Protein C Deficiency Research Articles

Unraveling the Molecular Pathogenesis of Protein C Deficiency-Associated VTE: Insights from Protein C Mutations C238G and R189W in Thai Patients.

Protein C (PC) deficiency is a well-established risk factor for thromboembolism (TE), commonly manifesting in pediatric patients. This study aimed to elucidate the pathogenic mechanisms of two novel PC mutations, C238G and R189W, identified in Thai children with both venous and arterial TE. The effects of wild-type (WT), C238G, and R189W PC variants were investigated through transient transfection of HEK293T cells. PC secretion levels were measured, and immunofluorescence analysis was performed to assess intracellular localization. ER stress-related gene expression and UPR activation were evaluated. Structural analysis was conducted to explore the significance of the C238 and R189W residue in PC functionality. The C238G mutation led to a severe 95% reduction in PC secretion, while R189W showed a 30% decrease compared with WT. Immunofluorescence revealed that C238G-PC was predominantly retained in the ER, indicating protein misfolding. C238G-expressing cells exhibited significant upregulation of ER stress-related genes and UPR activation. In contrast, R189W resulted in only a modest increase in UPR gene expression, suggesting a less pronounced impact on protein folding and secretion. Structural analysis demonstrated the critical role of the C238 residue in maintaining PC's disulfide bond and overall conformation. This study reveals distinct molecular mechanisms by which the C238G and R189W mutations contribute to PC deficiency and increased thrombotic risk. The findings emphasize the essential role of the C238 residue in preserving PC structure and secretion, enhancing the understanding of PC deficiency-associated TE in pediatric patients.

Venous thromboembolism risk in adults with hereditary thrombophilia: a systematic review and meta-analysis.

This systematic review and meta-analysis assesses venous thromboembolism (VTE) risk in adults with hereditary thrombophilia, including Factor V Leiden (FVL) mutation, prothrombin G20210A (FII) mutation, compound heterozygosity, protein C (PC), protein S (PS), and antithrombin (AT) deficiency. Eligibility criteria included studies suitable for quantitative synthesis with extractable information on VTE risk in adults (> 15 years). There were no restrictions on VTE type, location, or occurrence. Two authors reviewed all studies and extracted data from 107 publications, encompassing 107,130 individuals (21,560 experiencing VTE). We used a random effects model and calculated odds ratios (ORs) with 95% confidence intervals (CIs). The highest risk was associated with homozygous FVL (OR 5.58, 95% CI 4.61-6.74), homozygous FII (OR 5.16, 95% CI 3.12-8.52), and compound heterozygosity (OR 4.64, 95% CI 2.25-9.58). In contrast, VTE risk was lowest for FVL heterozygosity (OR 2.97, 95% CI 2.41-3.67) and FII heterozygosity (OR 2.21, 95% CI 1.70-2.87), whereas PC (OR 3.23, 95% CI 2.05-5.08), PS (OR 3.01, 95% CI 2.26-4.02), and AT deficiency (OR 4.01, 95% CI 2.50-6.44) demonstrated an intermediate VTE risk. These results highlight an increased risk of venous thromboembolism in adults with hereditary thrombophilia. However, the risk for patients with PC, PS, and AT deficiency appears to be lower than previously stated, likely due to varying thrombogeneity of the underlying genetic mutations. Further research addressing this aspect of VTE risk in hereditary thrombophilia is imperative to improve patient management. TRIAL REGISTRATION: PROSPERO registration number CRD42022376757.

Protein C deficiency with venous and arterial thromboembolic events

Protein C (PC) is a key component of the vitamin K-dependent coagulation pathway. It exerts anticoagulant effects by inactivating factors V and VIII. Acquired or inherited PC deficiency results in a prothrombotic state, with presentations varying from asymptomatic to venous thromboembolism. However, there has been an increasing number of reports linking PC deficiency to arterial thromboembolic events, such as myocardial infarction and ischemic stroke. This editorial focuses on the association between PC deficiency and thromboembolism, which may provide some insights for treatment strategy and scientific research.

Validation for the function of protein C in mouse models.

