Novel deep intronic mutation in the coagulation factor XIII a chain gene leading to unexpected RNA splicing in a patient with factor XIII deficiency.

BACKGROUND: Coagulation factor XIII (FXIII) plays an essential role in maintaining hemostasis by crosslinking fibrin. Deficiency in FXIII affects clot stability and increases the risk of severe bleeding. Congenital FXIII deficiency is a rare disease. Recently, we identified a Chinese family with FXIII deficiency and investigated the pathogenesis of congenital FXIII deficiency, contributing non-coding pathogenic variants. METHODS: We performed common tests, coding sequencing by targeted next-generation sequencing (NGS), whole-genome sequencing and splice-sites prediction algorithms. The pathogenesis was investigated via minigene and nonsense-mediated mRNA decay (NMD) by experiments in vitro. RESULTS: The proband is homozygote for a novel deep intronic c.799-12G > A mutation in the F13A1 gene. Through direct sequencing of the minigenes mRNA, we found 10 bases of intron 6 insert in the mRNA of mutant minigenes mRNA. The relative expression of EGFP-F13A1 was higher by suppression of NMD in vitro. Furthermore, we found the proband with enhanced thrombin generation (TG). CONCLUSION: We reported a novel deep intronic c.799-12G > A mutation of F13A1 which produced a new acceptor site and frame shifting during translation introducing a premature termination codon. Our results support the premature termination codon triggered NMD. We need to pay attention to the position of potential alterable splicing sites while counselling and genetic test. The finding of enhanced TG indicated that we should be aware of the risk of thrombosis in patients with FXIII deficiency during replacement therapy.

Common genetic risk factors for venous thrombosis in the Chinese population.

Venous thrombosis is a major medical disorder caused by both genetic and environmental factors. Little is known about the genetic background of venous thrombosis in the Chinese population. A total of 1,304 individuals diagnosed with a first venous thrombosis and 1,334 age- and sex-matched healthy participants were enrolled in this study. Resequencing of THBD (encoding thrombomodulin) in 60 individuals with venous thrombosis and 60 controls and a functional assay showed that a common variant, c.-151G>T (rs16984852), in the 5' UTR significantly reduced the gene expression and could cause a predisposition to venous thrombosis. Therefore, this variant was genotyped in a case-control study, and results indicated that heterozygotes had a 2.80-fold (95% confidence interval = 1.88-4.29) increased risk of venous thrombosis. The THBD c.-151G>T variant was further investigated in a family analysis involving 176 first-degree relatives from 38 index families. First-degree relatives with this variant had a 3.42-fold increased risk of venous thrombosis, and their probability of remaining thrombosis-free was significantly lower than that of relatives without the variant. In addition, five rare mutations that might be deleterious were also identified in thrombophilic individuals by sequencing. This study is the largest genetic investigation of venous thrombosis in the Chinese population. Further study on genetics of thrombosis should focus on resequencing of THBD and other hemostasis genes in different populations.

Molecular basis of protein S deficiency in China.

Protein S (ProS) is a physiological inhibitor of coagulation with an important function in the down-regulation of thrombin generation. ProS deficiency is a major risk factor for venous thrombosis. This study enrolled 40 ProS-deficient probands to investigate the molecular basis of hereditary ProS deficiency in Chinese patients. A mutation analysis was performed by resequencing the PROS1 gene. Large deletions were identified by multiplex ligation-dependent probe amplification (MLPA) analysis. A total of 20 different mutations, including 15 novel mutations, were identified in 21 of the 40 index probands. Small mutations were detected in 18 (45.0%) probands, and large deletions were found in 3 (7.5%) probands, leaving 19 (47.5%) patients without causative variants. To evaluate the functional consequences of 2 novel missense variants, ex vivo thrombin-generation assays, bioinformatics tools, and in vitro expression studies were employed. The p.Asn365Lys ProS variant was found to have moderately impaired secretion and reduced activated protein C cofactor activity. In contrast, the p.Pro410His mutant appeared to have severely impaired secretion but full anticoagulant activity. This study is the largest investigation of ProS deficiency in China and the first investigation of the influence of Type I ProS missense mutations on the global level of coagulation function. The p.K196E mutation, which is common in the neighboring Japanese population, was not found in our Chinese population, and null mutations were common in our Chinese population but not common in Japan. Further genetic analysis is warranted to understand the causes of ProS deficiency in patients without a genetic explanation.

