Type I congenital plasminogen deficiency is not a risk factor for thrombosis.

The risk of thrombosis in type I congenital plasminogen (PLG) deficiency has been suggested, but is still not confirmed. We studied 40 members of two unrelated families with this disease, and found that 21 were heterozygotes of type I congenital PLG deficiency. Three of them had thrombosis, but the other 18 had no thrombosis. The percentages of family members with no history of thrombosis up to a given age among subjects with type I congenital PLG deficiency and healthy controls were analyzed by the Kaplan-Meier method. No significant difference between the two groups was observed by the generalized Wilcoxon test (p = 0.23). These results suggest that there is no significant correlation between type I congenital PLG deficiency and thrombosis.     

The urokinase-type plasminogen activator polymorphism PLAU_1 is a risk factor for APOE-epsilon4 non-carriers in the Italian Alzheimer's disease population and does not affect the plasma Abeta(1-42) level

Sporadic Alzheimer's disease (AD) is the most frequent form of dementia in the elderly. A non-conservative polymorphism in the urokinase-type plasminogen activator gene (PLAU_1=RS2227564) has been analyzed, but data are conflicting on whether it is a risk factor for AD. To clarify whether this genetic variant modifies AD risk in the Italian population, we ran a case-control association study on 192 AD and 126 age-matched controls. We did not find any association between PLAU_1 genotype and AD in the whole AD population, but when we stratified our sample by APOE-epsilon4 status, we found a significant association between PLAU_1 genotype (C/T+T/T) and APOE-epsilon4 negative AD subjects (p=0.02, chi(2)-test). The PLAU_1 genotype did not appear to affect the plasma Abeta42 concentration. Our data support a role for PLAU_1 as an independent genetic risk factor for AD in the Italian population for those subjects who do not have the APOE-epsilon4 allele.     

The G79A polymorphism of protein Z gene is an independent risk factor for cerebral venous thrombosis

Background and purpose   Protein Z (PZ), a vitamin Kdependent protein, plays a role in inhibiting coagulation. Its plasma level or PZ gene polymorphisms have been discussed as risk factors for stroke with conflicting results reported between various studies. Only one of these polymorphisms was studied in a cohort of patients suffering from cerebral venous thrombosis (CVT). Methods   We performed a retrospective genetic study comparing 100 healthy controls to 54 patients referred to our hemostasis unit after CVT occurrence. We compared the distribution of three PZ gene polymorphisms that may influence PZ plasma levels: A-13G in the promoter and G79A in intron F were tested using previously described techniques, and we developed a technique to evaluate the G-103A in intron A. Results   The G79A polymorphism was significantly more frequent in patients than in controls (p = 0.012): the presence of at least one A allele led to an odds ratio of 2.57 with a 95 % confidence interval of 1.23–5.34. The A-13G polymorphism also showed a nonsignificant trend towards a higher prevalence in patients. Conclusion   The G79A polymorphism of the PZ gene was shown to be a new independent risk factor for cerebral venous thrombosis. Nevertheless, these results have to be confirmed by a prospective study including plasma PZ evaluation.     

A population-based study of an Italian genetic isolate reveals that mean platelet volume is not a risk factor for thrombosis

Introduction

Several studies revealed that mean platelet volume (MPV) was larger in the acute phase of arterial and venous thrombosis and predicted a poor clinical outcome. It has been suggested that MPV is a risk factor for thrombosis. However, it is unclear whether increased platelet size is a cause or a consequence of thrombosis.It was the objective of this study to verify whether MPV is a risk factor for arterial and venous thrombosis.

Methods

We search for associations between platelet parameters and thrombosis by a population-based study in 11,084 inhabitants of an Italian genetic isolate characterized by wide variability of platelet parameters. To validate this methodology of investigation, we also evaluated whether it was able to identify several well known thrombotic risk factors in the study population.

Results

Statistical analysis confirmed that male gender, ageing, hypertension, high total cholesterol, low HDL cholesterol, diabetes, obesity and smoking were risk factors for arterial thrombosis, while alcohol consumption had a protective effect. Female gender, ageing, pregnancy, estroprogestinic treatment, obesity, varicose veins were associated with venous thrombosis. At variance, MPV and platelet count were unrelated to previous thrombotic events. However, MPV was negatively correlated with the time since the last thrombotic event.

