cell-cell interaction might induce the activation of pp60(c-src) without changing its tyrosine phosphorylation levels.

DAP-1, a novel protein that interacts with the guanylate kinase-like domains of hDLG and PSD-95

BACKGROUND

The human homologue of the Drosophila discs large tumour suppressor protein (hDLG) and closely related proteins such as postsynaptic density protein 95 kDa (PSD-95) are associated with N-methyl-D-aspartate receptors (NMDA-R) and Shaker-type K+ channels, and are thought to be involved in their clustering.

RESULTS

We have identified a protein named DAP-1 that binds to the guanylate kinase-like domains of hDLG and PSD-95. DAP-1 was found to associate with hDLG, PSD-95, NMDA-R and adenomatous polyposis coli protein (APC). Furthermore, we found that DAP-1 is specifically expressed in the brain and colocalizes with PSD-95 and APC in mouse cerebellum. We also found that DAP-1 is colocalized with PSD-95 and NMDA-R at the synapses in cultured rat hippocampal neurons.

CONCLUSION

Our findings suggest that DAP-1 may play several roles in the molecular organization of synapses and neuronal cell signalling by interacting with hDLG and PSD-95, which in turn are associated with receptors, ion channels and APC.

Intrathoracic tracheal reconstruction with a collagen-conjugated prosthesis: evaluation of the efficacy of omental wrapping

Reconstructions of the intrathoracic trachea in 24 dogs were done with the use of 50 mm long collagen-conjugated tracheal prostheses. Omental wrapping was also done in 14 of the dogs (omentopexy group) to evaluate the efficacy of this option in comparison with results in the other 10 dogs (control group). All 24 dogs had uneventful postoperative courses and were killed at 4 weeks or 3, 6, or 12 months after the operation. Better epithelialization and fewer complications, such as mesh exposure and luminal stenosis, were observed in the omentopexy group than in the control group. Angiography and analysis of regenerated blood vessels revealed that vessel ingrowth had started within 4 weeks and that vessel formation reached its maximal point within 6 to 12 months in the omentopexy group. In contrast, revascularization of the subepithelial region in the control group was poor even after 3 months, and vessel formation continued for as long as 12 months. The differences between the two groups were considered to be mainly a result of the speed of blood vessel ingrowth into the regenerated mucosa. We conclude that our prosthesis can be used safely for intrathoracic tracheal reconstruction and that omental wrapping is a useful supplementary method that reduces the occurrence of complications.

Intra- and interbreed genetic variations of mitochondrial DNA major non-coding regions in Japanese native dog breeds (Canis familiaris)

Mitochondrial DNA (mtDNA) major non-coding regions were amplified from 73 dogs of eight Japanese native dog breeds and from 21 dogs of 16 non-Japanese dog breeds by the polymerase chain reaction and their DNA sequences were determined. A total of 51 nucleotide positions within the non-coding region (969-972 base pairs) showed nucleotide variations of which 48 were caused by transition. These nucleotide substitutions were abundant in the region proximate to tRNA(Pro). In addition to the nucleotide substitutions, the dog mtDNA D-loop sequences had a heteroplasmic repetitive sequence (TACACGTAGCG) involving size variation. The DNA sequences of the non-coding region were classified into four different groups by phylogenetic analysis and the deepest branchpoints of this dog phylogeny was calculated to about 100,000 years before the present. Phylogenetic analysis showed that Japanese native dog breeds could not be clearly delimited as distinct breeds. Many haplotypes found in members of some clustering groups were seen in each dog breed, and interbreed nucleotide differences between Japanese dog breeds were almost the same as the intrabreed nucleotide diversities.

Fibrinogen Matsumoto II: gamma 308 Asn-->Lys (AAT-->AAG) mutation associated with bleeding tendency

Fibrinogen Matsumoto II is a hereditary dysfibrinogenaemia identified in a woman with Basedow's disease and a bleeding tendency. Coagulation tests of the patient's plasma revealed a prolonged thrombin time and a decreased fibrinogen level determined by functional method. Release of fibrinopeptide A and B was normal, whereas fibrin monomer polymerization was delayed. Fibrinogen gamma-chain gene of the propositus was heterozygous for a missense mutation that resulted in Asn-->Lys substitution at codon 308. Though the same amino acid substitution was also attributed to fibrinogen Kyoto I and Bicetre II, fibrinogen Matsumoto II showed different clinical manifestations from them.

[Comparison of coagulation screening test results in two cases having dysfibrinogen]

We compared coagulation screening test [prothrombin time (PT), activated partial prothrombin time (APTT), fibrinogen level determined by thrombin time method] results in two cases of dysfibrinogenemia which were named Matsumoto I (MI) and II (MII), respectively. Amino acid substitution in MI, gamma 364Asp-->His, and that in MII, gamma 308 Asn-->Lys, were deduced by sequencing analysis of PCR amplified products from each genomic DNA. The ratios of functional fibrinogen levels determined by the thrombin time method to immunological levels determined by the latex photometric assay were markedly decreased in both cases. Thrombin time (TT) in the absence of Ca2+ and fibrin aggregation test were also decreased. It was noted that the above described abnormalities were more prominent in MI than MII. We thought these results reflected the extent of abnormality in fibrin monomer polymerization. Furthermore, the mutation at residue gamma 364Asp in MI is adjacent to the gamma 363Tyr which is within the primary polymerization site of fibrin monomer, whereas the mutation at the residue gamma 308Asn in MII is outside the primary site. Since fibrin monomer polymerization is promoted in lower ionic strength and in higher concentration of Ca2+, the data of PT, APTT, and TT, that were tested in the presence of higher concentration of Ca2+ and fibrin monomer, were similar in MI and MII. In addition, it would be speculated that mutant fibrinogen interferes the function of normal fibrinogen existed in heterozygous dysfibrinogenemia.