Protein C (PC) is an anticoagulant that is encoded by the PROC gene. Validation for the function of PC was carried out in mouse models. In this study, autosomal recessive PC deficiency (PCD) was selected as the target, and the specific mutation site was chromosome 2 2q13-q14, PROC c.1198G>A (p.Gly400Ser) which targets G399S (GGT to AGC) in mouse models. To investigate the role of hereditary PC in mice models, we used CRISPR/Cas9 gene editing technology to create a mouse model with a genetic PCD mutation. The two F0 generation positive mice produced using the CRISPR/Cas9 gene editing technique were chimeras, and the mice in F1 and F2 generations were heterozygous. There was no phenotype of spontaneous bleeding or thrombosis in the heterozygous mice, but some of them were blind. Blood routine results showed no significant difference between the heterozygous mice and wild-type mice (P>0.05). Prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT) were prolonged in the heterozygous mice, while the level of fibrinogen content (FIB) decreased, suggesting secondary consumptive coagulation disease. The protein C activity of heterozygous mice was significantly lower than that of wild-type mice (P<0.001), but there was no significant difference in protein C antigen levels (P>0.05). H&E staining showed steatosis and hydrodegeneration in the liver of heterozygous mice. Necrosis and exfoliated epithelial cells could be observed in renal tubule lumen, forming cell or granular tubules. Hemosiderin deposition was found in the spleen along with splenic hemorrhage. Immunohistochemistry demonstrated significant fibrin deposition in the liver, spleen, and kidney of heterozygous mice. In this study, heterozygotes of the mouse model with a PC mutation were obtained. The function of PC was then validated in a mouse model through genotype, phenotype, and PC function analysis.

Analysis of four hereditary protein C deficiencies associated with vascular thromboembolism.

To analyze the clinical features and gene mutations in four families with hereditary protein C (PC) deficiency and explore their association with vascular thromboembolism. The clinical data of four patients with PC deficiency were retrospectively analyzed. Venous blood samples were collected from the four affected patients and their family members, and relevant coagulation indexes and thrombin production and inhibition tests were performed. PCR was used to amplify and directly sequence the PROC gene of the probands. Software analysis was conducted to assess the conservativeness and pathogenicity of the mutated loci. Protein models were constructed to analyze the spatial structure before and after the mutation. Thrombin generation and inhibition assays demonstrated impaired anticoagulation in all four probands. Proband 1 and 4 presented clinically with pulmonary embolism and lower extremity deep vein thrombosis (DVT), Proband 2 with cerebral infarction, and Proband 3 with DVT. Genetic analysis revealed the presence of the following mutations: c.541T > G heterozygous missense mutation, c.577-579delAAG heterozygous deletion mutation, c.247-248insCT heterozygous insertion mutation, c.659G > A heterozygous missense mutation, and a new variant locus c.1146_1146delT heterozygous deletion mutation in the four probands, respectively. In particular, c.1146_1146delT heterozygous deletion mutations not reported previously. Conservativeness and pathogenicity analyses confirmed that most of these amino acid residues were conserved, and all the mutations were found to be pathogenic. Analysis of protein modeling revealed that these mutations induced structural alterations in the protein or led to the formation of truncated proteins. According to the American College of Medical Genetics and Genomics (ACMG) classification criteria and guidelines for genetic variants, c.1146_1146delT was rated as pathogenic (PVS1 + M2 + PM4 + PP1 + PP3 + PP4). The identified mutations are likely associated with decreased PC levels in each of the four families. The clinical manifestations of hereditary PC deficiency exhibit considerable diversity.

Thrombosis-related characteristics of pregnant women with antithrombin deficiency, protein C deficiency and protein S deficiency in Japan