Conclusions

This study indicated that an epidemiologic study of a population isolate is appropriate for the identification of thrombotic risk factors, but it failed to identify such a role for MPV. Thus, we suggest that the increased MPV previously described in subjects with acute thrombosis was a consequence instead of a cause of thrombosis.     

Variable expression of presenilin 1 is not a major determinant of risk for late-onset Alzheimer's Disease

We have previously reported a significant association between early-onset Alzheimer's disease (EOAD) and an allele in the promoter of presenilin 1 (PSEN1) significantly decreasing PSEN1 expression in vitro. For late-onset Alzheimer's disease (LOAD), numerous studies have reported inconsistent associations with a PSEN1 intronic polymorphism. We therefore hypothesized that linkage disequilibrium between the intronic PSEN1 polymorphism and the functional promoter polymorphism might explain the conflicting reports in LOAD. We analysed both variations in 356 LOAD patients and 230 controls in a population-based case-control study. In addition, we re-analysed all published literature on the PSEN1 intronic polymorphism in a meta-analysis. No significant association was found with the PSEN1 intronic or promoter polymorphism in our case-control sample. In the meta-analysis no major differences between patients and controls were found for the PSEN1 intronic variation. Together, our results do not support a major role for variable expression of PSEN1 in LOAD. Received: 15 December 2000, Received in revised form: 13 March 2001, Accepted: 4 May 2001     

A genetic variation of cathepsin D is a major risk factor for Alzheimer's disease

Cathepsin D (catD) is an intracellular acid protease possibly involved in Alzheimer's disease (AD)-related neurodegeneration through cleavage of amyloid precursor protein into amyloidogenic components. We studied whether an exonic polymorphism of the catD gene (C --> T [Ala --> Val] transition at position 224), which possibly influences pro-catD secretion and intracellular maturation of the enzyme, was associated with the risk for the development of AD in 127 demented patients and 184 controls. The catD*T allele was significantly overrepresented in demented patients (11.8%) compared with nondemented controls (4.9%). Carriers of the catD*T allele had a 3.1-fold increased risk for developing AD than noncarriers. Carriers of the apolipoprotein E (ApoE) epsilon4 allele (ApoE*4) had a 3.9-fold increased risk than non-carriers. The adjusted odds ratio for subjects with the ApoE*4 and the catD*T allele was 19.0 compared with subjects with neither of these two alleles. Our data confirm the results of a recently performed pilot study in an independent sample and suggest that the catD genotype is strongly associated with the risk for AD.     

High plasma concentration of factor VIIIc is a major risk factor for venous thromboembolism

BACKGROUND: Established risk factors, including deficiencies of protein C, protein S or antithrombin and the factor V Leiden and prothrombin mutation, are present in about one third of unselected patients with venous thromboembolism. In addition to these inherited thrombophilic defects, elevated plasma levels of factor VIIIc have been suggested to be important in the pathogenesis of (recurrent) venous thromboembolism. The objective of this study was to assess the relevance of factor VIIIc plasma concentration in consecutive patients with venous thromboembolism. METHOD: We studied the prevalence of elevated plasma levels of factor VIIIc in 65 patients with a proven single episode and in 60 matched patients with documented recurrent venous thromboembolism. The reference group consisted of 60 age- and sex-matched patients who were referred for suspected venous thromboembolism, which was refuted by objective testing and long-term clinical follow-up. To minimalize the influence of the acute phase, blood was obtained at least 6 months after the thromboembolic event and results were adjusted for fibrinogen and C-reactive protein. Factor VIIIc was re-determined several years after the first measurement in a subset of patients to evaluate the variability over time. To study a possible genetic cause, a family study was done. FINDINGS: In the control, single and recurrent episode group, the prevalences of plasma levels of factor VIIIc above 175 IU/dl (90th percentile of controls) were 10% (95% CI: 4 to 21%), 19% (95% CI: 10 to 30%) and 33% (95% CI: 22 to 47%), respectively. For each 10 IU/dl increment of factor VIIIc, the risk for a single and recurrent episode of venous thrombosis increased by 10% (95% CI: 0.9 to 21%) and 24% (95% CI: 11 to 38%), respectively. Both low and high plasma levels of factor VIIIc were consistent over time (R = 0.80, p = 0.01). A family study indicated a high concordance for elevated factor VIIIc plasma concentrations among first degree family members. Adjustment for fibrinogen, C-reactive protein and known thrombophilic risk factors did not change the observed association of elevated factor VIIIc with thrombosis. INTERPRETATION: Elevated plasma levels of factor VIIIc are a significant, prevalent, independent and dose-dependent risk factor for venous thromboembolism. It also predisposes to recurrent venous thromboembolism.     

