Case report: persistently seronegative neuroborreliosis in an immunocompromised patient.

BACKGROUND: Infection with Borrelia burgdorferi sensu lato complex (B. b. sl) spirochetes can cause Lyme borreliosis, manifesting as localized infection (e.g. erythema migrans) or disseminated disease (e.g. Lyme neuroborreliosis). Generally, patients with disseminated Lyme borreliosis will produce an antibody response several weeks post-infection. So far, no case of neuroborreliosis has been described with persistently negative serology one month after infection. CASE PRESENTATION: We present a patient with a history of Mantle cell lymphoma and treatment with R-CHOP (rituximab, doxorubicine, vincristine, cyclofosfamide, prednisone), with a meningo-encephalitis, who was treated for a suspected lymphoma relapse. However, no malignant cells or other signs of malignancy were found, and microbial tests did not reveal any clues, including Borrelia serology. He did not recall being bitten by ticks, and a Borrelia PCR on CSF was negative. After spontaneous improvement of symptoms, he was discharged without definite diagnosis. Several weeks later, he was readmitted with a relapse of symptoms of meningo-encephalitis. This time however, a Borrelia PCR on CSF was positive, confirmed by two independent laboratories, and the patient received ceftriaxone upon which he partially recovered. Interestingly, during the diagnostic process of this exceptionally difficult case, a variety of different serological assays for Borrelia antibodies remained negative. Only P41 (flagellin) IgG was detected by blot and the Liaison IgG became equivocal 2 months after initial testing. CONCLUSIONS: To the best of our knowledge this is the first case of neuroborreliosis that is seronegative on repeated sera and multiple test modalities. This unique case demonstrates the difficulty to diagnose neuroborreliosis in severely immunocompromised patients. In this case, a delay in diagnosis was caused by broad differential diagnosis, an absent known history of tick bites, negative serology and the low sensitivity of PCR on CSF. Therefore, awareness of the diagnostic limitations to detect Borrelia infection in this specific patient category is warranted.

Impact of the COVID-19 outbreak on acute stroke care.

BACKGROUND AND PURPOSE: There are concerns that the coronavirus disease 2019 (COVID-19) outbreak negatively affects the quality of care for acute cardiovascular conditions. We assessed the impact of the COVID-19 outbreak on trends in hospital admissions and workflow parameters of acute stroke care in Amsterdam, The Netherlands. METHODS: We used data from the three hospitals that provide acute stroke care for the Amsterdam region. We compared two 7-week periods: one during the peak of the COVID-19 outbreak (March 16th-May 3th 2020) and one prior to the outbreak (October 21st-December 8th 2019). We included consecutive patients who presented to the emergency departments with a suspected stroke and assessed the change in number of patients as an incidence-rate ratio (IRR) using a Poisson regression analysis. Other outcomes were the IRR for stroke subtypes, change in use of reperfusion therapy, treatment times, and in-hospital complications. RESULTS: During the COVID-19 period, 309 patients presented with a suspected stroke compared to 407 patients in the pre-COVID-19 period (IRR 0.76 95%CI 0.65-0.88). The proportion of men was higher during the COVID-19 period (59% vs. 47%, p < 0.001). There was no change in the proportion of stroke patients treated with intravenous thrombolysis (28% vs. 30%, p = 0.58) or endovascular thrombectomy (11% vs 12%, p = 0.82) or associated treatment times. Seven patients (all ischemic strokes) were diagnosed with COVID-19. CONCLUSION: We observed a 24% decrease in suspected stroke presentations during the COVID-19 outbreak, but no evidence for a decrease in quality of acute stroke care.

Presentation outside office hours does not negatively influence treatment times for reperfusion therapy for acute ischemic stroke.