Background We previously conducted a primary survey of pregnant women with hereditary thrombophilia based on national surveillance in Japan, but did not examine their thrombosis-related characteristics. Antithrombin (AT) deficiency, protein C (PC) deficiency and protein S (PS) deficiency are the major types of hereditary thrombophilia in Japan.MethodsWe examined their detailed information related to thrombosis, and evaluated peripartum outcomes in comparison with control data obtained from the Japan Society of Obstetrics and Gynecology.ResultsDefinite or probable AT deficiency, PC deficiency and PS deficiency were observed in 80, 50, and 317 pregnancies, respectively, from 2014 to 2018 in Japan, with prevalence rates among total deliveries of 0.011%, 0.007%, 0.044%. The number of pregnancies with AT, PC and PS deficiency might have been as many as 27, 17 and 108 every year if complete answers had been provided. In the peripartum period of current pregnancies, 27.5% of women with AT deficiency, 28.0% with PC deficiency and 13.2% with PS deficiency developed thrombosis (p < 0.001 vs. control). Pregnant women with AT and PC deficiency were more susceptible to thrombosis than those with PS deficiency (P < 0.01). Of the thromboses, 92.3% occurred during pregnancy, 62.8% at less than 15 gestational weeks. The earliest onset of thrombosis was 5 gestational weeks. Prophylactic anticoagulation significantly prevented the onset of both antepartum and postpartum thrombosis (p < 0.0001). The rate of recurrent pregnancy loss in women with low PC or PS activities was significantly higher than in controls (p < 0.0001); however, it is unknown whether recurrent pregnancy loss is related to hereditary PS deficiency. There seem to have been few serious maternal or fetal/neonatal complications due to placental insufficiency related to a hypercoagulable state other than growth restriction.ConclusionsThis survey revealed the thrombosis-related characteristics of pregnant women with hereditary thrombophilia in Japan. We suggest prophylactic anticoagulation to prevent maternal or fetal/neonatal complications.

Perioperative management for fracture in a child with homozygous congenital protein C deficiency

Congenital protein C (PC) deficiency is one type of hereditary thrombosis. Patients with hereditary thrombosis are at high risk for thrombosis in the perioperative period, but a standard management strategy has not been established. Here we report a case of perioperative management of a fracture in a child with homozygous congenital PC deficiency. The patient was a 3-year-old boy who was diagnosed with congenital PC deficiency at birth. He sustained a traumatic supracondylar fracture of the right humerus and underwent emergency surgery. To prepare for open surgery for fixation of the fracture, warfarin was discontinued, and an activated PC (APC) concentrate was used in combination with vitamin K antagonism. However, warfarin was administered during the scheduled nail extraction because the operation was minimally invasive. No thrombotic or bleeding complications occurred in either operation. In emergency surgery in patients with congenital PC deficiency, the combination of vitamin K and APC concentrate is considered a maintenance option for PC deficiency. Postoperative PT-INR control was difficult in our patient due to the administration of vitamin K and withdrawal of warfarin, and this issue must be addressed in the future. Further case experience is desirable to standardize perioperative management.

The clinical and genetic landscape of early-onset thrombophilia in Japan.

To determine the optimal management for early-onset thrombophilia (EOT), the genetic and clinical features of protein C (PC)-, protein S (PS)-, or antithrombin (AT)-deficient patients of ≤20years of age were studied in Japan. Clinical and genetic information of all genetically diagnosed cases was collected through the prospective, retrospective study, and literature review. One-hundred-one patients had PC (n=55), PS (n=29), or AT deficiency (n=18). One overlapping case had PC- and PS-monoallelic variant. Fifty-five PC-deficient patients (54%) had 26 monoallelic or 29 biallelic variant(s), and 29 (29%) PS-deficient patients had 20 monoallelic or nine biallelic variant(s). None of the patients had AT-biallelic variants. The frequent low-risk allele p.K193del (PC-Tottori) was found in five patients with monoallelic (19%) but not 29 with biallelic variant(s). The most common low-risk allele p.K196E (PS-Tokushima) was found in five with monoallelic (25%) and six with biallelic variant(s) (67%). One exceptional de novo PC variant was found in 32 families with EOT. Only five parents had a history of thromboembolism. Thrombosis concurrently developed in three mother-newborn pairs (two PC deficiency and one AT deficiency). The prospective cohort revealed the outcomes of 35 patients: three deaths with PC deficiency and 20 complication-free survivors. Neurological complications were more frequently found in patients with PC-biallelic variants than those with PC-, PS-, or AT-monoallelic variants (73% vs. 24%, p=.019). We demonstrate the need for elective screening for EOT targeting PC deficiency in Japan. Early prenatal diagnosis of PC deficiency in mother-infant pairs may prevent perinatal thrombosis in them.

