scholarly journals Carbohydrate Glycosylation Deficiency Disorder Secondary to Absence of Phosphomannose Mutase Confers Both a Hemorrhagic and Thrombotic Phenotype

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4713-4713
Author(s):  
Katrina Gleditsch ◽  
Afshin Ameri
Keyword(s):  
Protein C ◽  
Conflicts Of Interest ◽  
Protein S ◽  
Factor Ix ◽  
Bleeding Complications ◽  
Factor Xi ◽  
Inherited Disorders ◽  
Surgical Interventions ◽  
Surgery Patient ◽  
Organ Systems

Abstract Congenital disorders of glycosylation are a group of inherited disorders affecting the addition of a carbohydrate moiety to a protein. A defect in this pathway can cause adverse effects in most organ systems, often presenting early in life. The most common of these disorders is CDG type 1a / PMM2-CDG). In this disorder the loss of the enzyme phosphomannomutase-2 prevents the conversion of mannose-6-phosphate to mannose-1-phosphate. This has previously been associated with deficiencies of protein C, protein S, antithrombin III, factor IX and factor XI and a subsequent imbalance of coagulation pathways leading to thrombotic events. We present the case of a 14-year-old male with known history of CDG1a and previous bleeding complications following left orchiopexy at age 3, at that time coagulation screening showed a normal PT/PTT and surgery was deemed safe. The patient now presented to our pediatric hematology/oncology clinic for further evaluation of coagulation abnormalities prior to pediatric surgery performing right orchiopexy. Laboratory values at this time showed coagulation deficiencies, of ATIII, Factor XI, Protein C and Protein S, PT/ PTT , F VIII, FIX and vWF where normal. Prior to surgery, patient was given fresh frozen plasma and ATIII concentrate the patient underwent a successful Stage One Fowler-Stephen Procedure with adequate hemostasis. Several months later the patient developed leg swelling and was diagnosed right femoral DVT. This resolved with ATIII substitution and anticoagulation with LMW heparin. The patient's immediate family was tested for bleeding/clotting disorders and results were found to be normal. This report not only supports the association of bleeding but also thrombosis with CDG1a. We propose that in patients with known CDG routine PT/PTT will not uncover a hemostatic abnormality but further screening isolated factor deficiency need to be performed and prophylactic factor substitution be performed prior to any surgical interventions. Also an awareness of the highly procoagulant state in these patients that predispose to DVT and central nervous system vascular thrombosis need to be present. Disclosures No relevant conflicts of interest to declare.

New Insights Into Factor XI Function: From Biochemistry to Animal Models

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. SCI-20-SCI-20
Author(s):  
David Gailani
Keyword(s):  
Animal Models ◽  
Arterial Thrombosis ◽  
Conflicts Of Interest ◽  
Thrombus Formation ◽  
Anticoagulation Therapy ◽  
Factor Ix ◽  
Bleeding Complications ◽  
Contact Activation ◽  
Factor Xi ◽  
Deficient Mice