Comparative analysis of Decitabine intensified BUCY2 and BUCY2 conditioning regimen for high-risk MDS patients undergoing allogeneic hematopoietic stem cell transplantation.

The optimal conditioning regimen for high-risk myelodysplastic syndrome (MDS) patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains elusive. This study aimed to explore the anti-leukemic efficacy and toxicity of Decitabine (Dec, 20 mg/m2/day, day -11 to -7) intensified BUCY2 vs. traditional regimen in high-risk MDS population. We retrospectively evaluated 93 consecutive high-risk MDS patients undergoing allo-HSCT in our institution, comparing discrepancies in clinical characteristics and outcomes between cases using Dec-intensified BUCY2 (n = 52) and traditional BUCY2 regimen (n = 41). Three-year cumulative incidence of relapse after Dec-intensified BUCY2 conditioning was remarkably lower than that of patients using BUCY2 regimen (20.2% vs. 39.0%, p = 0.034). Overall survival and disease-free survival at 3 years for Dec-intensified BUCY2 group were 70.2% and 64.9%, respectively, which were significantly improved when compared with BUCY2 group (51.1% and 43.9%, p = 0.031 and p = 0.027). Furthermore, overall survival and disease-free survival for MDS cases receiving cytoreduction therapy were dramatically better than patients in non-cytoreduction group (p = 0.041, p = 0.047). In summary, the Dec-intensified conditioning regimen could be effective and feasible, providing prominent recurrence control with moderate toxicity for high-risk MDS patients. These patients might also benefit from pre-transplant cytoreductive therapeutic schedules. Larger randomized controlled trials are still needed to further confirm these conclusions.

[A Propensity Score Matching Study of Autologous Hematopoietic Stem Cell Transplantation and New Drug Chemotherapy for Newly Diagnosed Multiple Myeloma].

OBJECTIVE: To compare the clinical efficacy, survival, and prognosis of autologous hematopoietic stem cell transplantation (ASCT) with new drug chemotherapy in the treatment of newly diagnosed multiple myeloma (NDMM) in the new drug era. METHODS: The clinical data of 149 patients with NDMM treated with new drug induction regimen in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2012 to December 2019 were retrospectively analyzed. Twenty-four patients who received ASCT were in ASCT group, and 125 patients who did not receive ASCT were in non-ASCT group. The median follow-up time was 43 (1-90) months. The propensity score matching (PSM) method was used to balance confounding factors, then depth of response, overall survival (OS), and progression-free survival (PFS) between the two groups were compared and subgroup analysis was performed. RESULTS: After matching, the covariates were balanced between the two groups. Fifty-one patients (15 cases in ASCT group and 36 cases in non-ASCT group) were included. ASCT patients had a better complete response (CR) rate than non-ASCT patients receiving maintenance therapy (93.3% vs 42.3%, P=0.004), while there were no statistical differences in deep response rate and overall response rate (ORR) between the two groups (93.3% vs 65.4%, P=0.103; 93.3% vs 96.2%, P=1.000). Before matching, the 3 and 5-year PFS rate and median PFS (mPFS) in ASCT group and non-ASCT group were [89.6% vs 66.5%, P=0.024; 69.8% vs 42.7%; non-response (NR) vs 51.0 months], and the 3 and 5-year OS rate and median OS (mOS) were (100% vs 70.6%, P=0.002; 92.3% vs 49.6%; NR vs 54.0 months). After matching, the 3 and 5-year PFS rate and mPFS in ASCT group and non-ASCT group were (83.6% vs 61.7%, P=0.182; 62.7% vs 45.7%; NR vs 51.0 months), the 3 and 5-year OS rate and mOS were (100% vs 65.6%, P=0.018; 88.9% vs 46.9%; NR vs 51.0 months). Subgroup analysis showed that patients with mSMART 3.0 high risk stratification, the 3-year PFS rate and mPFS in ASCT group and non-ASCT group were (83.3% vs 41.5%, P=0.091; NR vs 34.0 months), and the 3-year OS rate and mOS were (100% vs 41.5%, P=0.034; NR vs 34.0 months). Patients with mSMART 3.0 standard risk stratification, the 3-year PFS rate and OS rate in ASCT group and non-ASCT group were (83.3% vs 76.8%, P=0.672; 100% vs 87.2%, P=0.155). The 3-year PFS and OS rate in MM patients who achieved deep response within 3 months after transplantation compared with non-ASCT patients who achieved deep response after receiving maintenance therapy were (83.1% vs 56.7%, P=0.323; 100% vs 60.5%, P=0.042), and the 3-year PFS and OS rate in patients who achieved overall response in both groups were (83.1% vs 62.5%, P=0.433; 100% vs 68.1%, P=0.082). After matching, Cox multivariate regression analysis showed that mSMART 3.0 risk stratification and ASCT were independent prognostic factors for OS. CONCLUSION: In the new drug era, ASCT can increase CR rate and prolong OS of NDMM patients. ASCT patients who are mSMART 3.0 high risk stratification or achieved deep response within 3 months after transplantation have better OS than non-ASCT patients receiving new drug chemotherapy. ASCT and mSMART 3.0 risk stratification are independent prognostic factors for OS in NDMM patients.