BACKGROUND: Treatment outside office hours has been associated with increased workflow times for intravenous thrombolysis (IVT) in acute ischemic stroke (AIS). Limited data suggest that this "off-hours effect" also exists for endovascular treatment (EVT). We investigated this phenomenon in a well-organized acute stroke care region in the Netherlands. METHODS: Retrospective, observational cohort study of consecutive patients with AIS who received reperfusion therapy in the Greater Amsterdam Area, consisting of 14 primary stroke centers and 1 comprehensive stroke center (IVT: 2009-2015, EVT: 2014-2017). Office hours were defined as presentation during weekdays between 8 AM and 5 PM, excluding National Festive days. Primary outcome was door-to-treatment time (door-to-needle [DNT] for IVT, door-to-groin [DGT] for EVT). For DGT, we used the door time of the first hospital. Other outcomes were in-hospital mortality, modified Rankin Scale (mRS) score at 90 days and symptomatic intracranial hemorrhage (sICH). We performed multivariable linear and logistic regression analyses and used multiple imputation to account for missing values. RESULTS: In total, 59% (2450/4161) and 61% (239/395) of patients treated with IVT and EVT, respectively, presented outside office hours. Median DNT was minimally longer outside office hours (32 vs. 30 min, p = 0.024, adjusted difference 2.5 min, 95% CI 0.7-4.2). Presentation outside office hours was not associated with a longer DGT (median 130 min for both groups, adjusted difference 7.0 min, 95% CI - 4.2 to 18.1). Clinical outcome and sICH rate also did not differ. CONCLUSION: Presentation outside office hours did not lead to clinically relevant treatment delays for reperfusion therapy in patients with AIS.

Gross deletions/duplications in PROS1 are relatively common in point mutation-negative hereditary protein S deficiency.

Hereditary protein S (PS) deficiency is an autosomal disorder caused by mutations in the PS gene (PROS1). Conventional PCR-based mutation detection identifies PROS1 point mutations in approximately 50% of the cases. To verify if gross copy number variations (CNVs) are often present in point mutation-negative hereditary PS deficiency we used multiplex ligation-dependent probe amplification (MLPA) as a detection tool in samples from individuals with a high probability of having true PS deficiency. To this end, DNA samples from nine PS deficient probands with family members (seven type I and two type III) and nine isolated probands (three type I and six type III), in whom PROS1 mutations were not found by DNA sequencing, were evaluated. An independent quantitative PCR (qPCR) was performed to confirm the findings of the MLPA assay. Family members were also tested when DNA was available. Gross abnormalities of PROS1 were found in six out of eighteen probands. In three probands complete deletion of the gene was detected. Two probands had a partial deletion involving different parts of the gene (one from exon 4 through 9 and another from exon 9 through 11). One family showed a duplication of part of PROS1. qPCR analysis was in accordance with these results. In conclusion, this study substantiates that gross gene abnormalities in PROS1 are relatively common in hereditary PS deficient patients and that MLPA is a useful tool for direct screening of CNVs in PROS1 point mutation-negative individuals.

Deep frontal and periventricular age related white matter changes but not basal ganglia and infratentorial hyperintensities are associated with falls: cross sectional results from the LADIS study.

BACKGROUND: Global age related white matter changes (ARWMC) are associated with progressive gait disturbances and falls, hypothesised to result from interruptions of cortico-subcortical circuits controlling balance, posture and locomotion. METHODS: The location of ARWMC in a large cohort of elderly non-disabled individuals with reported falls was analysed, using the cross sectional data of the Leukoaraiosis and Disability (LADIS) study. Detailed anatomical distributions of ARWMC assessed by MRI studies were analysed with respect to falls and balance performance. RESULTS: The severity of global ARWMC was significantly associated with a history of falls in the year prior to study inclusion (22.2% in the mild, 31.6% in the moderate and 37.3% in the severe ARWMC group according to the Fazekas scale; p = 0.002). Analysing the anatomical distribution of ARWMC, using the semiquantitative Scheltens scale, in multivariate analysis, periventricular (p = 0.006) and frontal deep (p = 0.033) ARWMC were independently associated with falls. Furthermore, logistic regression identified frontal deep (p = 0.003) ARWMC, but not basal ganglia and infratentorial hyperintensities, as significantly associated with balance disturbances. CONCLUSION: The association of frontal and periventricular ARWMC with falls supports the hypothesis that interruption of frontal subcortical motor circuits lead to balance disturbances and hence to an increased risk for falls in ARWMC.