Computational analysis of the functional and structural impact of the most deleterious missense mutations in the human Protein C.

Protein C (PC) is a vitamin K-dependent factor that plays a crucial role in controlling anticoagulant processes and acts as a cytoprotective agent to promote cell survival. Several mutations in human PC are associated with decreased protein production or altered protein structure, resulting in PC deficiency. In this study, we conducted a comprehensive analysis of nonsynonymous single nucleotide polymorphisms in human PC to prioritize and confirm the most high-risk mutations predicted to cause disease. Of the 340 missense mutations obtained from the NCBI database, only 26 were classified as high-risk mutations using various bioinformatic tools. Among these, we identified that 12 mutations reduced the stability of protein, and thereby had the greatest potential to disturb protein structure and function. Molecular dynamics simulations revealed moderate alterations in the structural stability, flexibility, and secondary structural organization of the serine protease domain of human PC for five missense mutations (L305R, W342C, G403R, V420E, and W444C) when compared to the native structure that could maybe influence its interaction with other molecules. Protein-protein interaction analyses demonstrated that the occurrence of these five mutations can affect the regular interaction between PC and activated factor V. Therefore, our findings assume that these mutants can be used in the identification and development of therapeutics for diseases associated with PC dysfunction, although assessment the effect of these mutations need to be proofed in in-vitro.

Risk Factors, Clinical Manifestations, Anticoagulation Duration, and Outcomes in Carriers of Severe Inherited Thrombophilia

Severe Inherited thrombophilia comprises deficiencies of antithrombin (AT), protein C (PC), and protein S (PS), while gain-of-function (GoF) variants include homozygosity for factor V Leiden (FVL) or prothrombin gene G20210A mutation (PGM), or double-heterozygosity. Persons with AT, Protein C, or S deficiencies have a heightened risk of developing thrombosis from a young age. Several family members are usually affected, and thrombosis may occur in unusual locations.Homozygote or double heterozygous of GoF variants may not have a family history of thrombosis, and the first thrombotic event may present later in life. The optimal duration and type of anticoagulation and their long-term outcomes for persons with severe thrombophilia require further investigation. This study aimed to compare risk factors, clinical manifestations, type and duration of anticoagulation and clinical outcomes between persons with AT, protein C, and S deficiencies and homozygote or double heterozygous persons with GoF variants. Retrospective evaluation of electronic medical records of persons with severe inherited thrombophilia referred to the Center for Blood Disorders at Weill Cornell Medicine-New York Presbyterian Hospital between January 2009 and December 2022. Severe deficiencies of AT, PC and PS were defined as (AT ≤ 60%, PC ≤ 50% and PS ≤ 40%). Results needed to be confimed in second testing in one month interval. Statistical analysis was performed using descriptive statistics, and chi-square test and Fisher's exact test were applied to compare variables between persons with AC deficiencies and GoF variants. 795 persons with inherited thrombophilia were identified, of those 671 were excluded as they had mild thrombophilia. Of the remaining 124 persons, 17 were eliminated due to absence of confirmatory results. A total of 107 persons were analyzed. There were 47 (44%) persons with anticoagulant deficiencies (AT, PC, and PS) and 60 (56%) homozygotes for FVL, PGM or double heterozygote. Mean age (SD) was 48 (13.6) and 49 (12.2) for anticoagulation deficiency and GoF mutation, respectively (Table 1). Overall risk factors for thrombosis were similar in both groups. A positive family history of thrombosis in a first-degree family member was higher in the anticoagulant deficient group (68%) compared to the GoF mutation (42%) (p=0.008). In addition, persons with anticoagulant deficiency had higher rates of thrombosis before 40 years of age compared to the GoF mutation group, 68% and 26%, respectively (p=0.031). The most frequent anticoagulant prescribed was a DOAC in both groups, with 38% and 30% used for the anticoagulation deficient group and GoF mutation group, respectively. The duration of anticoagulation was similar in both groups with most patients remaining on anticoagulation for more than one year (79% anticoagulant deficient group, 65% GoF mutation group) (p=0.3). Patients with AC deficiency had more recurrent thrombotic events while on anticoagulation compared to GoF variants (17% vs 6.7%) (Table 2). Our results indicate that patients with severe inherited thrombophilia either due to anticoagulant deficiencies or GoF mutations are likely to remain on anticoagulation for long durations and may have recurrent thrombosis despite therapeutic anticoagulation.