[Research Advance of Immune Checkpoint Molecule TIGIT in Hematological Malignancies--Review].

TIGIT is an inhibitory receptor containing T cell immunoglobulin and immune receptor protein tyrosine inhibitory motif domain. It shows high expression level on the surface of immune cells in tumor patients and plays an inhibitory role by binding to corresponding ligands, CD155 and CD112. Studying the mechanism of inhibitory effect of TIGIT and the way to block it shows a great significance in the immunotherapy of tumor. In this review, the structure of TIGIT molecule and its inhibitory effect on immune cells(including NK cells and T cells) were introduced, the expression level and the newest research advance of TIGIT molecule in lymphoma,multiple myeloma,leukemia and myelodysplastic syndrome were reviewed and summarized briefly, so as to provide reference for the further study of TIGIT and the application of TIGIT inhibitors in hematological malignancies.

Rapid and efficient gene splicing using megaprimer-based protocol.

Megaprimer-based methodology has been widely applied in site-directed mutagenesis, but rarely used in gene splicing. In this article, we describe a modification of the megaprimer PCR method, which can efficiently create and amplify a specific ligated chimeric gene segment in a PCR reaction and under a common PCR program that is widely used by researchers. More importantly, this modified method for splicing two or more gene fragments together revealed the mechanism of the megaprimer PCR method, by elucidating the key factor in the megaprimer-based protocol. In this method, the denatured megaprimer divided into two strands. One strand was used as template DNA to regenerate megaprimer and the other strand was used as an oligonucleotide primer to create a ligated chimeric gene product. In this article, we detail the modified megaprimer protocol for creating and amplifying these chimeric gene products, including a specific protocol for large chimeric gene products. We also provide additional tips to increase specificity and efficiency of the protocols. In conclusion, the improved megaprimer PCR protocol is a simple, broadly applicable protocol for splicing two different gene fragments together without relying on restriction sites.

Recombinant Tissue Plasminogen Activator-conjugated Nanoparticles Effectively Targets Thrombolysis in a Rat Model of Middle Cerebral Artery Occlusion.

The efficacy and safety of recombinant tissue plasminogen activator (rtPA) need to be improved due to its low bioavailability and requirement of large dose administration. The purpose of this study was to develop a fibrin-targeted nanoparticle (NP) drug delivery system for thrombosis combination therapy. We conjugated rtPA to poly(ethylene glycol)- poly(e-caprolactone) (PEG-PCL) nanoparticles (rtPA-NP) and investigated its physicochemical characteristics such as particle size, zeta potential, enzyme activity of conjugated rtPA and its storage stability at 4°C. The thrombolytic activity of rtPA-NP was evaluated in vitro and in vivo as well as the half-life of rtPA-NP, the properties to fibrin targeting and its influences on systemic hemostasis in vivo. The results showed that rtPA-NP equivalent to 10% of a typical dose of rtPA could dissolve fibrin clots and were demonstrated to have a neuroprotective effect after focal cerebral ischemia as evidenced by decreased infarct volume and improved neurological deficit (P<0.001). RtPA-NP did not influence the in vivo hemostasis or coagulation system. The half-life of conjugated rtPA was shown to be approximately 18 times longer than that of free rtPA. These experiments suggested that rtPA-conjugated PEG-PCL nanoparticles might be a promising fibrin-targeted delivery system for a combination treatment of thrombosis.

Brain-derived neurotrophic factor promotes growth and migration of multiple myeloma cells.