Cost-effectiveness of post-diagnosis treatment in dementia coordinated by Multidisciplinary Memory Clinics in comparison to treatment coordinated by general practitioners: an example of a pragmatic trial.

BACKGROUND: With the rising number of dementia patients with associated costs and the recognition that there is room for improvement in the provision of dementia care, the question arises on how to efficiently provide high quality dementia care. OBJECTIVE: To describe the design of a study to determine multidisciplinary memory clinics' (MMC) effectiveness and cost-effectiveness in post-diagnosis treatment and care-coordination of dementia patients and their caregivers compared to the post-diagnosis treatment and care-coordination by general practitioners (GP). Next, this article provides the theoretical background of pragmatic trials, often needed in complex interventions, with the AD- Euro study as an example of such a pragmatic approach in a clinical trial. METHOD: The study is a pragmatic multicentre, randomised clinical trial with an economic evaluation alongside, which aims to recruit 220 independently living patients with a new dementia diagnosis and their informal caregivers. After baseline measurements, patient and caregiver are allocated to the treatment arm MMC or GP and are visited for follow up measurements at 6 and 12 months. Primary outcome measures are Health Related Quality of Life of the patient as rated by the caregiver using the Quality of Life in Alzheimer's Disease instrument (Qol-AD) and self-perceived caregiving burden of the informal caregiver measured using the Sense of Competence Questionnaire (SCQ). To establish cost-effectiveness a cost-utility analysis using utilities generated by the EuroQol instrument (EQ-5D) will be conducted from a societal perspective. Analyses will be done in an intention-to-treat fashion. RESULTS: The inclusion period started in January 2008 and will commence until at least December 2008. After finalising follow up the results of the study are expected to be available halfway through 2010. DISCUSSION: The study will provide an answer to whether follow-up of dementia patients can best be done in specialised outpatient memory clinics or in primary care settings with regard to quality and costs. It will enable decision making on how to provide good and efficient health care services in dementia. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT00554047.

Self-perceived memory impairment and cognitive performance in an elderly independent population with age-related white matter changes.

OBJECTIVES: To determine whether self-perceived memory impairment is associated with the severity of white matter changes (WMC) and is related to cognitive impairment. METHODS: Data were drawn from the multinational Leukoaraiosis and Disability Study (LADIS), which investigates the impact of WMC on global functioning. WMC severity was rated using the Fazekas scale. Medial temporal lobe atrophy (MTA) was scored visually and mean values were calculated. The neuropsychological battery consisted of the Mini-Mental State Examination, a modified version of the VADAS-Cog, Trail making and Stroop tests. A question about self-perceived memory impairment was used as a measure for presence of memory complaints. Cognitive performance was analysed test-by-test and in three main domains: memory, executive functions and speed/motor control. The Geriatric Depression Scale (GDS) was used as a measure of depressive symptoms. RESULTS: Six hundred and thirty-eight subjects were included in this study. No association was found between memory complaints and the severity of WMC. Subjects with memory complaints (n = 399) had a higher GDS score [t((637)) = -7.15; p<0.02] and performed worse on almost all cognitive tests and on the three cognitive domains. Multiple linear regression showed that the worse performance on the memory domain was associated with memory complaints independently of depressive symptoms, WMC severity and MTA (R(2) = 0.183; F = 17.09, beta = -0.126; p<0.05). CONCLUSION: In a sample of non-disabled elderly subjects with WMC, self-perceived memory impairment is significantly associated with objective memory impairment independently of the WMC severity, depressive symptoms and MTA.

[Blood pressure control in patients with a symptomatic carotid artery stenosis]. / Bloeddrukregulatie bij patiënten met een symptomatische carotisstenose.