New plasma protein C and protein S concentrate: A synergy for therapeutic purposes.

Deficiencies of protein C (PC) or protein S (PS) are rare diseases, characterized by mutations in the PC or PS genes, which encode plasma serine proteases with anti-coagulant activity. Severe PC or PS deficiencies manifest in early life as neonatal purpura fulminans, a life-threatening heamorrhagic condition requiring immediate treatment. First-line treatment involves replacement therapy, followed by maintenance with anti-coagulants. Replacement therapy with specific protein concentrates is currently only limited to PC, and therefore, a PC + PS concentrate represents a useful addition to therapeutic options, particularly for severe PS deficiency. Further, the production of a PC + PS concentrate from unused plasma fractionation intermediates would impact favourably on manufacturing costs, and consequently therapy prices for patients and health systems. Several chromatographic runs were performed on the same unused plasma fractionation intermediates using different supports to obtain a PC/PS concentrate. The best chromatographic mediums were chosen, in terms of specific activity and recovery. A full process of purification including virus inactivation/removal and lyophilization steps was set up. The final freeze-dried product had a mean PC concentration of 47.75 IU/mL with 11% of PS, and a mean specific activity of 202.5 IU/mg protein, corresponding to over 12,000-fold purification from plasma. The development of a novel concentrated PC/PS mixture obtained from a waste fraction of other commercial products could be used for its potential therapeutic role in the management of neonatal purpura fulminans pathology.

Thrombophilia Screening in Autoimmune Hemolytic Anemia: A Single-Center Cross-Sectional Study

Background Autoimmune hemolytic anemia (AIHA) is characterized by an increased rate of thrombosis, whose predictors are not completely clarified, although an association with active hemolysis (i.e., LDH &amp;gt;1.5 x ULN), anemia severity and previous splenectomy has been reported. Moreover, antithrombotic prophylaxis and its duration are not standardized in this patient-population. The value of thrombophilia screening, including congenital and acquired abnormalities, has not been established yet. Aim To investigate the prevalence of inherited and acquired thrombophilia abnormalities in a cohort of AIHA patients with or without thrombosis. Methods AIHA patients followed from January 2019 until September 2022 at a tertiary hematologic center in Milan, have been systematically tested for Factor V Leiden (FVL) and prothrombin (FII) G20210A mutation, protein C (PC), protein S (PS), antithrombin (AT) levels, and the presence of antiphospholipid antibodies (APLA, i.e., lupus anticoagulant, LAC, anti-cardiolipin and anti-b2-glycoprotein-1). Patients' hematological characteristics, additional thrombotic risk factors, history of venous/arterial thrombosis before and after AIHA diagnosis, and anticoagulant and/or antiplatelet therapies were retrospectively recorded. Results As shown in table 1, 59% of 92 enrolled patients were female with a median age at diagnosis of 70.5 years (range 24-89), and were classified as warm AIHA (50%), cold agglutinin disease (31.5%), mixed/atypical AIHA (9.8%), and Evans syndrome (association of AIHA and other immune cytopenia, 8.7%). Thrombophilia screening resulted positive in 19 patients (20.7%) including FVL (1.1%), F II (1.1%), APLA (10.8%), PC deficiency (1.1%), PS deficiency (2.2%), AT deficiency (2.2%), and more than one abnormality (2.2%). Additional risk factors considered were thrombosis prior to AIHA diagnosis, reported in 6 patients (7%, 3 venous and 3 arterial), and associated conditions (29%), including autoimmune disease (N=17), lymphoproliferative disease (N=7), myeloproliferative neoplasm (N=1), and paroxysmal nocturnal hemoglobinuria (N=1). Furthermore, 97% of subjects presented at least one risk factor (i.e., diabetes, obesity, bed rest, etc.) in addition to AIHA. Twenty-seven patients (28%) received anticoagulant prophylaxis after AIHA diagnosis, mainly short-term for hemolysis (42%) or surgery of lower limb fractures (37%), and long-term for atrial fibrillation in 24%; 22% of patients were on antiplatelet prophylaxis, and 4 patients had been splenectomized. Since AIHA diagnosis, 26 patients (28%) experienced thrombosis (77% venous, 23% arterial), with 33 total events (3 patients had &amp;gt; 1 event). Median hemoglobin and LDH at thrombosis were 8.6 g/dL (2-11.7), and 374 U/L (129-1873) respectively, indicating active hemolysis. No relationship was found with inherited thrombophilia abnormalities (3 patients, 8% experienced thrombosis vs 7, 10.5% who did not), whilst a significant association was noted with APLA positivity (p&amp;lt;0.05). Two patients with APLA experienced more than 1 event, one had 1 venous and 1 arterial event. Conclusions Along with disease activity and Evans syndrome, positivity for APLA appears the main predictor of thrombosis in AIHA and is therefore worth of testing, whilst extensive thrombophilia screening encompassing inherited abnormalities appears less useful.