A polymorphism in the cystatin C gene is a novel risk factor for late-onset Alzheimer's disease

OBJECTIVE: To investigate whether or not a coding polymorphism in the cystatin C gene (CST3) contributes risk for AD. DESIGN: A case-control genetic association study of a Caucasian dataset of 309 clinic- and community-based cases and 134 community-based controls. RESULTS: The authors find a signficant interaction between the GG genotype of CST3 and age/age of onset on risk for AD, such that in the over-80 age group the GG genotype contributes two-fold increased risk for the disease. The authors also see a trend toward interaction between APOE epsilon4-carrying genotype and age/age of onset in this dataset, but in the case of APOE the risk decreases with age. Analysis of only the community-based cases versus controls reveals a significant three-way interaction between APOE, CST3 and age/age of onset. CONCLUSION: The reduced or absent risk for AD conferred by APOE in older populations has been well reported in the literature, prompting the suggestion that additional genetic risk factors confer risk for later-onset AD. In the author's dataset the opposite effects of APOE and CST3 genotype on risk for AD with increasing age suggest that CST3 is one of the risk factors for later-onset AD. Although the functional significance of this coding polymorphism has not yet been reported, several hypotheses can be proposed as to how variation in an amyloidogenic cysteine protease inhibitor may have pathologic consequences for AD.     

Further evidence that methylenetetrahydrofolate reductase A1298C polymorphism is a risk factor for schizophrenia

Previous work suggests that the methylenetetrahydrofolate reductase gene (MTHFR) functional polymorphism A1298C may be a risk factor for schizophrenia. In this study, the genetic association between the MTHFR A1298C polymorphism and schizophrenia was investigated in 379 patients with schizophrenia and 380 age- and sex-matched controls subjects. The results showed an association between the 1298C allele and the disorder (OR 1.39, 95% confidence interval 1.08–1.79). This provides further evidence that the MTHFR A1298C polymorphism may play a role in conferring risk for schizophrenia in the Chinese Han population.     

Paternal age is a risk factor for Alzheimer disease in the absence of a major gene

We compared the parental age at birth of patients with Alzheimer disease (AD) with that of cognitively healthy control subjects. Within 206 carefully diagnosed AD patients, two groups were distinguished according to the likelihood of carrying a major gene for AD (MGAD). This likelihood was calculated by applying a Bayesian approach which incorporates data on aggregation of the disease, age at onset, and "censoring" ages within the family. All AD patients were ranked by MGAD probability. According to the sample's quartiles, two subgroups were defined representing the 52 individuals with the lowest and the 52 with the highest MGAD probability. Age at onset of dementia, education, and apolipoprotein E ε  4 allele frequencies were not statistically different between the two groups. Fathers of patients with a low MGAD probability were significantly older (35.7±8.1 years) than fathers of both other groups (high MGAD probability 31.3±6.9 years, P =0.004; controls 32.6±6.8 years, P =0.04, n=50). The differences for mothers were less pronounced and not statistically significant. These findings suggest that increased paternal age is a risk factor for AD in the absence of a major gene, whereas increased maternal age and AD are associated only weakly and independently of genetic disposition. Received: February 23, 1998 / Revised and Accepted: May 20, 1998     

The Fc gammaRIIa polymorphism R/H131, autoantibodies against the platelet receptors GPIb alpha and Fc gammaRIIa and a risk for thromboembolism in lupus anticoagulant patients