Carotid artery stenosis is an important cause of transient ischaemic attacks (TIAs) and ischaemic strokes, and is associated with a particularly high risk of recurrent stroke both in the acute phase and the long-term. Early secondary preventive measures would therefore seem warranted. Carotid endarterectomy (CEA) is an effectively therapy in patients with a severe symptomatic stenosis. Hypertension is an important risk factor for recurrent stroke both in the acute phase and the long-term. Moreover, hypertension is an important risk factor for complications of CEA. In patients on the waiting list for CEA, following a TIA or a non-disabling ischaemic stroke, it would seem worthwhile to attempt to start antihypertensive treatment after approximately 24 h, and to at least strive after a preoperative systolic blood pressure of < 180 mmHg and a diastolic blood pressure of < 90 mmHg. In patients who cannot undergo surgery in the desirable short run, hypotensive treatment must be considered in the context of secondary prevention. The blood pressure target level depends on the presence or absence of a severe unilateral or bilateral stenosis (> 70% lumen diameter). In postoperative hypertension one must strive after a blood pressure < 140/90 mmHg, thereby avoiding an excessively rapid hypotensive response (> 25% daily). Patients with a TIA or an ischaemic stroke and a carotid artery stenosis must also be treated with antiplatelet agents and a statin, while other vascular risk factors must be controlled.

[Carotid calcification on a panoramic radiograph: what to do?]. / Een opaciteit in de hals op het orthopantomogram: wat te doen?

A 71-year-old man is discussed in whom the oral and maxillofacial surgeon observed, by chance, a radiopacity on the panoramic radiograph that was highly suggestive of a calcification at the bifurcation of the internal and external carotid artery. While, on the basis of international literature, various treatments are advanced with respect to the importance of vascular investigation and possible surgical removal of significant calcification, at present the view in The Netherlands is that the family doctor has the responsibility to assess whether such patient should be referred for further evaluation by the neurologist or vascular surgeon. The same applies to the possible indication for prescription of antitrombotics.

Discrepancy between the initial assessment of injury severity and post hoc determination of injury severity in patients with apparently mild traumatic brain injury: a retrospective multicenter cohort analysis.

PURPOSE: Traumatic brain injury (TBI) is a major cause of trauma-related visits to emergency departments (ED). Determination of monitoring requirements of patients with apparently mild TBI is challenging. Patients may turn out to be more severely injured than initially assumed, and failure to identify these patients constitutes a serious threat to patient safety. We, therefore, aimed to identify clinical risk factors for more severe injuries in patients with apparently mild TBI. METHODS: In a retrospective cohort analysis performed at two level I trauma centers, 808 patients aged ≥ 16 presenting to the ED with head trauma and a Glasgow Coma Scale (GCS) score 13-15 who received a head CT scan were studied. Discrepancies between the initial TBI severity as determined by GCS and severity as determined post hoc by the Head Abbreviated Injury Score were assessed. Multiple logistic regression was used to identify risk factors of such discrepancies. RESULTS: 104 (12.9%) patients were more severely injured than initially classified. A GCS < 15 at presentation (GCS 13: OR 6.2, [95% CI 3.8-9.9]; GCS 14: OR 2.7, [2.0-3.7]), an SpO2 < 90% (OR 5.4, [1.2-23.4]), loss of consciousness (OR 2.3, [1.5-3.5]), absence of equal and reactive pupils (OR 2.1, [1.6-2.7]), transport by ambulance (OR 2.0, [1.7-2.4]), and use of anticoagulant drugs (OR 1.2, [1.1-1.3]) were independent risk factors of more severe injury. CONCLUSIONS: Six risk factors of more severe injury in patients presenting with apparently mild TBI were identified. Patients with any of these factors should be thoroughly monitored for signs of neurologic deterioration.

Haemorrhagic stroke related to the use of 4-fluoroamphetamine.

INTRODUCTION: The use of the new psychoactive substance 4-fluoroamphetamine (4-FA) and the number of 4-FA-related intoxications substantially increased in The Netherlands in recent years. We describe two patients with severe 4-FA-related complications and the characteristics of a large sample of 4-FA-intoxicated patients. METHODS: Information on patients with 4-FA-related intoxications between January 2009 and June 2017 was available from the Monitor Drug-related Incidents. Detailed clinical information was obtained of two patients with haemorrhagic stroke after toxicologically confirmed 4-FA use. RESULTS: We report on two patients who presented with headache and mild hypertension after 4-FA use. Patient A developed one-sided weakness and decreased consciousness after a few hours. A computed tomography scan showed a left-sided intracerebral haemorrhage. Because of life-threatening cerebral herniation, haematoma evacuation was performed. Postoperatively, she suffered from a right-sided hemiparalysis and severe aphasia, requiring clinical rehabilitation. Patient B had a subarachnoid haemorrhage without neurological deficits. In total, 939 4-FA-intoxicated patients were registered. These patients used 4-FA alone (44%) or in combination with alcohol (13%) and/or other drugs (43%). DISCUSSION: Patients using 4-FA are at risk for life-threatening health problems, including intracranial haemorrhage. Additional brain imaging should be considered in 4-FA-intoxicated patients, not only in the presence of neurological deficits, but also in the case of severe headache.