Evaluation of prothrombotic risk of two PROC hotspot mutations (Arg189Trp and Lys193del) in Chinese population: a retrospective study

BackgroundR189W and K193del of protein C (PC) were hotspot mutations in Chinese population with venous thromboembolism (VTE), but almost two-thirds of patients with above mutations coexisting with other genetically or aquiredly prothrombotic risk factors. The aim of this study is to clarify the independent contributions of R189W or K193del to VTE risk.Methods490 unrelated patients with a personal history of VTE and 410 healthy participants were enrolled in this study. Data of their demographics, family history, genetic and acquired thrombosis risk factors were collected and statistically analyzed.ResultsPC R189W and K193del were identified in 3/410 (0.7%) and 7/410 (1.7%) healthy controls, and in 27/490 (5.5%) and 43/490 (8.8%) patients with VTE, respectively. Notably, about 70% of these mutant carriers combined with other genetic or acquired thrombophilic factors. After adjustment for age, gender, other inherited and acquired risk factors, we demonstrated that R189W and K193del were associated with 5.781-fold and 4.365-fold increased risk of VTE, respectively, which were significantly lower than the prothrombotic risk of anticoagulant deficiencies induced from rare mutations. Independent R189W or K193del mutation was not associated with earlier first-onset age as well as higher recurrent rate of VTE. However, combination of other genetic or acquired thrombophilic factors had supra-additive effects on those consequences. The more additional risk factors the patients had, the younger first-onset ages and higher risk of recurrence would be.ConclusionsAs the most frequent mutations for PC deficiency in Chinese population, both R189W and K193del mutations had limited independent contributions to VTE development compared with other rare mutations in PROC gene, but may act in concert with other genetic defects or acquired thrombotic risk factors to produce the final severe phenotype.

Prothrombotic states in portal vein thrombosis and Budd-Chiari syndrome in India: A systematic review and meta-analysis.

Both Budd-Chiari syndrome (BCS) and portal vein thrombosis (PVT) have been linked to various prothrombotic (PT) conditions. The PT profile in Asians is different from the west and there are no nationwide epidemiological surveys from India. Hence, the present meta-analysis was aimed at analyzing the prevalence of acquired and hereditary thrombophilia among Indian patients with non-cirrhotic PVT and BCS. A comprehensive literature search of Embase, Medline and Scopus was conducted from January 2000 to February 2022 for studies evaluating the prevalence of various PT conditions in Indian patients with PVT and BCS. Pooled prevalence rates across studies were expressed with summative statistics. Thirty-five studies with 1005 PVT patients and 1391 BCS patients were included in the meta-analysis. At least one PT condition was seen in 46.2% (28.7-63.7) of the PVT patients and 44.9% (37.3-60.7) of the BCS patients. Multiple PT conditions were seen in 13.0% (4.2-21.8) of the PVT patients and 7.9% (3.5-12.4) of the BCS patients. Among PVT patients, hyperhomocysteinemia was the commonest prothrombotic condition (21.6%) followed by protein C (PC) deficiency (10.7%), Janus kinase 2(JAK-2) mutation (8.5%) and antiphospholipid antibodies (APLA) (7.5%). Among patients with BCS, PC deficiency was the commonest prothrombotic condition (10.6%) followed by methylenetetrahydrofolate reductase (MTHFR) mutation (9.8%), APLA (9.7%) and JAK-2 mutation (9.1%). The PT profile in Indian patients with abdominal vein thrombosis is different from that of the western data with a lower prevalence of PT conditions in patients with BCS.