The evolution of multiple myeloma (MM) depends on complex signals from the bone marrow microenvironment, which support proliferation and survival of malignant plasma cells. Previous study defined a brain-derived neurotrophic factor-tyrosine kinase receptor B (BDNF/TrkB) axis in myeloma and autocrine growth stimulation by BDNF in various tumor cells. We examined the biological effects of BDNF on MM cells. Using a reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry, we observed that both BDNF and its high-affinity receptor TrkB are expressed by MM cell lines (RPMI 8226, U266, and KM3) and primary MM cells. Functional studies revealed that BDNF was a potent growth factor for MM. BDNF (5-500 ng/mL) had strong proliferative effects on both MM cell lines and primary MM cells, shown by [(3)H]thymidine incorporation assay. BDNF (12.5-200 ng/mL) also induced migration of MM cells, as indicated by the Transwell migration assay. Together, our data indicate that BDNF is a potent myeloma growth and chemotactic factor and suggest that the BDNF/TrkB pathway is a potential therapeutic target in MM.

Brain-derived neurotrophic factor inducing angiogenesis through modulation of matrix-degrading proteases.

BACKGROUND: Recent studies have proved that brain-derived neurotrophic factor (BDNF) possesses angiogenic activity in vitro and in vivo. However, the proangiogenic mechanism of BDNF has not yet been provided with enough information. To explore the proangiogenic mechanism of BDNF, we investigated the effects of BDNF on extracellular proteolytic enzymes, including matrix metalloproteinases (MMPs) and serine proteases, particularly the urokinase-type plasminogen activator (uPA)-plasmin system in human umbilical vein endothelial cells (HUVECs) model. METHODS: Tube formation assay was performed in vitro to evaluate the effects of BDNF on angiogenesis. The HUVECs were treated with various concentrations of BDNF (25 - 400 ng/ml) for different (6 - 48 hours), reverse transcriptase-polymerase chain reaction (RT-PCR) was used to assay MMP-2, MMP-9, TIMP-1, and TIMP-2 mRNA in HUVECs, and the conditioned medium was analyzed for MMP and uPA activity by gelatin zymography and fibrin zymography, respectively. uPA, plasminogen activator inhibitor (PAI)-1, tissue inhibitors of metalloproteinase (TIMP)-1, and TIMP-2 were quantified by western blotting analysis. RESULTS: BDNF elicited robust and elongated angiogeneis in two-dimensional cultures of HUVECs in comparison with control. The stimulation of serum-starved HUVECs with BDNF caused obvious increase in MMP-2 and MMP-9 mRNA expression and induced the pro-MMP-2 and pro-MMP-9 activation without significant differences in proliferation. However, BDNF had no effect on TIMP-1 and TIMP-2 production. BDNF increased uPA and PAI-1 production in a dose-dependent manner. Maximal activation of uPA and PAI-1 expression in HUVECs was induced by 100 ng/ml BDNF, while effects of 200 ng/ml and 400 ng/ml BDNF were slightly reduced in comparison with with those of 100 ng/ml. Protease activity for uPA was also increased by BDNF in a dose-dependent manner. BDNF also stimulated uPA and PAI-1 production beyond that in control cultures in a time-dependent manner from 12 hours to 48 hours after BDNF treatment. CONCLUSIONS: BDNF stimulates MMP and uPA/PAI-1 proteolytic network in HUVECs, which may be important to the acquisition of proangiogenic potential.

[Role of MAPK signal transduction pathway phosphorylation induced by granulocyte-macrophage-colony stimulating factor in the proliferation of hormone-independent prostate cancer].

OBJECTIVE: To investigate the phosphorylation intensity of MAPK pathway molecular Erk1/2 and the proliferation of prostate cancer cell line PC-3M. METHODS: Flow cytometry and RT-PCR were employed to study the ratio of different cell cycles and phases, respectively, before and after GM-CSF stimulation. Erk1/2 phosphorylation intensity was examined by Western blot simultaneously. RESULTS: The rate of PC-3M cells at S and G2/M stages and the expression intensity of Ki-67 increased after GM-CSF incubation in a dose-dependent manner. The phosphorylation intensity of Erk1/2 increased remarkably after stimulation with GM-CSF. CONCLUSION: The intensification of Erk1/2 phosphorylation is one important molecular mechanism of the proliferation of hormone-independent prostate cancer.

Spatial transmission and meteorological determinants of tuberculosis incidence in Qinghai Province, China: a spatial clustering panel analysis.