Polymorphism 10034C>T is located in a region regulating polyadenylation of FGG transcripts and influences the fibrinogen gamma'/gammaA mRNA ratio.

BACKGROUND: Fibrinogen gamma haplotype 2 (FGG-H2) is associated with reduced fibrinogen gamma' levels and fibrinogen gamma'/total fibrinogen ratios and with an increased deep-venous thrombosis (DVT) risk. Two FGG-H2 tagging single nucleotide polymorphisms (SNPs), 9615C>T and 10034C>T, are located in the region of alternative FGG pre-mRNA processing. 10034C>T is located in a GT-rich downstream sequence element (DSE) that comprises a putative cleavage stimulation factor (CstF) binding site. OBJECTIVES: To investigate the functionality of SNPs 9615C>T and 10034C>T, and the importance of the DSE containing 10034C>T. METHODS: Different minigene constructs containing FGG exon 9, intron 9, exon 10 and the 3' region were transiently transfected into HepG2 cells and quantitative real-time polymerase chain reaction was used to measure relative polyadenylation (pA) signal usage (pA1/pA2 ratio). RESULTS: Compared with the reference construct CC (9615C-10034C; FGG-H1; pA1/pA2 ratio set at 100%), the pA1/pA2 ratio of construct TT (9615T-10034T; FGG-H2) was 1.4-fold decreased (71.5%, P = 0.015). The pA1/pA2 ratio of construct CT (9615C-10034T) was almost 1.2-fold decreased (85.3%, P = 0.001), whereas the pA1/pA2 ratio of construct TC (9615T-10034C) did not differ significantly from the reference construct (101.6%, P = 0.890). Functionality of the putative CstF binding site was confirmed using constructs in which this site was deleted or its sequence altered by point mutations. CONCLUSIONS: SNP 10034C>T is located in a GT-rich DSE involved in regulating the usage of the pA2 signal of FGG, which may represent a CstF binding site. We propose that the 10034C>T change is the functional variation in FGG-H2 that is responsible for the reduction in the fibrinogen gamma'/total fibrinogen ratio and the increased DVT risk.

Determinants of the APTT- and ETP-based APC sensitivity tests.

BACKGROUND: A reduced sensitivity for activated protein C (APC) is associated with an increased risk of venous thrombosis even in the absence of the factor (F)V Leiden mutation. This risk has been demonstrated with two APC sensitivity tests, which quantify the effects of APC on the activated partial thromboplastin time (APTT) and the endogenous thrombin potential (ETP), respectively. OBJECTIVES: We examined determinants of both APC sensitivity tests in the control group of the Leiden Thrombophilia Study (LETS). METHODS: Multiple linear regression analysis was performed with normalized APC-SR(APTT) or APC-SR(ETP) as dependent variable and putative determinants [levels of FII, FV, FVII, FVIII, FIX, FX, FXI, FXII, FXIII A subunit, FXIII B subunit, protein S total, protein S free, protein C, tissue factor pathway inhibitor (TFPI) total, TFPI free, antithrombin and fibrinogen] as independent variables. RESULTS AND CONCLUSIONS: The major determinant of the APTT-based test was FVIII level, followed by FII level. The ETP-based test was influenced most by free protein S and free TFPI levels. In both tests FXa formation plays a major role, as the effect of FVIII and TFPI on the tests seems to be executed via FXa. The ETP-based test was also strongly influenced by oral contraceptive use, even when we adjusted for all the clotting factors listed above. This means that the effect of oral contraceptives on the ETP-based test is not fully explained by the changes of coagulation factor levels investigated in this study, and that the molecular basis of acquired APC resistance during use of oral contraceptives remains to be established.