Abstract Abstract SCI-20 Factor XI (fXI) is the zymogen of an enzyme (fXIa) that contributes to blood coagulation through activation of factor IX (fIX). FXI has structural and mechanistic features that distinguish it from the vitamin K-dependent proteases of coagulation. The protein is a dimer of identical 80 kDa subunits, each containing four apple domains (A1-A4) that form a platform at the base of the trypsin-like protease domain. The apple domains contain binding sites for fIX, platelet receptors, and high molecular weight kininogen. FXI is converted to fXIa by cleavage of a single bond on each subunit, unmasking exosites required for fIX binding. Conversion of fXI to fXIa proceeds through an intermediate with only one activated subunit (1/2-fXIa). 1/2-fXIa, and monomeric forms of fXIa, activate fIX in a manner similar to fully activated fXIa, indicating each subunit functions as a complete enzyme. The importance of the dimeric structure of fXI is not clear at this point. It may facilitate activation, or allow fXIa to bind simultaneously to fIX and a surface (a platelet for example) at a wound site. Congenital fXI deficiency is associated with a variable propensity to bleed excessively after trauma to certain tissues. Symptoms are usually milder than in fIX deficiency (hemophilia B), and many affected individuals are asymptomatic. In the cascade-waterfall model of coagulation, fXI is activated by factor XIIa (fXIIa) during a process called contact activation. However, current models often omit contact activation, because fXII deficiency is not associated with abnormal hemostasis. Thrombin activates fXI, providing an explanation for normal hemostasis in fXII deficiency. In contrast to its modest role in hemostasis, fXI may serve an important role in thromboembolic diseases. High fXI levels are a risk factor for arterial and venous thrombosis in humans; and deficiency or inhibition of fXI confers resistance to thrombosis in animal models. FXI deficient mice are as resistant to arterial thrombosis as fIX deficient mice, or wild type mice treated with a supra-therapeutic dose of heparin. In arterial thrombosis models in mice, rabbits and baboons, lack of fXI activity results in instability of platelet rich thrombi, preventing vessel occlusion. FXI deficiency also prolongs survival and lessens the severity of disseminated intravascular coagulation in a mouse polymicrobial sepsis model. Interestingly, mice with combined deficiencies of fXI and fIX are more resistant to arterial thrombus formation than mice deficient in only one of these proteins, indicating fXIa has proteolytic targets other than fIX. The observation that fXII deficient mice are resistant to arterial thrombosis suggests that activation of fXI by contact activation, while unnecessary for hemostasis, contributes to thrombin generation in some pathologic processes. If the observations in mice apply to thromboembolism in humans, then fXIa and/or fXIIa may be excellent targets for novel antithrombotic strategies. In contrast to drugs such as heparin and warfarin, agents targeting fXIa or fXIIa would likely be associated with relatively few bleeding complications, and could be employed in clinical situations where anticoagulation therapy is currently contraindicated. Disclosures: No relevant conflicts of interest to declare.

DEVELOPMENT OF A PROTEIN C CONCENTRATE

1987 ◽  
Author(s):  
Prabir Bhattacharya ◽  
Carolyn L Orthner ◽  
Dudley K Strickland
Keyword(s):  
Protein C ◽  
Antithrombin Iii ◽  
Activated Protein C ◽  
Protein S ◽  
Exchange Chromatography ◽  
Factor Ix ◽  
Human Protein ◽  
Red Cross ◽  
American Red Cross ◽  
Protein C Concentrate

A Protein C (PC) concentrate may be useful in treating patients with congenital or acquired Protein C deficiencies. A method for preparation of a human Protein C concentrate has been developed using a by-product of American Red Cross Factor IX production as the starting material (Menache et. al. Blood, 64, 1220). Levels of other vitamin K dependent proteins in the Protein C concentrate were measured and found to be <10 units per 100 units of PC, except for Protein S. The level of Protein S as judged by immunological assay was 30 u/100 u PC. Assay of the PC concentrate using chrcmogenic substrates revealed that levels of thrombin, Factor 3�a and Factor IXa were less than 0.006 u/mL. In addition, Antithrombin III and ax -macroglobulin were not detected. The vivo effects of Protein C concentrate and Protein C activated by thrombin have been tested in anesthetized rabbits. Thrombin was removed from the activated Protein C by ion-exchange chromatography; depletion was verified by S-2238 or by a clotting assay (< 0.006 u/mL). Rabbits were injected with Protein C concentrate (400 ug/kg) or activated Protein C 24 - 48 ug/Kg). The activated partial thromboplastin time (APTT), FactorV (FV) and Factor VIII (FVIII) levels were measured in samples collected over the next three hours. Infusion of PC concentrate elevated the level of PC to 150% of the preinfusion level within 30 min. It did not change the levels of FV, FVIII, fibrinogen or platelet count. In contrast, infusion of activated Protein C produced progressive prolongation of the APTT. Levels of FV and FVIII were decreased to 25% and 50% of preinfusion levels, respectivelv, three hours after the infusion. Fibrinogen and platelet levels were unchanged during that period. These data demonstrate that activated human Protein C concentrate induces an anticoagulant effect that can be readily measured in rabbits.

