Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein S is a protein C-dependent and independent inhibitor of the coagulation cascade. Deficiency of protein S is an established risk factor for venous thromboembolism. We have used a strategy of specific amplification of the coding regions and intron/exon boundaries of the active protein S gene (PROS1) and direct single-strand solid phase sequencing, to seek mutations in 35 individuals with phenotypic protein S deficiency. Nineteen point mutations (16 novel) in 19 probands (or relatives of probands) with venous thromboembolism are reported here. Fifteen of the 19 mutations were expected to be causal and included 10 missense mutations (Lys9Glu, Glu26Ala, Gly54Glu, Cys145Tyr, Cys200Ser, Ser283Pro, Gly340Asp, Cys408Ser, Ser460Pro, and Cys625Arg). Three of the 15 mutations resulted in premature stop codons (delete T 635 producing a stop codon at position 126, Lys368stop and Tyr595stop) and two were at intron/exon boundaries (+1 G to A in intron d and +3 A to C in intron j). Of the remaining four mutations, three were within intronic sequence and one was a silent mutation within the coding region and did not alter amino acid composition. In two of the 10 missense mutations, reduced plasma protein S activity compared with antigen level suggested the presence of variant (type II) protein S.
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PMID:Identification of 19 protein S gene mutations in patients with phenotypic protein S deficiency and thrombosis. Protein S Study Group. 894 54

We report a family with type I and type III protein S (PS) deficiency, which showed to be phenotypic variants of the same genetic disease. Direct sequencing analysis of the PROS1 gene was performed to establish the genotype. The ratio of protein C antigen and total PS antigen levels (protein C/S ratio) was used to classify subjects at risk of venous thromboembolism. All PS deficient subjects had increased protein C/S ratios as well as a novel PROS1 c.1113T-->GG frameshift mutation.
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PMID:Identification of a novel PROS1 c.1113T-->GG frameshift mutation in a family with mixed type I/type III protein S deficiency. 1688 60

Protein S (PS) is a member of the vitamin K-dependent protein family containing similar gamma-carboxyglutamic acid (Gla) domains, although only PS has a thrombin-sensitive region (TSR), which is located between the Gla domain and the first epidermal growth factor-like domain. In this study, a novel PROS1 mutation was identified at the last nucleotide in intron C (c.260-1G>A) in a patient suffering from recurrent deep vein thrombosis associated with PS deficiency. To investigate the molecular mechanisms of PS deficiency caused by the novel PROS1 mutation, we characterized the mutant mRNA, and the secretion and function of the mutant PS molecule associated with the mutation. RT-PCR was used to detect the aberrant mRNA in the patient's platelets, the amount of which was markedly reduced and lacked the region corresponding to exon 4 coding the TSR of the PS molecule. The recombinant mutant PS lacking the TSR (TSR-lack PS) showed a markedly reduced transient expression/secretion level, 37.9% of that of wild-type (WT) PS. Activated protein C (APC) cofactor activity assay showed that TSR-lack PS had no cofactor activity. Moreover, binding assays of monoclonal antibodies recognizing the PS Gla domain and the Gla residues indicated that the bindings of TSR-lack PS to both of these antibodies were clearly weaker than those of WT PS. These findings suggest that the novel mutation leading to the absence of the TSR not only affected the secretion of mutant PS, but was also responsible for impairment of the Gla domain conformation required for the gamma-carboxylation to express APC cofactor activity.
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PMID:A novel splice site mutation in intron C of PROS1 leads to markedly reduced mutant mRNA level, absence of thrombin-sensitive region, and impaired secretion and cofactor activity of mutant protein S. 2002 58