Haplotypes of the EPCR gene, plasma sEPCR levels and the risk of deep venous thrombosis.

BACKGROUND: Binding of protein C (PC) to the endothelial cell PC receptor (EPCR) stimulates PC activation by increasing the affinity of PC for the thrombin-thrombomodulin complex. A soluble form of this receptor (sEPCR) circulates in plasma and inhibits both PC activation and APC anticoagulant activity. OBJECTIVES: The aim of this study was to investigate whether variations in the EPCR gene or plasma sEPCR levels are risk factors for deep venous thrombosis (DVT). PATIENTS/METHODS: In a large case-control study, the Leiden Thrombophilia Study (LETS), sEPCR levels were measured by ELISA. All subjects were genotyped for three haplotype-tagging SNPs, enabling us to detect all four common haplotypes of the EPCR gene. RESULTS: The distribution of sEPCR levels in the control population was trimodal and was genetically controlled by haplotype 3 (H3). This haplotype explained 86.5% of the variation in sEPCR levels. Carriers of two H3 alleles had higher sEPCR levels (439 ng mL(-1)) than carriers of one H3 allele (258 ng mL(-1)), which had higher levels than non-H3 carriers (94 ng mL(-1)). Haplotype 4 was associated with a slightly increased risk (OR = 1.4, 95%CI:1.0-2.2). The risk of subjects with sEPCR levels in the top quartile (>/= 137 ng mL(-1)) was increased compared to that of subjects in the first quartile (< 81 ng mL(-1)), but since there was no dose-response effect, it is most likely that low sEPCR levels reduce the risk of DVT. CONCLUSIONS: Our data do not suggest a strong association between EPCR haplotypes and thrombosis risk, but low sEPCR levels appear to reduce the risk of DVT.

Linkage analysis of factor VIII and von Willebrand factor loci as quantitative trait loci.

Elevated factor (F)VIII levels contribute to venous thrombotic risk. FVIII levels are determined to a large extent by levels of von Willebrand factor (VWF), its carrier protein which protects FVIII against proteolysis. VWF levels are largely dependent on ABO blood group. Subjects with blood group non-O have higher VWF and FVIII levels than individuals with blood group O. Apart from ABO blood group no genetic determinants of high FVIII levels have been identified, whereas clustering of FVIII levels has been reported within families even after adjustment for ABO blood group and VWF levels. We investigated the FVIII and VWF loci as possible quantitative trait loci (QTL) influencing FVIII and VWF levels. Two sequence repeats in the FVIII gene and three repeats in the VWF gene were typed in 52 FV Leiden families. Multipoint sib-pair linkage analysis was performed with the MAPMAKER/SIBS program. FVIII levels adjusted for VWF levels and age, and VWF levels adjusted for ABO blood group and age, were used for this linkage analysis. No linkage of FVIII levels to the FVIII locus was found, whereas we found evidence that the VWF locus contains a QTL for VWF levels [maximum likelihood no dominance variance lod score = 0.70 (P = 0.04) and non-parametric Z-score = 1.92 (P = 0.03)]. About 20% of the total variation in VWF levels may be attributed to this VWF locus.

Determinants of rise in blood pressure in normotensive children.

Thirty-nine initially normotensive children (25 girls) with a large increase in systolic blood pressure (SBP) over a period of 7 years were compared with 78 children with a small increase, matched for age and gender. They were selected from a random sample of 596 Dutch children who were examined at an initial examination and 4 weeks later, and at yearly intervals thereafter. Body weight, height and Quetelet index at baseline were similar in children with a large rise in SBP and those with a small rise. Children with a large increase had a larger weight gain during follow-up than those with a small rise. Parental blood pressure (BP) and parental history of diabetes mellitus and cardiovascular diseases did not differ between the study groups. Cardiovascular reactivity as assessed by a cold-pressor test at baseline did not differ between the study groups, nor did urinary sodium excretion during follow-up. Total tobacco consumption was larger in those with a small increase. Children with a large rise in SBP experienced a larger fall in SBP from the initial to the 4-week examination. The individual variability of BP over the whole observation period did not differ between the study groups. These observations suggest that a fall in BP after a short follow-up period may be indicative of high BP in the years to come.

