Resistance to activated protein C (APC) is the most prevalent inherited cause of venous thrombosis. The APC resistance phenotype is associated with a single point mutation in the factor V gene, changing Arg' in the APC cleavage site to a Gln. We have investigated 50 Swedish families with inherited APC resistance for this mutation and found it to be present in 47 of them. Perfect cosegregation between a low APC ratio and the presence of mutation was seen in 40 families. In seven families, the co-segregation was not perfect as 12 out of 57 APC-resistant family members were found to lack the mutation. Moreover, in three families with APC resistance, the factor V gene mutation was not found, suggesting another still unidentified cause of inherited APC resistance. Of 308 investigated families members, 146 were normal, 144 heterozygotes, and 18 homozygotes for the factor V gene mutation and there were significant differences in thrombosis-free survival curves between these groups. By age 33 yr, 8% of normals, 20% of heterozygotes, and 40% of homozygotes had had manifestation of venous thrombosis. (J. Clin. Invest. 1994. 94:2521-2524.) Key words: blood coagulation * thrombophilia -protein C * protein S * factor V recently discovered in a single family (2) and is already recognized as a major cause of venous thrombosis (3-6). Intact factor V was found to correct APC resistance (7) which together with close linkage between APC resistance and the factor V gene (8, 9), suggested the molecular defect to be located in the factor V gene. A single point mutation (G to A at position 1691) has been found in many APC-resistant individuals (8)(9)(10)(11). This mutation predicts replacement of Arg5 in the APC cleavage site of factor Va with a Gln, which results in APCresistant factor Va (8,12). The prevalence in the European population of APC resistance is between 3 and 7% (3, 5).Recently, our laboratory found intact factor V to function in synergy with protein S as cofactor to APC in a purified factor VIIIa degradation system ( 13 ). This suggests the possibility of thrombophilia being the result of other factor V gene mutations causing defects in the anticoagulant function of factor V, but as yet there are no such cases described.We have previously described a large number of families with inherited APC resistance (2-3, 9). To elucidate whether the Arg5 to Gln mutation was present in all of them, or if other genetic defects may also cause or contribute to the APC resistance, 308 individuals from 50 families with inherited resistance to activated protein C were investigated. The APC resistance was found to be associated with the same factor V gene mutation in 47 of the 50 families.

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Key Points Question To what extent are established cardiovascular risk factors associated with risk of venous thromboembolism (VTE)? Findings In this analysis of individual participant data from the Emerging Risk Factors Collaboration and the UK Biobank including 1.1 million participants, among a panel of several established cardiovascular risk factors, older age, smoking, and greater adiposity were consistently associated with higher VTE risk. Meaning There is overlap in at least some of the major population determinants of important venous and arterial thrombotic diseases.

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SummaryA dimorphism in the 3’-untranslated region of the prothrombin gene (G to A transition at position 20210) has recently been reported to be associated with increases in plasma prothrombin levels and in the risk of venous thrombosis (1). We have examined the prothrombin dimorphism among 99 unselected outpatients with phlebography verified deep venous thrombosis, and in 282 healthy controls. The prevalence of the 20210 A allele was 7.1% (7/99) in the patient group, and 1.8% (5/282) in the healthy control group (p = 0.0095). The relative risk of venous thrombosis was calculated to be 4.2 (95% Cl, 1.3 to 13.6), and was still significant when adjustment was made for age, sex and the factor V:R506Q mutation causing APC resistance [odds ratio 3.8 (95% Cl, 1.1 13.2)]. As previously reported, 28% of the patients were carriers of the factor V:R506Q mutation. Thus, 34% (one patient carried both traits) of unselected patients with deep venous thrombosis were carriers of an inherited prothrombotic disorder. To sum up, our results confirm the 20210 A allele of the prothrombin gene to be an important risk factor for venous thrombosis.

ObjectiveTransitions in the spectrum of valvular heart diseases (VHDs) in developed countries over the 20th century have been reported from clinical case series, but large, contemporary population-based studies are lacking.MethodsWe used nationwide registers to identify all patients with a first diagnosis of VHD at Swedish hospitals between 2003 and 2010. Age-stratified and sex-stratified incidence of each VHD and adjusted comorbidity profiles were assessed.ResultsIn the Swedish population (n=10 164 211), the incidence of VHD was 63.9 per 100 000 person-years, with aortic stenosis (AS; 47.2%), mitral regurgitation (MR; 24.2%) and aortic regurgitation (AR; 18.0%) contributing most of the VHD diagnoses. The majority of VHDs were diagnosed in the elderly (68.9% in subjects aged ≥65 years), but pulmonary valve disease incidence peaked in newborns. Incidences of AR, AS and MR were higher in men who were also more frequently diagnosed at an earlier age. Mitral stenosis (MS) incidence was higher in women. Rheumatic fever was rare. Half of AS cases had concomitant atherosclerotic vascular disease (48.4%), whereas concomitant heart failure and atrial fibrillation were common in mitral valve disease and tricuspid regurgitation. Other common comorbidities were thoracic aortic aneurysms in AR (10.3%), autoimmune disorders in MS (24.5%) and abdominal hernias or prolapse in MR (10.7%) and TR (10.3%).ConclusionsClinically diagnosed VHD was primarily a disease of the elderly. Rheumatic fever was rare in Sweden, but specific VHDs showed a range of different comorbidity profiles . Pronounced sex-specific patterns were observed for AR and MS, for which the mechanisms remain incompletely understood.

Inherited resistance to activated protein C (APC), which is caused by a single point mutation in the gene for factor V, is a common risk factor for thrombosis. In this study, the prevalence of APC resistance in 18 unrelated thrombosis-prone families with inherited protein S deficiency was investigated to determine its role as additional genetic risk factor for thrombosis. In addition, a detailed evaluation of the clinical manifestations in these families was performed. Venous thrombotic events had occurred in 47% of the protein S-deficient patients (64/136) and in 7% of relatives without protein S deficiency (14/191). As estimated from Kaplan-Meier analysis, 50% of protein S-deficient family members and 12% of those without protein S deficiency had had manifestation of venous thromboembolism at the age of 45 years. The age at the first thrombotic event ranged from 10 to 81 years (mean, 32.5 years) and a large intrafamilial and interfamilial variability in expression of thrombotic symptoms was seen. The factor V gene mutation related to APC resistance was present in 6 (38%) of 16 probands available for testing; in total, the mutation was found in 7 (39%) of the 18 families. In family members with combined defects, 72% (13/18) had had thrombosis as compared with 19% (4/21) of those with only protein S deficiency and 19% (4/21) of those with only the factor V mutation. In conclusion, APC resistance was found to be highly prevalent in thrombosis-prone families with protein S deficiency and was an additional genetic risk factor for thrombosis in these families. The results suggest thrombosis-prone families with protein S deficiency often to be affected by yet another genetic defect.