Deficiencies of natural anticoagulant proteins including antithrombin (AT), protein C (PC) and protein S (PS) are important causes of inherited thrombophilia. This study aimed to report on the practical experience gained in performing genetic analyses of a large cohort of patients with AT, PC and PS deficiencies and to relate this knowledge to clinical application. We genotyped a large cohort of 709 unrelated patients with AT (231), PC (234) and PS (244) deficiencies referred to us by physicians throughout Germany. Mutations were detected by direct sequencing and multiplex ligation-dependent probe amplification (MLPA). The highest mutation detection rate (MDR) was found for the SERPINC1 gene (83.5%), followed by the PROC (69%) and PROS1 (43%) genes. Even at AT activities close to the normal range (75%), the MDR was 70%. Contrastingly, for PC and PS deficiencies, the MDR dropped significantly and mildly lowered to subnormal values. At PS activities >55% for PS no mutations were detected. Mutation profiles of all three genes were similar with the highest prevalence for missense mutations (63-78%), followed by nonsense (7-11%), splice-site mutations (7-13%), small deletions (1-8%), small insertions/duplications (1-4%) and large deletions (3-6%). In conclusion, genetic testing is a useful diagnostic tool for diagnosing thrombophilia. Based on our data, genetic analysis for patients with AT deficiency is indicated for all subnormal activities. In contrast, genotyping is not advisable for PC activities >70% and for PS activities >55%.
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PMID:Deficiencies of antithrombin, protein C and protein S - practical experience in genetic analysis of a large patient cohort. 2262 91

As the understanding of the genetic basis of the inherited thrombophilias has increased over recent years, their routine diagnostic genetic analysis has also matured. This review considers methods used to test for the factor V (F5) Leiden mutation and prothrombin 20210A (F2 c.*97G>A) allele, and analysis of the SERPINC1, PROC, and PROS1 genes in cases of antithrombin, protein C (PC), and protein S (PS) deficiency, respectively. Issues relating to quality are explored, highlighting where analytical and sample handling errors may occur. Detection of the factor V Leiden mutation and the prothrombin c.*97G>A allele are best performed using real-time polymerase chain reaction analysis as this relatively simple technique allows their discrimination from rare variants of neighboring nucleotides; not possible using the more time-consuming restriction digestion assays. With the advent of low-cost and high-throughput sequence analysis, direct sequencing has become the first-line method to provide a definitive diagnosis of inherited, rather than acquired, deficiencies. Large cohort studies have shown that antithrombin and PC mutations are identified in between 61 and 87% of patients, whereas the detection rate in PS deficiency is substantially lower in around 40% of patients. Large gene deletions make up between 7 and 10% of PS and antithrombin mutations and only 1% of PC mutations, but it is suggested that dosage analysis techniques such as multiplex ligation-dependent probe amplification should be used for all three genes as part of routine analysis to ensure mutations are not missed. Best practice guidelines are available from EuroGentest covering a wide variety of the issues raised in this review and all laboratories should participate in appropriate external quality assurance schemes to ensure they continue to offer high quality service.
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PMID:Quality in molecular biology testing for inherited thrombophilia disorders. 2290 70

Thrombophilia that is common among Caucasians is caused by genetic polymorphisms of coagulation factor V Leiden (R506Q) and prothrombin G20210A. Unlike that in Caucasians, thrombophilia that is common in the Japanese and Chinese involve dysfunction of the activated protein C (APC) anticoagulant system caused by abnormal protein S and protein C molecules. Approximately 50% of Japanese and Chinese individuals who develop venous thrombosis have reduced activities of protein S. The abnormal sites causing the protein S molecule abnormalities are distributed throughout the protein S gene, PROS1. One of the most common abnormalities is protein S Tokushima (K155E), which accounts for about 30% of the protein S molecule abnormalities in the Japanese. Whether APC dysfunction occurs in other Asian countries is an important aspect of mapping thrombophilia among Asians. International surveys using an accurate assay system are needed to determine this.
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PMID:Activated protein C anticoagulant system dysfunction and thrombophilia in Asia. 2330 Dec 17

Genetic predisposition of thromboembolism depends on the racial background. Factor V Leiden (G1691A) and factor II mutation (G20210A) are the leading causes of inherited thrombophilias in Caucasians, but are not found in Asian ancestries. Protein S (PS), protein C (PC) and antithrombin (AT) activity are reportedly low in 65% of adult Japanese patients with deep vein thrombosis. Approximately half of the patients with each deficiency carry the heterozygous mutation of PS (PROS1; 20%), PC (PROC; 10%), and AT genes (SERPINC1: 5%). Recently, several studies have revealed an outline of inherited thrombophilias in Japanese children. Congenital thrombophilias in 48 patients less than age 20 years consisted of 45% PC deficiency, 15% PS deficiency and 10% AT deficiency, along with other causes. All PS- and AT-deficient patients had a heterozygous mutation of the respective gene. On the other hand, PC-deficient patients were considered to carry the homozygous or compound heterozygous mutation in 50%, the heterozygous mutation in 25%, and unknown causes in the remaining 25% of patients. Half of unrelated patients with homozygous or compound heterozygous PROC mutations carried PC-nagoya (1362delG), while their parents with its heterozygous mutation were asymptomatic. Most of the PC-deficient patients developed intracranial lesion and/or purpura fulminans within 2 weeks after birth. Non-inherited PC deficiency also conveyed thromboembolic events in early infancy. The molecular epidemiology of thrombosis in Asian children would provide a clue to establish the early intervention and optimal anticoagulant therapy in pediatric PC deficiency.
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PMID:Protein C deficiency as the major cause of thrombophilias in childhood. 2352 Oct 84