scholarly journals The Molecular Diagnosis of Patients with Vein Thrombosis Due to Deficiency of Inherited Anticoagulant Proteins

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1535-1535
Author(s):  
Rong-Fu Zhou ◽  
Bo Gao ◽  
Jian Ou-Yang
Keyword(s):  
Missense Mutation ◽  
Promoter Region ◽  
Protein C ◽  
Conflicts Of Interest ◽  
Genetic Diagnosis ◽  
Protein S ◽  
Deletion Mutation ◽  
Heterozygous Mutation ◽  
Homozygous Mutation ◽  
Thrombin Time

Abstract Objective: To make genetic diagnosis and pedigree analysis for patients with recurrent venous thromboembolism due to inherited deficiency of protein C (PC), protein S (PS). Methods: The routine coagulation tests including activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) were performed. Chromogenic substrate assay was used to detect the activities of Protein C (PC:C), total Protein S (PS:C) and antithrombin (AT:C). All exons and their flanks of PC and PS gene were amplified by polymerase chain reaction (PCR). The PCR products were sequenced directly and blastered to normal sequence of corresponding anti-coagulant protein to find the gene mutations. Results: Totally nine probands with DVT or PE were enrolled, their peripheral blood and medical histories collected after informed consents. Proband 1, 2 and 3 were with combined deficiency of PC and PS, while proband 4 was with PC deficiency. Sequencing of PC gene showed there were polymorphism sites G4880A, C4867T and A5054T in promoter region for all four probands with PC deficiency. PC:C and PS:C for proband 1 was 48% and 26.3%, respectively. PC gene sequencing showed that there was a heterozygous mutation A6578T in exon2 region, resulting in Thr18Ser. Sequencing of PS gene showed there was G68395T heterozygous mutation in exon4 region, leading to Arg90Leu. PC:C and PS:C of proband 2 was 27% and 22.9%, respectively. Heterozygous mutations of G68428A and C68430T in exon4 region of PS gene were found, leading to Arg100His and Gln101Stop, respectively. Proband 3 was with PC deficiency and PS deficiency, PC:C and PS:C were 58% and 57.3%. Heterozygous AGA12702-12704 or AGA12705-12707 deletion mutation was found in Exon2 of PC gene resulting in Arg192del or Arg193del, and heterozygous missense mutation A15240G in Exon9 resulting in His370Arg. Heterozygous mutation G68395T and G825512C was found in Exon4 and Exon9 region of PS gene, respectively, resulting in Arg90Leu and Ser321Thr. Proband 4 was with PC deficiency, PC:C50%. There was no other mutation detected except for polymorphism sites in promoter region. Proband 5 was with PS deficiency, PS:C 38.8%. Heterozygous mutation G68395T in exon4 region was detected, leading to Arg90Leu. Homozygous mutation C102102T was found in Exon14 region,leading to Gla616Val. Proband 6 was with PS deficiency, PS:C 35.2%. Heterozygous mutations G68395T andC68430T in Exon4 were found, leading to Arg90Leu and Gln101Stop, respectively. Proband 7 was with PS deficiency, PS:C 43.7%.Homozygous mutation C102102T in exon14 region was detected, resulting in Gla616Val. Proband 8 was with PS deficiency, PS:C43.6%. Heterozygous mutation G68395T and C68430T in exon4 region was found, leading to Arg90Leu and Gln101Stop. Proband 9 was with PS deficiency, PS:C 7.7%. Two of his family members were also with PS deficiency (II2，III2） with heterozygous mutation G68395T in Exon4 region（II1，II2，III1，III2）, leading to Arg90Leu. Conclusions: Polymorphisms of G4880A, C4867T and A5054T in promoter region, missense mutation A6578T, A15240G, AGA12702-12704 or 12705-12707 deletion mutation in PC gene，missense mutation G68395T, G68428A, C86066T, G82512C, C102102T, and nonsense mutation C68430T in PS gene might be the cause of reduced activities of corresponding anticoagulant proteins. All these mutations, except for C86066T in PS gene, which had been reported in Hongkong, are de novo ones. Disclosures No relevant conflicts of interest to declare.