BACKGROUND: Tuberculosis (TB) is the notifiable infectious disease with the second highest incidence in the Qinghai province, a province with poor primary health care infrastructure. Understanding the spatial distribution of TB and related environmental factors is necessary for developing effective strategies to control and further eliminate TB. METHODS: Our TB incidence data and meteorological data were extracted from the China Information System of Disease Control and Prevention and statistical yearbooks, respectively. We calculated the global and local Moran's I by using spatial autocorrelation analysis to detect the spatial clustering of TB incidence each year. A spatial panel data model was applied to examine the associations of meteorological factors with TB incidence after adjustment of spatial individual effects and spatial autocorrelation. RESULTS: The Local Moran's I method detected 11 counties with a significantly high-high spatial clustering (average annual incidence: 294/100 000) and 17 counties with a significantly low-low spatial clustering (average annual incidence: 68/100 000) of TB annual incidence within the examined five-year period; the global Moran's I values ranged from 0.40 to 0.58 (all P-values < 0.05). The TB incidence was positively associated with the temperature, precipitation, and wind speed (all P-values < 0.05), which were confirmed by the spatial panel data model. Each 10 °C, 2 cm, and 1 m/s increase in temperature, precipitation, and wind speed associated with 9 % and 3 % decrements and a 7 % increment in the TB incidence, respectively. CONCLUSIONS: High TB incidence areas were mainly concentrated in south-western Qinghai, while low TB incidence areas clustered in eastern and north-western Qinghai. Areas with low temperature and precipitation and with strong wind speeds tended to have higher TB incidences.

[Factor VII detection and its association with lipid in ischaemic heart disease].

OBJECTIVE: To study the variation and significance of plasma factor VII (FVII) in various types of ischemia heart disease (IHD) and discuss its relation with plasma lipid. METHODS: FVIIa was determined with one stage clotting assay using a recombinant soluble tissue factor (rsTF). FVIIc was measured with one stage clotting assay. FVIIag was quantified with enzyme-linked immunosorbent assay (ELISA). RESULTS: FVIIa in stable angina (SA), unstable angina (UA), old and acute myocardial infraction (OMI, AMI) patients were higher than that of a normal group with significant statistic differences between any two groups. FVIIag in UA, OMI and AMI were higher than that in SA and the normal group. There were positive correlations between FVIIa and serum triglycerides, FVIIa and FVIIc, FVIIc and FVIIag. CONCLUSIONS: There is more or less activation of extrinsic coagulation pathway in any kind of IHD. FVIIa is the risk factor in the development of IHD and more sensitive than FVIIc or FVIIag. FVIIa is higher in OMI which may be one of the risk factors of reinfarction. Serum triglyceride may indirectly lead to the pathologic process of IHD by increasing the level of FVIIa.

Phenotypic and genotypic characterization of four factor VII deficiency patients from central China.

Hereditary coagulation factor VII deficiency (FVIID) is a rare autosomal, recessive inherited hemorrhagic disorder related to a variety of mutations or polymorphisms throughout the factor VII (FVII) gene (F7). The aims of this study were to characterize the molecular defect of the F7 gene in four unrelated patients with FVIID and to find the genotype-phenotype correlation. All nine exons, exon-intron boundaries, and 5' and 3'-untranslated regions of the F7 gene were amplified by PCR and the purified PCR products were sequenced directly. Suspected mutations were confirmed by another PCR and sequencing of the opposite strand. Family studies were also performed. A total of five unique lesions were identified, including three missense mutations (c.384A>G, c.839A>C, c.1163T>G, predicting p.Tyr128Cys, p.Glu280Ala and p.Phe388Cys substitution, respectively) and two splice junction mutations (c.572-1G>A, c.681+1G>T), among which two (p.Glu280Ala, p.Phe388Cys) were novel. A previously reported mutation p.Tyr128Cys was seen in the homozygous state in two unrelated patients. The other two cases were both compound heterozygotes of a missense mutation and a splicing site mutation. Multiple sequence alignment using DNAMAN analysis showed that all the missense mutations were found in residues that highly conserved across species and vitamin K-dependent serine proteases. Online software Polyphen and SIFT were used to confirm the pathogenic of the missense mutation. p.Tyr128Cys seems to be a hotspot of the F7 gene in ethnic Han Chinese population.

Genetic analysis in Factor XI deficient patients from central China: identification of one novel and seven recurrent mutations.