There is a clear propensity of individuals with lupus anticoagulant (LA) for thromboembolic disease (TE). Yet, it is not clear how individuals at risk for TE can be differentiated from those who are not. The Fc gammaRIIa receptor is the only Fc receptor expressed by platelets. As platelets can be activated via this receptor, we have compared gene frequencies of the Fc gammaRIIa polymorphism R/H131 in 46 and 27 patients with (LA/TE+) and without TE (LA/TE-), respectively, in an exploratory study. Furthermore, we investigated the presence of autoantibodies against Fc gammaRIIa and/or GPIb alpha, which is in close proximity to the Fc gammaRIIa and interacts with it functionally, and a possible linkage of antibody formation to HLA class II alleles. The Fc gammaRIIa-R/R131 genotype was significantly less frequent in patients with LA compared to controls (p<0.025). These findings were due to an increased frequency of heterozygous patients in the LA/TE+ cohort (odds ratio 6.76, 95% confidence interval 1.55-62.03, p<0.008). For the first time, heterozygosity, rather than homozygosity, can be linked to disease, which may be explained by the dual function of the Fc gammaRIIa, namely binding of antibodies to platelets and thereby their activation, and, on the other hand, clearance of antibody coated platelets by the phagocyte system. There was no correlation between the presence of anti-Fc gammaRIIa or anti-GPIb alpha autoantibodies and the Fc gammaRIIa-R/H131 polymorphism, nor the incidence of TE, nor HLA class II alleles.     

Coagulation factor VII R353Q polymorphism and the risk of puerperal cerebral venous thrombosis

Puerperal cerebral venous thrombosis (CVT) is a relatively common form of stroke in young women in India. The blood coagulation factor VII (FVII) R353Q polymorphism increases the risk for venous thrombosis. Our aim was to investigate the association of FVII R353Q polymorphism with the risk of puerperal CVT. A total of 100 women with puerperal CVT and 102 age-matched women without postpartum complications were investigated. FVII R353Q genotypes were identified using restriction fragment length polymorphism analysis. Our results showed that the homozygous FVII 353QQ genotype was present in 9% and 8% of patients and controls, respectively; and 42% of patients and 31.4% of controls had the heterozygous 353RQ genotype (odds ratio = 1.55, 95% confidence interval = 0.89-2.70; p = 0.243). Our findings suggest that the FVII R353Q polymorphism is not associated with increased risk for CVT occurring during the puerperal period in Indian women.     

Association after linkage analysis indicates that homozygosity for the 46C-->T polymorphism in the F12 gene is a genetic risk factor for venous thrombosis

In a family-based study called GAIT (Genetic Analysis of Idiopathic Thrombophilia) that included a genome-wide scan we demonstrated that a polymorphism (46C-->T) in the F12 locus jointly influences variability of plasma (Factor XII) FXII levels and susceptibility to thrombotic disease. It then became germane to determine the prevalence of the 46C-->T polymorphism and its relative risk of thrombotic disease. We followed up evidence for genetic linkage with a case-control study, including 250 unrelated consecutive Spanish patients suffering from venous thrombotic disease and 250 Spanish subjects matched for sex and age as a controls. We measured FXII levels and genotyped the 46C-->T polymorphism, as well as a number of classical risk factors for thrombotic disease.We confirmed that individuals with different genotypes for this polymorphism showed significant differences in their FXII levels. Most importantly, the mutated T allele in the homozygous state (genotype T/T) was associated with an increased risk of thrombosis (adjusted OR of 4.82; 95% CI 1.5-15.6), suggesting that the polymorphism itself is an independent risk factor for venous thromboembolism. This study confirms that the 46C-->T polymorphism is a genetic risk factor for venous thrombosis in the Spanish population. In addition, our results confirm that a genome-wide scan coupled with a classical case-control association study is an extremely valuable approach to identify DNA variants that affect complex diseases.     

The deletion polymorphism in the angiotensin-converting enzyme gene is a moderate risk factor for venous thromboembolism

ACE displays potent vasoconstrictive effects, attenuation of fibrinolysis, and platelet activation and aggregation, thus possibly promoting venous thromboembolism (VTE). The ACE gene contains an insertion (I) or deletion (D) polymorphism accounting for 50% of the variation in serum ACE concentration. To evaluate the role of the I/D polymorphism in VTE, its prevalence was determined in 931 patients with VTE and 432 blood donors. The prevalence of the DD genotype was 27.6% in patients and 21.3% in controls (OR 1.4; p < 0.02). In multivariate analysis there was a trend of the DD genotype to be an independent risk factor (OR 1.4; p = 0.08). No differences in DD genotype prevalence according to exogenous risk factors were found. Coinheritance of FV G1691A, PT G20210A mutation, and PS deficiency with the DD genotype increased the relative risk of VTE. Thus, the ACE DD genotype is a moderate risk factor of hereditary thrombophilia. Exogenous risk factors did not alter the manifestation of VTE among carriers of the DD genotype, whereas coinheritance of the DD genotype with the aforementioned defects increased the risk for VTE considerably.     