Factor X levels, polymorphisms in the promoter region of factor X, and the risk of venous thrombosis.

Elevated levels of procoagulant proteins factor II, factor VIII, factor IX, factor XI and fibrinogen are associated with an increased risk of venous thrombosis. In a population-based case-control study on venous thrombosis (Leiden Thrombophilia Study, LETS) we investigated whether elevated coagulation factor X (FX) levels are a risk factor for venous thrombosis and whether FX levels are determined by polymorphisms in the promoter region of the FX gene. We found that subjects with high FX levels (above the 90th percentile, > or = 126 U/dl) had a 1.6-fold increased risk of venous thrombosis. The highest risk (OR = 4.3, 95% confidence interval: 1.5-12) was found in the subgroup of premenopausal women who are not using oral contraceptives. However, these estimated risks disappeared after adjustment for other vitamin K-dependent coagulation factors II, VII and IX. To study the influence of genotypic variation on plasma FX levels we assessed four polymorphisms in the promoter region of the FX gene: a TTGTGA insertion between position -343A and -342G, a C/T polymorphism at position -222, a C/A polymorphism at position -220 and a C/T polymorphism at position -40. No relationship between these investigated genotypes and FX levels was observed. We conclude that high FX levels predict risk of thrombosis, but are not a risk factor for venous thrombosis when the levels of other vitamin K-dependent proteins are taken into account.

The HR2 haplotype of factor V is not associated with the risk of myocardial infarction.

The HR2 haplotype of the factor V gene, which contains the histidine to arginine substitution at position 1299, has been reported to be associated with reduced factor V levels. Because high factor V levels have been found to be associated with an increased risk of myocardial infarction, we examined how the presence of the R2 allele affected the risk of myocardial infarction in the case-control "Study of Myocardial Infarctions Leiden". Among 560 men with a first myocardial infarction before the age of 70 years, 9.5% were heterozygous carriers of the R2 allele. The control group consisted of 646 men, in which 9.9% were heterozygous and 0.2% homozygous carriers of the R2 allele. The risk of myocardial infarction in the presence of the R2 allele was not increased (odds ratio, 0.9; 95% confidence interval 0.6 to 1.4). Exclusion of factor V Leiden carriers did not change this result. The risk was 4.4-fold increased for smokers who carried the R2 allele compared to non-smoking noncarriers. No synergy was found between metabolic risk factors and the presence of the R2 allele. We conclude that the risk of myocardial infarction for men in the presence of the R2 allele of the His1299Arg polymorphism is neither increased nor decreased.

The HR2 haplotype of factor V: effects on factor V levels, normalized activated protein C sensitivity ratios and the risk of venous thrombosis.

We studied the HR2 haplotype of the factor V gene in a case-control study for venous thrombosis including 474 patients with a first deep-vein thrombosis and 474 age- and sex-matched healthy controls (Leiden Thrombophilia Study, LETS). We investigated both the original His1299Arg (A4070G) polymorphism and the Met385Thr (T1328C) polymorphism. This latter polymorphism, located in exon 8 (heavy chain), is always present in the HR2 haplotype, but also occurs on its own in a His1299 (wt) background. The HR2 haplotype was not associated with an increased risk of venous thrombosis (OR = 1.2, 95% confidence interval: 0.8-2.0). We did not find an association between the HR2 haplotype and a reduced sensitivity for activated protein C (APC) in non-carriers of factor V Leiden (FVL). However, in compound heterozygous FVL/HR2 carriers the sensitivity for APC was reduced. The HR2 haplotype was also associated with reduced factor V antigen levels in both patients and controls. Sequence analysis of the promoter region of factor V in HR2 homozygotes did not reveal any sequence variations that could explain the reduced FV levels. Our results show that the HR2 haplotype is not associated with an increased risk of venous thrombosis or with a reduced sensitivity for APC in non-FVL carriers. However, the HR2 haplotype is associated with a reduced sensitivity for APC in carriers of FVL and with reduced factor V antigen levels.