ANTICOAGULANT AND ANTIGENIC LEVELS OF PROTEIN C AND PROTEIN S IN PATIENTS ON STABILIZED ORAL ANTICOAGULANT TREATMENT

1987 ◽  
Author(s):  
A D'Angelo ◽  
F Gilardoni ◽  
M P Seveso ◽  
P Poli ◽  
R Quintavalle ◽  
...  
Keyword(s):  
Vitamin K ◽  
Oral Anticoagulant ◽  
Protein C ◽  
Protein S ◽  
Reference Interval ◽  
Factor Ix ◽  
Activity Levels ◽  
Anticoagulant Treatment ◽  
Oral Anticoagulant Treatment ◽  
Congenital Deficiency

Isolated deficiencies of protein C and protein S, two vitamin K-dependent plasma proteins, constitute about 70% of the congenital abnormalities of blood coagulation observed in patients with recurrent venous thrombosis beLow the age of 40. The laboratory diagnosis of congenital deficiency of these proteins represents a major problem since a large proportion of patients are on oral anticoagulation (OA) at the time the deficiencies are suspected.Under these circumstances the availability of a reference interval obtained in patients on stabilized OA has proven useful.Functional (C) and antigenic levels (Ag) of protein C, protein S, factor IX and II were estimated in 136 patients on stabilized OA, subdivided according to the degree of anticoagulation (Internatio nal Normalized Ratio, INR).The results indicate that with increasing anticoagulation the activity levels of all the vitamin K-dependent factors decrease to a greater extent than the corresponding antigenic levels. At variance with the other factors, total protein S antigen levels are only moderately reduced by OA with protein S anticoagulant activi ty comparing well to factor IX clotting activity. These data suggest the possibility of identifying both quantitative and qualita tive deficiencies of protein C and protein S in patients on oral anticoagulant treatment.

Molecular Basis for A Thrombophilic Patient's Combined Deficiencies in Proteins C and S.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4198-4198
Author(s):  
Tyler W Smith ◽  
Isis S. R Carter ◽  
Cedric John Carter ◽  
Ross T.A MacGillivray
Keyword(s):  
Amino Acid ◽  
Dna Sequences ◽  
Promoter Region ◽  
Protein C ◽  
Conflicts Of Interest ◽  
Genetic Defect ◽  
Protein S ◽  
Catalytic Triad ◽  
Chromosome 2 ◽  
Amino Acid Residues