Low-oestrogen oral contraceptives as a major risk factor for cerebral venous and sinus thrombosis: evidence from a clinical series

Cerebral venous and sinus thrombosis (CVST) is still considered a severe clinical problem that is difficult to diagnose and manage and is linked to a poor prognosis. Nonetheless, conventional cerebral angiography and magnetic resonance imaging (MRI), or more recently, MR angiography allow a more rapid and precise diagnosis, and prognosis has improved with the use of anticoagulant treatment.We report 23 cases of CVST consecutively admitted to the Institute of Neurology of the University of Parma during the period 1990-1997. In all cases diagnosis was confirmed by means of MRI or conventional angiography of brain vessels. Among the patients, 22 were female and 1 was male. In all patients, plasma levels of protein C, protein S, antithrombin III (ATIII) and antiphospholipid antibodies (APA) were evaluated. In 15 of 23 patients, the presence of factor V Leiden mutation was also determined, and found positive in 3 patients (20%). Of the 22 female patients, 15 (68%) were on low-oestrogen (containing less than 50 microg oestrogen) oral contraceptive (OC) treatment. This percentage of OC use by patients with CVST is much higher than that of the rest of the female Italian population. OC use was associated with the presence of factor V Leiden mutation in two cases, with a deficiency of protein C in 1 case and a deficiency of protein S in another.Whether low-oestrogen Ocs may induce cerebral thromboembolic events is an open matter. According to our data, it may be argued that Ocs, even if at low oestrogen content, represent a major risk factor for CVST. The use of Ocs, as is the case for systemic venous thromboembolic events, may further increase the risk of CVST in women carrying the factor V Leiden mutation or other inherited hyperthrombotic conditions.     

The thermolabile variant of methylenetetrahydrofolate reductase (MTHFR) is not a major risk factor for neural tube defect in American Caucasians

Mutations in the gene for methylenetetrahydrofolate reductase (MTHFR) have been implicated as a risk factor in the formation of neural tube defects. We investigated this gene in a series of 65 sporadic American Caucasians patients with lumbosacral NTD and their unaffected parents, using both case-control design and assessment of linkage disequilibrium. We found no evidence to support mutations in MTHFR as a significant risk factor for NTD in this population. Received April 28, 1997; Revised and Accepted June 20, 1997     

The E-selectin S128R polymorphism is not a risk factor for coronary artery disease in patients with diabetes mellitus type 2

AIM/HYPOTHESIS: E-selectin is thought to play a key role in the early stages of vascular disease by facilitating the attachment of leukocytes to the endothelium. Recently, a polymorphism in the E-selectin gene (S128R) has been associated with higher E-selectin levels in patients with diabetes mellitus and with premature coronary artery disease. The impact of the S128R polymorphism on the development of diabetic coronary artery disease has not been investigated yet. PATIENTS AND METHODS: A total of 254 patients recruited from the Division of Cardiology, University of Vienna with diabetes mellitus type 2 was assessed for the E-selectin S128R polymorphism by a novel mutagenic separated PCR, allowing fast and reliable genotyping without restriction enzyme digest. Ninety-five patients had a history of myocardial infarction, 90 were admitted with stable coronary artery disease whereas in 69 the presence of CAD could be excluded. RESULTS: Of all 254 individuals tested, 197 (77.6%) exhibited wildtype E-selectin 128S genotype, 54 (21.3%) were heterozygous S128R and 3 (1.1%) were homozygous for the 128R allele. In all groups the genotype frequencies did not differ significantly. No associations were found between E-selectin genotype and coronary artery disease or myocardial infarction. CONCLUSION/INTERPRETATION: In subjects suffering from diabetes mellitus type 2 the E-selectin S128R polymorphism is not associated with coronary artery disease nor with an increased risk for myocardial infarction. Thus, screening for this polymorphism is not indicated for risk assessment of CAD in patients with diabetes mellitus.