Factor XI (FXI) deficiency is a rare bleeding disorder with a range of manifestations from asymptomatic to trauma related bleeding. To identify mutations in FXI-deficient patients and characterize the phenotype-genotype relationship, we studied six patients and their 18 family members in central China. Five patients were identified by presurgical or routine laboratory screening but had no bleeding symptoms. Only one patient exhibited excessive injury- and surgical-related bleeding. Eight mutations were detected, including five nonsense mutations (p.Tyr369*, p.Arg72*, p.Gln281*, p.Trp519*, and p.Trp246*), two missense mutations (p.Thr40Ile and p.Ala430Thr), and a 4-bp deletion in a splice site (c.1136-4delGTTG); one mutation was novel (p.Thr40Ile). In vitro, the p.Thr40Ile mutant protein exhibited impaired secretion and function. Five of the patients were homozygous or compound heterozygous, but only one nonsense mutation was found in Patient 2. In these patients, bleeding tendency was not correlated with FXI levels or with a single heterozygous mutation. Thrombin generation tests could not distinguish the bleeder from non-bleeders. In conclusion, we reported 8 mutations in the FXI gene (F11) leading to FXI deficiency. Moreover, the functional consequences of a novel mutation leading to FXI deficiency have been elucidated. More cases are needed to find any signature of founder effect in the Chinese population and its potential relationship with other Asian population.

Compound heterozygous protein C deficiency in a family with venous thrombosis: Identification and in vitro study of p.Asp297His and p.Val420Leu mutations.

Hereditary protein C deficiency (PCD) is an autosomal inherited disorder associated with high risk for venous thromboembolism (VTE). This study aimed to explore the functional consequences of two missense mutations, p.Asp297His and p.Val420Ile, responsible for type I/II PCD and recurrent deep vein thrombosis (DVT) in a Chinese family. The plasma protein C activities (PC:A) of the proband and his sister were reduced to 4% and 5% of normal activity. However, protein C antigen (PC:Ag) concentrations were not equally decreased, with levels of 90.5% and 88.7%, respectively. Two missense mutations p.Asp297His and p.Val420Leu were identified in the protein C gene (PROC). The PC:A and PC:Ag levels in heterozygous state for p.Asp297His were 66% and 64.8%, whereas in heterozygous state for p.Val420Leu, these levels were 67% and 145%, respectively. Wild type (WT) and two mutant PROC cDNA expression plasmids were constructed and transfected into HEK 293T cells. Western blot analysis revealed that both p.Asp297His and p.Val420Leu showed a normal intracellular protein level. The extracellular protein level and specific activity of p.Asp297His were equally reduced to 37.7 ± 4.3% and 22.1 ± 2.5%, respectively. Mutant p.Val420Leu showed a relatively higher PC:Ag level and undetectable PC:A. Immunofluorescence staining revealed that WT and p.Val420Leu proteins were largely co-localized with both the protein disulfide isomerase (PDI) and cis-Golgi Marker (GM130), while the PC p.Asp297His mutant protein was mainly co-localized with PDI and much less co-localized with GM130. The thrombosis symptom in this family was associated with the two missense mutations in the PROC gene.

Genetic analysis should be included in clinical practice when screening for antithrombin deficiency.

Antithrombin (AT) deficiency increases the risk of thrombosis. Current evidence shows that some SERPINC1 mutations responsible for antithrombin deficiency often present a slightly decreased or normal activity and therefore could not be detected by functional tests. This study was designed to compare activity assays and direct genetic analyses in identifying hereditary antithrombin deficiency. In total, 400 consecutive patients with venous thrombosis were enrolled. Functional assays showed that 16 of the 400 individuals had decreased antithrombin activity, and 14 of them were confirmed by genetic analysis. Of the remaining 384 patients, 95 individuals without a known risk factor and 95 individuals with predisposing factors were also selected for gene sequencing. Eight additional causative mutations were identified in nine individuals and they should also be considered as antithrombin deficiency. In addition, a recurrent mutation, p.Arg356_Phe361del, was characterised. The mutant appeared to have a partially impaired secretion and a reduction in functional activity by 50 %. This study indicated that including genetic analysis in screening tests for identifying antithrombin deficiency was essential. Specifically, a genetic analysis of SERPINC1 is strongly recommended when individuals experience unprovoked thrombotic diseases, even if the AT activities are normal.