Abstract Abstract 4198 Background/objectives Proteins C and S (PC and PS) are vitamin K-dependent plasma proteins with anticoagulant properties. Protein S functions as a non-enzymatic cofactor for activated protein C (APC). APC proteolytically degrades coagulation factors Va and VIIIa, thereby diminishing the activities of the prothrombinase and tenase complexes, respectively. The human PC gene (PROC) is located on the long arm of chromosome 2 (2q13-q14) and contains 9 exons which code for 461 amino acid residues. The human PS (PROS1) gene resides on chromosome 3 (3p11.1-q11.2) and contains 15 exons coding for 636 amino acid residues. Hereditary PS and PC deficiencies are both autosomal dominant disorders in which patients have diminished functional levels of the respective protein (usually ∼50% relative to normal controls). Clinically, this results in increased propensity toward thromboembolic disease, also known as thrombophilia. In this study, we describe a unique thrombophilic patient who has combined deficiencies in both proteins C and S. The objective of the study was to elucidate the precise genetic defect(s) causing these deficiencies. Methods Following purification of the patient's DNA from peripheral blood leukocytes, PCR amplifications were performed using oligonucleotide primers flanking all exons of the PROS1 and PROC genes. In addition, the 400bp region upstream of the first exon of PROS1 (corresponding to the promoter region) was also amplified by PCR. The PCR products were purified and their DNA sequences determined in both forward and reverse directions using the dye-terminator method. The resultant nucleotide sequences were compared with the PROS1 and PROC reference sequences [web address]. Results The patient was found to be heterozygous for a novel missense PROC gene mutation in exon 8, which codes in part for the proteolytic domain of protein C. The resulting ValàGly substitution of residue 221 is in close proximity to the catalytic triad, which could abrogate its enzymatic activity. Although no mutations were present in any of the patient's PROS1 exons, there was a novel heterozygous CàG nucleotide substitution in the PROS1 promoter region. This substitution is present within an Sp1 transcription factor binding site that is highly conserved among mammals. Therefore, this mutation could significantly diminish expression of the otherwise normal PROS1 gene, leading to the observed decreased protein S level. Both mutations are unreported in the literature and are not listed in the PROC and PROS1 mutation databases. Conclusions We have successfully identified two novel genetic defects leading to deficiencies of the anticoagulant proteins C and S in a patient with thrombophilia. Further studies are underway to confirm the suggested biochemical effects of the mutation on protein C and protein S gene expression. Disclosures: No relevant conflicts of interest to declare.

Protein S Released From Stimulated Platelets Has Anticoagulant Activity Independent of Activated Protein C and Tissue Factor Pathway Inhibitor (TFPI).

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1137-1137
Author(s):  
Mary J. Heeb ◽  
Erning Duan
Keyword(s):  
Plasma Protein ◽  
Neutralizing Antibodies ◽  
Protein C ◽  
Thrombin Generation ◽  
Conflicts Of Interest ◽  
Anticoagulant Activity ◽  
Activated Protein C ◽  
Protein S ◽  
Platelet Protein ◽  
Presence And Absence

Abstract Abstract 1137 Background: Platelets contain in their alpha granules ∼2.5% of the protein S in blood. It has been suggested that this protein S supports the anticoagulant activity of exogenous activated protein C (APC), but it is not known whether protein S that is released from stimulated platelets can exert anticoagulant activity that is independent of APC and TFPI. We recently showed that at least some of the anticoagulant activity of plasma protein S is independent of APC and TFPI, although data suggested that plasma protein S may also have TFPI-dependent activity. Objective and methods: To determine if platelet protein S has anticoagulant activity that is independent of APC and TFPI, prothrombinase and extrinsic FXase reactions were initiated on the surface of fresh stimulated or unstimulated washed platelets in the presence and absence of blocking antibodies against APC, TFPI, and/or protein S, or in the presence and absence of purified plasma-derived protein S. Platelets were adjusted to a concentration of 0.7 to 2 × 10e8/ml, which contained 2.3–6.5 nM total platelet protein S. The last platelet wash contained negligible amounts of plasma protein S. Results: Neutralizing anti-protein S antibodies allowed up to 5.7-fold (mean: 2.1 ± 1.5 –fold, n=13) more thrombin generation on calcium ionophore-stimulated platelets following supplementation with 50–500 pM FXa and 600 nM prothrombin, and allowed up to 2.5-fold (mean: 1.7 ± 0.7 –fold, n=11) more thrombin generation on platelets that were not ionophore-stimulated but were gradually stimulated following FXa and prothrombin supplementation. Anti-protein S antibodies had no effect on thrombin generation on platelets that were treated with prostaglandin E1 (PGE1) to suppress platelet activation and then supplemented with procoagulants. This implies that platelet protein S is released from stimulated platelets and downregulates thrombin generation on platelets, and that neutralizing anti-protein S antibodies block this activity of protein S. Anti-protein S antibodies allowed up to 1.8-fold (mean 1.5 ± 0.2 –fold, n=8) more FXa generation on the surface of stimulated platelets supplemented with 5 pM TF, 100 pM FVIIa, and 160 nM FX, but anti-protein S antibodies had no effect on FXa generation on platelets treated with PGE1. Most of these experiments were performed in the presence of neutralizing antibodies against TFPI and APC, but thrombin and FXa generation on platelets under the varying conditions described were unaffected by the presence of these neutralizing antibodies. Purified plasma-derived zinc-containing protein S downregulated thrombin and FXa generation on platelets (IC50 = 6–18 nM PS) and in plasma >10-fold more potently than zinc-deficient protein S. We could not demonstrate a synergistic anticoagulant effect when TFPI was combined with zinc-deficient protein S in the presence of stimulated platelets and procoagulant proteins. Conclusion: Protein S that is released from stimulated platelets exerts anticoagulant activity that is independent of TFPI and APC. Disclosures: No relevant conflicts of interest to declare.