Congenital thrombophilia in East-Asian venous thromboembolism population: a systematic review and meta-analysis

BackgroundVarious inherited traits contribute to the overall risk of venous thromboembolism (VTE). In addition, the epidemiology of thrombophilia in the East-Asian VTE population remains unclear; thus, we aimed to assess the proportion of hereditary thrombophilia via a meta-analysis. MethodsPublications from PubMed, EMBASE, web of science, and Cochrane before December 30, 2022, were searched. Studies from Japan, Korea, China, Hong Kong, Taiwan, Singapore, Thailand, Vietnam, Myanmar, and Cambodia were included. Congenital thrombophilia was described as diseases including protein C (PC) deficiency, protein S (PS) deficiency, antithrombin (AT) deficiency, factor (F)V Leiden (FVL), and prothrombin G20210A mutations. Studies were selected by 2 reviewers for methodological quality analysis. A random-effects model was used for the meta-analysis, assuming that estimated effects in the different studies are not identical. ResultsForty-four studies involving 6453 patients from 7 counties/regions were included in the meta-analysis. The prevalence of PC, PS, and AT deficiencies were 7.1%, 8.3%, and 3.8%, respectively. Among 2924 patients from 22 studies, 5 patients were carriers of FVL mutation. Among 2196 patients from 10 studies, 2 patients were carriers of prothrombin G20210A mutation in a Thailand study. ConclusionThe prevalence of PC, PS, and AT deficiencies was relatively high, while a much lower prevalence of FVL and prothrombin G20210A mutations were identified in East-Asian patients with VTE. Our data stress the relative higher prevalence of PC, PS, and AT deficiencies for thrombophilia in the East-Asian VTE population.

Molecular basis of inherited protein C deficiency results from genetic variations in the signal peptide and propeptide regions

BackgroundInherited protein C deficiency (PCD) caused by mutations in protein C (PC) gene (PROC) increases the risk of thrombosis. Missense mutations in PC’s signal peptide and propeptide have been reported in patients with PCD, but their pathogenic mechanisms, except mutations in R42 residue, remain unclear. ObjectivesTo investigate the pathogenic mechanisms of inherited PCD caused by 11 naturally occurring missense mutations in PC’s signal peptide and propeptide. MethodsUsing cell-based assays, we evaluated the impact of these mutations on various aspects such as activities and antigens of secreted PC, intracellular PC expression, subcellular localization of a reporter protein, and propeptide cleavage. Additionally, we investigated their effect on pre-messenger RNA (pre-mRNA) splicing using a minigene splicing assay. ResultsOur data revealed that certain missense mutations (L9P, R32C, R40C, R38W, and R42C) disrupted PC secretion by impeding cotranslational translocation to the endoplasmic reticulum or causing endoplasmic reticulum retention. Additionally, some mutations (R38W and R42L/H/S) resulted in abnormal propeptide cleavage. However, a few missense mutations (Q3P, W14G, and V26M) did not account for PCD. Using a minigene splicing assay, we observed that several variations (c.8A>C, c.76G>A, c.94C>T, and c.112C>T) increased the incidence of aberrant pre-mRNA splicing. ConclusionOur findings suggest that variations in PC’s signal peptide and propeptide have varying effects on the biological process of PC, including posttranscriptional pre-mRNA splicing, translation, and posttranslational processing. Additionally, a variation could affect the biological process of PC at multiple levels. Except for W14G, our results provide a clear understanding of the relationship between PROC genotype and inherited PCD.

