Recurring myocardial infarction in a 35 year old woman.
(1/137)
A 35 year old woman presented with acute myocardial infarction without any of the usual risk factors: she had never smoked; she had normal blood pressure; she did not have diabetes; plasma concentrations of total cholesterol and high and low density lipoprotein cholesterol, fibrinogen, homocysteine, and Lp(a) lipoprotein were normal. She was not taking oral contraceptives or any other medication. Coronary angiography showed occlusion of the left anterior descending coronary artery but no evidence of arteriosclerosis. Medical history disclosed a previous leg vein thrombosis with pulmonary embolism. Coagulation analysis revealed protein C deficiency. The recognition of protein C deficiency as a risk factor for myocardial infarction is important as anticoagulation prevents further thrombotic events, whereas inhibitors of platelet aggregation are ineffective. (+info)
Thrombophilia as a multigenic disease.
(2/137)
BACKGROUND AND OBJECTIVE: Venous thrombosis is a common disease annually affecting 1 in 1000 individuals. The multifactorial nature of the disease is illustrated by the frequent identification of one or more predisposing genetic and/or environmental risk factors in thrombosis patients. Most of the genetic defects known today affect the function of the natural anticoagulant pathways and in particular the protein C system. This presentation focuses on the importance of the genetic factors in the pathogenesis of inherited thrombophilia with particular emphasis on those defects which affect the protein C system. INFORMATION SOURCES: Published results in articles covered by the Medline database have been integrated with our original studies in the field of thrombophilia. STATE OF THE ART AND PERSPECTIVES: The risk of venous thrombosis is increased when the hemostatic balance between pro- and anti-coagulant forces is shifted in favor of coagulation. When this is caused by an inherited defect, the resulting hypercoagulable state is a lifelong risk factor for thrombosis. Resistance to activated protein C (APC resistance) is the most common inherited hypercoagulable state found to be associated with venous thrombosis. It is caused by a single point mutation in the factor V (FV) gene, which predicts the substitution of Arg506 with a Gln. Arg506 is one of three APC-cleavage sites and the mutation results in the loss of this APC-cleavage site. The mutation is only found in Caucasians but the prevalence of the mutant FV allele (FV:Q506) varies between countries. It is found to be highly prevalent (up to 15%) in Scandinavian populations, in areas with high incidence of thrombosis. FV:Q506 is associated with a 5-10-fold increased risk of thrombosis and is found in 20-60% of Caucasian patients with thrombosis. The second most common inherited risk factor for thrombosis is a point mutation (G20210A) in the 3' untranslated region of the prothrombin gene. This mutation is present in approximately 2% of healthy individuals and in 6-7% of thrombosis patients, suggesting it to be a mild risk factor of thrombosis. Other less common genetic risk factors for thrombosis are the deficiencies of natural anticoagulant proteins such as antithrombin, protein C or protein S. Such defects are present in less than 1% of healthy individuals and together they account for 5-10% of genetic defects found in patients with venous thrombosis. Owing to the high prevalence of inherited APC resistance (FV:Q506) and of the G20210A mutation in the prothrombin gene, combinations of genetic defects are relatively common in the general population. As each genetic defect is an independent risk factor for thrombosis, individuals with multiple defects have a highly increased risk of thrombosis. As a consequence, multiple defects are often found in patients with thrombosis. (+info)
Risk of venous thromboembolism and clinical manifestations in carriers of antithrombin, protein C, protein S deficiency, or activated protein C resistance: a multicenter collaborative family study.
(3/137)
Deficiencies of antithrombin (AT), protein C (PC) or protein S (PS), and activated protein C resistance (APCR) are very well-established coagulation defects predisposing to venous thromboembolism (VTE). We performed a retrospective cohort family study to assess the risk for VTE in individuals with AT, PC, or PS deficiency, or APCR. Five hundred thirteen relatives from 9 Italian centers were selected from 233 families in which the proband had had at least 1 episode of VTE. We calculated the incidence of VTE in the whole cohort and in the subgroups after stratification by age, sex, and defect. The overall incidence of VTE (per 100 patient-years) in the group of relatives was 0.52. It was 1.07 for AT, 0.54 for PC, 0.50 for PS, 0.30 for APCR, and 0.67 in the group with a double defect. The incidence was associated with age, but not with sex. The mean age at onset was between 30 and 40 years for all the coagulation defects. Women had the peak of incidence in the age range of 21 to 40 years, earlier than men. The lifetime risk for VTE was 4.4 for AT versus APCR, 2.6 for AT versus PS, 2.2 for AT versus PC, 1.9 for PC versus APCR, and 1.6 for PS versus APCR. AT deficiency seems to have a higher risk for VTE than the other genetic defects. There is a relation between age and occurrence of thrombosis for both men and women. The latter had the peak of incidence earlier than the former. (+info)
A molecular model of a point mutation (Val297Met) in the serine protease domain of protein C.
(4/137)
A heterozygous GTG to ATG (Val297Met) mutation was detected in a patient with inherited protein C deficiency and deep vein thrombosis. Cosegregation of the mutation with protein C deficiency was observed through a family pedigree study. Molecular models of the serine protease domains of wild type and mutant protein C were constructed by standard comparative method. Val 297 was found to be located in the hydrophobic core of the protein. Although the substitution of Met for Val does not greatly alter the hydrophobicity of the protein, it introduces a bulkier side chain, which yields steric hindrance between this residue and adjacent residues, such as Met364, Tyr393, Ile321, Ile323, and Val378. It seems that the Met can not fit into the tight packing into which it is trapped, thereby probably inducing misfolding and/or greater instability of the protein. Such misfolding and/or instability thereby eventually disturbs the catalytic triad, in consistent with the observed type I deficiency state. (+info)
Haemostatic and metabolic abnormalities in women with unexplained recurrent abortion.