Protein S As a Potential Treatment for FIX-Derived Deep Vein Thrombosis

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2277-2277
Author(s):  
Vijaya Satish Sekhar Pilli ◽  
Willium Plautz ◽  
Rinku Majumder ◽  
Paolo Simioni
Keyword(s):  
Deep Vein Thrombosis ◽  
Thrombin Generation ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Protein S ◽  
Factor Ix ◽  
Wild Type ◽  
Vein Thrombosis ◽  
Deep Vein

Abstract Background: Every year, 0.1-0.2% of the USA population experiences deep vein thrombosis (DVT). Two causes of DVT are increased Factor IX (FIX) levels and hyperactivating mutations in FIX (FIX Padua variant- R338L and Malmo variant T148A). In principle, inhibition of activated FIX (FIXa) should alleviate DVT. Previous in vitro studies demonstrated that the anticoagulant Protein S (PS) inhibits the intrinsic pathway mediated by wild type FIXa, making PS an attractive candidate to treat DVT. Aims: To establish Protein S as a remedy for FIX-mediated DVT/Padua/Malmo Methods: Anisotropy, clotting assays, thrombin generation assays, co-localization, co-immunoprecipitation, and bleeding assays. Results: We further explored the physiological relevance of the PS-FIXa interaction and PS-mediated inhibition of FIXa by ex vivo (co-immunoprecipitation) and in vivo (co-localization) studies. Because PS can inhibit FIXa in vivo, we used competitive, direct anisotropy assays and co-immunoprecipitation assays to measure the efficiency PS and hyperactive FIXa (R338L) interaction. Interestingly, the results demonstrated that FIXa R338L has lost its affinity towards PS compared with wild type FIXa. The same finding was obtained by ex vivo thrombin generation assays and FXa generation assays supplemented with various concentrations of PS. Thus, to be inhibited, hyperactive FIX requires a greater amount of PS compared with wild type FIXa. We are further confirming this finding with mouse models. Conclusion: Addition of PS to plasma inhibits both wild type and R338L FIXa and extends clotting time. Previous studies showed that the addition of PS has no significant negative effects. Thus, we conclude that PS supplementation potentially constitutes a novel and effective treatment for FIX-mediated DVT. Disclosures No relevant conflicts of interest to declare.

scholarly journals A role for factor XIIa–mediated factor XI activation in thrombus formation in vivo

Blood ◽  
2010 ◽  
Vol 116 (19) ◽  
pp. 3981-3989 ◽  
Author(s):  
Qiufang Cheng ◽  
Erik I. Tucker ◽  
Meghann S. Pine ◽  
India Sisler ◽  
Anton Matafonov ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Thrombus Formation ◽  
Arterial Occlusion ◽  
Factor Ix ◽  
Bleeding Complications ◽  
Similar Degree ◽  
Factor Xii ◽  
Factor Xi ◽  
Deficient Mice