Genetic predisposition to early-onset thrombophilia: a study on challenges in personalized medicine for mothers, infants, and children

The number of reports on genetic predisposition to pediatric thrombosis is increasing. The risk of thrombosis in childhood varies according to patient age, and the contribution of genetic predisposition also differs. The term early-onset thrombophilia, which occurs until the age of 20 years in patients with genetic diagnosis, was defined. Then, the registry in Japan was established. Further, publications were reviewed comprehensively, and results revealed the genetic and clinical characteristics of patients. Less than 60% of patients presented with protein C (PC) deficiency, and over half of them had PC-gene monoallelic variants. The number of patients with protein S or antithrombin deficiency increased with age. None of them were aged between 6 and 8 years. PC-Tottori and protein S-Tokushima, which are high-frequency and low-risk variants in Japanese, contributed to the development of thrombosis. However, PC-Tottori did not affect the development of severe PC deficiency. One exceptional de novo PC-deficient variant was identified in 32 EOT families, and thrombosis developed concurrently in three pairs of mothers-newborns. Appropriate EOT screening tests targeting PC deficiency are required to prevent maternal and neonatal thromboses.

Analysis of the molecular pathogenesis of hereditary protein C deficiency due to a p.Gly86Asp variant of the PROC gene

To explore the molecular pathogenesis of hereditary protein C (PC) deficiency due to a p.Gly86Asp variant of the PROC gene through in vitro expression experiment. Wild type and Gly86Asp mutant expression plasmids of PC were constructed and respectively transfected into HEK 293FT cells. Total RNA was extracted from the transfected cells, and the expression of PROC gene was determined by quantitative real-time PCR (qRT-PCR). PC antigen (PC:Ag) in the supernatant of cell culture and cell lysate was determined by enzyme-linked immunosorbent assay (ELISA), and the level of PC protein was detected by Western blotting. qRT-PCR has detected no significant difference in the transcription level of wild-type and mutant-type PC. Compared with the wild type, the level of mutant PC:Ag in the supernatant and cell lysate were 81.3%±2.6% and 110.0%±2.8%, respectively. No difference was detected in the molecular weight between the wild-type and mutant-type PC by Western blotting. The PC content of mutant type was higher than wild-type in cell lysate, while the opposite was found with the cell culture supernatant. The impaired secretion by mutant PC may be the molecular mechanism of PC deficiency caused by the p.Gly86Asp variant.

Term Infant with Bilateral Parenchymal Brain Hemorrhages.

Term Infant with Bilateral Parenchymal Brain Hemorrhages.

Detection of Unknown and Rare Pathogenic Variants in Antithrombin, Protein C and Protein S Deficiency Using High-Throughput Targeted Sequencing.

The deficiency of natural anticoagulants—antithrombin (AT), protein C (PC), and protein S (PS)—is a highly predisposing factor for thrombosis, which is still underdiagnosed at the genetic level. We aimed to establish and evaluate an optimal diagnostic approach based on a high-throughput sequencing platform suitable for testing a small number of genes. A fast, flexible, and efficient method involving automated amplicon library preparation and target sequencing on the Ion Torrent platform was optimized. The cohort consisted of a group of 31 unrelated patients selected for sequencing due to repeatedly low levels of one of the anticoagulant proteins (11 AT-deficient, 13 PC-deficient, and 7 PS-deficient patients). The overall mutation detection rate was 67.7%, highest in PC deficiency (76.9%), and six variants were newly detected—SERPINC1 c.398A > T (p.Gln133Leu), PROC c.450C > A (p.Tyr150Ter), c.715G > C (p.Gly239Arg) and c.866C > G (p.Pro289Arg), and PROS1 c.1468delA (p.Ile490fs) and c.1931T > A (p.Ile644Asn). Our data are consistent with those of previous studies, which mostly used time-consuming Sanger sequencing for genotyping, and the indication criteria for molecular genetic testing were adapted to this process in the past. Our promising results allow for a wider application of the described methodology in clinical practice, which will enable a suitable expansion of the group of indicated patients to include individuals with severe clinical findings of thrombosis at a young age. Moreover, this approach is flexible and applicable to other oligogenic panels.