(5/137)
The objective of this study was to establish whether or not patients with unexplained recurrent abortion have an increased incidence of haemostatic or metabolic abnormalities. Fifty-two patients with a history of unexplained habitual abortion (two or more spontaneous abortions before 16 weeks' gestation) were tested for protein S, protein C and antithrombin (AT) III deficiency, activated protein C (aPC) resistance, hyperhomocysteinaemia and anticardiolipin antibodies (ACA). The control group consisted of 67 healthy women with a history of only uncomplicated pregnancies. Blood samples were taken for measuring protein S, protein C, AT III, ACA and activated protein C resistance and a methionine loading test was performed. Of the 46 patients tested for protein S deficiency, 8 (17.4%) were positive. Of the 43 patients tested, two (4.7%) were protein C deficient and none was AT III deficient. Of the 42 patients tested for ACA, eight (19.1%) had detectable antibodies. Of the 44 patients tested for aPC resistance, two (4.6%) were positive. Finally, 35 patients were tested for hyperhomocysteinaemia and six (17.1%) were positive. It was concluded that parous women with a history of unexplained recurrent abortion have an increased incidence of hyperhomocysteinaemia and a trend of increased incidence of ACA can be found. (+info)
Mesenteric infarction due to combined protein C deficiency and prothrombin 20210 defects.
(6/137)
The prothrombin gene mutation, 20210A, a guanine to adenine substitution at nucleotide position 20210, has recently been described as an additional risk factor for venous thromboembolic disease. We describe the case of a patient with combined heterozygous prothrombin 20210A mutation and type 1 protein C deficiency who presented with massive mesenteric venous infarction of his small bowel and survived following the use of protein C concentrate and extensive small bowel resection. (+info)
The incidence of venous thromboembolism in asymptomatic carriers of a deficiency of antithrombin, protein C, or protein S: a prospective cohort study.
(7/137)
Deficiencies of antithrombin, protein C, and protein S are associated with an increased risk of venous thromboembolism. The objective of this study was to prospectively assess the incidence of venous thromboembolism in nontreated asymptomatic subjects with such a deficiency. We conducted a prospective cohort study in asymptomatic family members of unselected patients who presented with a venous thromboembolic event and who were found to have a deficiency of antithrombin, protein C, or protein S. No anticoagulant prophylaxis was given to the study participants, except during risk periods for venous thromboembolism. All venous thromboembolic events were diagnosed by objective diagnostic tests. A total of 208 individuals with a mean age of 37 years (range, 15 to 79) were included in the study. A total of 611 patient observation years was obtained. Nine venous thromboembolic events occurred, resulting in an annual incidence of 1.5% (95% confidence interval [CI], 0.7 to 2.8) for the 3 deficiencies combined. Five of these events occurred spontaneously, resulting in an annual incidence of spontaneous venous thromboembolism of 0.8% (95% CI, 0.3 to 1.9). For antithrombin, protein C, and protein S deficiencies separately, this figure was 1.6%, 1.0%, and 0.4%, respectively. Thirty-four subjects experienced a total of 40 risk periods during which 4 venous thromboembolic events occurred (10% per risk period). We conclude that the use of continuous anticoagulant prophylaxis seems not warranted in asymptomatic individuals with a deficiency of antithrombin, protein C, or protein S. During risk periods for venous thromboembolism, adequate anticoagulant prophylaxis is necessary. (+info)
Deficiency of natural anticoagulant proteins C, S, and antithrombin in portal vein thrombosis: a secondary phenomenon?
(8/137)
BACKGROUND: Hereditary deficiencies of natural anticoagulant proteins are implicated in the pathogenesis of portal vein thrombosis (PVT). Secondary deficiencies of these proteins have also been reported in PVT, making interpretation of concentrations difficult. AIMS: To characterise the coagulation profiles in adult patients with PVT and to investigate the possible mechanisms of natural anticoagulant protein deficiency. PATIENTS: Twenty nine adult patients with portal hypertension caused by PVT, and normal biochemical liver function tests. METHODS: Routine coagulation profiles and concentrations of proteins C, S, and antithrombin were measured; where indicated, corresponding concentrations in parents were also measured. Synchronous peripheral and hepatic or splenic vein concentrations were compared in seven patients undergoing interventional procedures, as were peripheral concentrations before and after shunt surgery in three patients. RESULTS: Deficiencies of one or more of the natural anticoagulant proteins occurred in 18 patients (62%), with six patients having combined deficiency of all three proteins. There were strong correlations between prothrombin and partial thromboplastin time ratios and concentrations of natural anticoagulant proteins. Family studies in nine cases of anticoagulant protein deficiency revealed possible hereditary deficiency in only three cases, and significantly lower concentrations of anticoagulant proteins in all PVT cases compared with parents. Levels of anticoagulant proteins tended to be lower in hepatic veins but higher in splenic veins compared with peripheral vein concentrations. Peripheral concentrations decreased after shunt surgery. CONCLUSIONS: Deficiency of natural anticoagulant proteins is common in PVT and is probably a secondary phenomenon in most cases, occurring as part of a global disturbance of coagulation variables. The mechanism for this remains unclear but may result from a combination of reduced hepatic blood flow and portosystemic shunting itself. (+info)