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.
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PMID:Molecular basis of protein S deficiency in China. 2381 90

Protein C (PC) and protein S (PS) are vitamin K-dependent glycoproteins, that act as natural anticoagulants. The proteolytic activation of PC by thrombin occurs on the surface of endothelial cells and involves thrombomodulin and endothelial PC receptor. In the presence of PS, phospholipids and calcium, activated PC (APC) inactivates membrane bound factors V (FVa) and FVIIIa by their cleavage at the specific arginine residues. PC and PS deficiencies are inherited as autosomal dominant disorders associated with recurrent venous thromboembolism (VTE) and, in most cases, derived from heterozygous missense mutations (78% and 63%, respectively). Heterozygous PC deficiency is found in 6% of families with inherited thrombophilia, in 3% of patients with a first-time deep vein thrombosis (DVT) and 0.2-0.3% of healthy individuals. The PS deficiency is detected more commonly than PC deficiency and its prevalence has been estimated with a less than 0.5% in the general European population and 2% to 12% of selected groups of thrombophilic patients. Approximately 75% of PC-deficient patients have type I deficiency and 95% of PS-deficient patients develop type I and type III of PS deficiency. The diagnosis of PC and PS deficiencies is challenging, many preanalytical and analytical factors may affect the PC/PS levels. Molecular analysis of the PC and PS genes (PROC and PROS1, respectively) involves direct gene sequencing and if negative, multiplex ligation-dependent probe amplification (MLPA) method. Patients with low PC and PS levels and the known mutation within PROC or PROS1 genes combined with other genetic or environmental thrombosis factors are at increased risk of recurrent thromboembolic events and require lifelong oral anticoagulation.
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PMID:Protein C and protein S deficiency - practical diagnostic issues. 2398 5

Hereditary natural anticoagulant deficiencies are the major cause of genetic thrombophilia in Asia. Given the growing acknowledgment of the risk of venous thromboembolism in Asian populations, we investigated the frequency and mutation spectrums of natural anticoagulant deficiency in Korea. The group of patients consisted of consecutive patients with venous thromboembolism screened for thrombophilia. Genetic tests were performed on suspicion of natural anticoagulant deficiency. For the population group, >3,000 individuals were screened from routine check-ups, and those with a low level (<1(st) percentile) of natural anticoagulant underwent genetic tests. Mutations were detected by direct sequencing of PROC, PROS1, and SERPINC1, followed by additional multiplex ligation-dependent probe amplification for PROS1 and SERPINC1 for dosage mutations. Among 500 patients screened, 127 were suspected of having a natural anticoagulant deficiency, and this was genetically confirmed in 71: protein C deficiency in 36 (50.7%), antithrombin deficiency in 21 (29.6%), and protein S deficiency in 14 (19.7%). Among 3,129 individuals from the population who were screened, the frequency of natural anticoagulant deficiency was ~1.0%: antithrombin deficiency 0.49%, protein C deficiency 0.35%, and protein S deficiency 0.16%. Two PROC mutations causing type I protein C deficiency were prevalent (Arg211Trp and Met406Ile in patients and Arg211Trp in the population). Two SERPINC1 mutations causing type II antithrombin deficiency, Arg79Cys and Ser158Pro, were prevalent in the population group. This is the first study on the genetic epidemiology of natural anticoagulant deficiencies in Korea. The results demonstrated that the frequencies and spectrum of mutations underlying genetic thrombophilia in Korea are different not only from those in Caucasians but also those in other Asian populations.
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PMID:Distinct frequencies and mutation spectrums of genetic thrombophilia in Korea in comparison with other Asian countries both in patients with thromboembolism and in the general population. 2459 56


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