AbstractMice lacking factor XII (fXII) or factor XI (fXI) are resistant to experimentally–induced thrombosis, suggesting fXIIa activation of fXI contributes to thrombus formation in vivo. It is not clear whether this reaction has relevance for thrombosis in pri mates. In 2 carotid artery injury models (FeCl3 and Rose Bengal/laser), fXII-deficient mice are more resistant to thrombosis than fXI- or factor IX (fIX)–deficient mice, raising the possibility that fXII and fXI function in distinct pathways. Antibody 14E11 binds fXI from a variety of mammals and interferes with fXI activation by fXIIa in vitro. In mice, 14E11 prevented arterial occlusion induced by FeCl3 to a similar degree to total fXI deficiency. 14E11 also had a modest beneficial effect in a tissue factor–induced pulmonary embolism model, indicating fXI and fXII contribute to thrombus formation even when factor VIIa/tissue factor initiates thrombosis. In baboons, 14E11 reduced platelet-rich thrombus growth in collagen-coated grafts inserted into an arteriovenous shunt. These data support the hypothesis that fXIIa-mediated fXI activation contributes to thrombus formation in rodents and primates. Since fXII deficiency does not impair hemostasis, targeted inhibition of fXI activation by fXIIa may be a useful antithrombotic strategy associated with a low risk of bleeding complications.

Heritability of Inter-Related Clotting Factors.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2585-2585
Author(s):  
Carla Vossen ◽  
Peter Callas ◽  
Frits Rosendaal ◽  
Sandra Hasstedt ◽  
Bruce Scott ◽  
...  
Keyword(s):  
Protein C ◽  
Plasma Concentrations ◽  
Principal Component ◽  
Protein S ◽  
Coagulation Factors ◽  
Pleiotropic Effect ◽  
Factor Ix ◽  
Factor V ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract The identification of genes affecting plasma concentrations of biological traits remains difficult, as the loci affecting such traits (termed quantitative trait loci) tend to explain only a fraction of the phenotypic variation. Evidence on inter-relation (i.e. clustering) of coagulation factors in the literature (Van Hylckama Vlieg 2003) suggests the existence of quantitative trait loci, which influence plasma concentrations of several quantitative traits (i.e.have a pleiotropic effect) outside the genes coding for these factors. The aim of the present study was to identify clusters of pro- and anticoagulant factors within a large protein C deficient kindred using principal components analysis. In addition, we wanted to determine how much of the variance within these clusters could be attributed to the genetic variation within a single large pedigree. Levels of the following analytes were measured in family members: prothrombin, factor V, VII, VIII, IX, X, fibrinogen, von Willebrand factor, antithrombin, protein C and protein S. Subjects with the 3363C protein C mutation, a personal history of thrombosis or those using oral anticoagulants, and women pregnant at the time of the blood draw were excluded from the analyses. To identify clusters of haemostatic factors, the principal component method with orthogonal varimax rotation was performed using SPSS. We used a factor loading of &gt;0.40 as a marginal value to include coagulation factors in a cluster. Heritability, the proportion of the phenotypic variance attributed to polygenes, and common household effect, the proportion of the variance attributed to environmental factors shared within a household, were estimated for each principal component score with an eigenvalue (the variance attributable to a particular principal component) greater than or equal to 1 using the variance component method in SOLAR (Almasy & Blangero 1998). The distribution of each score was assumed to be multivariate normal with a variance-covariance matrix following the formula: covariance (one person to another person)=h2K + c2H + e2I, with K derived from the kinship matrix, H from the household matrix and I from the identity matrix. The additive genetic and household components of variance were estimated using maximum likelihood analysis. A total of 87 family members met the inclusion criteria. The principal components analysis identified 3 components which explained 60% of the variance: component 1 included all vitamin K dependent factors (prothrombin, factor VII, factor IX and factor X, protein C and protein S), component 2 consisted of factor V, factor IX, fibrinogen and antithrombin, which all can interact directly with thrombin, and component 3 consisted of factor VIII and its carrier protein von Willebrand factor. The heritability estimates for these 3 components were, respectively, 96% (p=0.002), 87% (p&lt;0.001) and 12% (p=0.33). These findings appear to provide evidence for the existence of genes that regulate the levels of distinct groups of proteins in the coagulation system, thus leading to clustering of levels suggestive of a pleiotropic effect.

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