Journal of Human Hypertension (2000) 14, 369–372
 2000 Macmillan Publishers Ltd All rights reserved 0950-9240/00 $15.00
www.nature.com/jhh
REVIEW ARTICLE
Genes, coagulation and cardiovascular
risk
MB Donati, F Zito, A Di Castelnuovo and L Iacoviello
‘Angela Valenti’ Laboratory of Genetic and Environmental Risk Factors for Thrombotic Disease,
Department of Vascular Medicine and Pharmacology, Istituto di Ricerche Farmacologiche Mario Negri,
Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
Coronary artery disease (CAD) is a multifactorial disease influenced by both genetic and environmental
determinants. Coagulation activation plays a key role in
thrombus formation and variation in its factors has been
associated with the risk of CAD. The levels of these factors are genetically determined and polymorphisms in
their genes can also be responsible for disease development. Three polymorphic alleles of coagulation factor
VII (FVII) gene have been associated with a protective
effect on the risk of familial myocardial infarction. Their
distribution in Europe covaries across populations with
the rate of myocardial infarction mortality, being higher
in countries (like Italy, Spain, Greece) at low risk. These
polymorphisms are major determinants of FVII variability in humans. They can also determine the response
of FVII to environmental stimuli. Indeed, they modulate
the association between triglycerides or smoking and
FVII, while a gender-dependent regulation of FVII, probably related to sexual hormones, has also been
described. Interestingly, lowering the plasma levels of
FVII with low dose warfarin to the same low normal
range as that associated with the ‘protective’ genotypes,
results in protection against ischaemic heart disease,
reducing mortality in high risk men.
Journal of Human Hypertension (2000) 14, 369–372
Keywords: coronary artery disease, genetic polymorphisms; factor VII; thrombosis
Introduction
Coronary artery disease is mainly responsible for
mortality and morbidity in Europe. In Italy, approximately every 10 min a new case of myocardial
infarction is recorded, and one out of three of these
cases will die from myocardial infarction.
Atherosclerosis is the major cause of coronary
artery disease, however, it can be considered as a
benign disease in the absence of thrombosis. A
thrombus growing chronically or acutely on an
atherosclerotic lesion is, indeed, the pathogenetic
mechanism of coronary occlusion. Since the coagulation system plays a pivotal role in thrombus
formation, changes in these factors are particularly
relevant to the development of ischaemic cardiovascular diseases. The coagulation process is a ‘cascade’ of events that leads, through amplification of
enzymatic reactions, to the formation of thrombin
(Figure 1). The ‘cascade’ is started from the prompt
binding of circulating factor VII to tissue factor
locally produced by damaged endothelial cells
and/or infiltrating macrophages, ie, at the level of an
atheromatous plaque. The complex factor VII-tissue
factor activates factor X in factor Xa, that continues
the cascade in the presence of factor V, by activating
Correspondence: Dr Licia Iacoviello, ‘Angela Valenti’ Laboratory
of Genetic and Environmental Risk Factors for Thrombotic Disease, Department of Vascular Medicine and Pharmacology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro, Italy.
E-mail: [email protected]
Figure 1 Schematic representation for the activation of blood
coagulation in vivo.
prothrombin into thrombin, the specific enzyme that
converts fibrinogen into insoluble fibrin.
Genetic determinants of clotting factors
In the last decade, several epidemiological studies
have shown that changes in the blood levels of
coagulation factors are associated with the risk of
cardiovascular disease.1–3 The aggregation of acute
myocardial infarction (AMI) in families and the
observation that the blood levels of parameters considered as risk factors for AMI are genetically
Genes, coagulation and cardiovascular risk
MB Donati et al
370
determined, generated the hypothesis that the susceptibility to atherothrombotic disease could also be
determined by genetic factors.4,5 Recently, it has
been shown that the levels of factors related to cardiovascular disease can be genetically determined.6
In particular, common variations (or polymorphisms) in the genes coding for coagulation/
fibrinolysis factors can contribute to their variability
in blood within their normal range of distribution.7,8
Since the levels of some haemostatic factors have
been associated to the risk of myocardial infarction,
polymorphisms in genes related to them could also
contribute to the risk of the disease. Moreover, it
appears more and more evident that the genetic
background for a specific locus, besides a direct
association with the risk of the disease, should
modulate, by amplification or reduction, the effect
of environmental factors or dysmetabolic disorders
on the risk of cardiovascular disease.
R353Q polymorphism, the −323 0/10 bp promoter
has also been demonstrated to be functionally relevant; the rare insertion allele 10/bp, indeed,
reduced the promoter activity, as compared to the
common allele, in transfection experiments.17
Therefore, it is conceivable that the promoter polymorphism, due to its functionality and strong linkage disequilibrium with the R353Q polymorphism,
could also contribute to the effect of FVII genotype
on the risk of MI, or even be the main determinant
of the effect. In fact, gene–gene interactions could
be of fundamental importance in the regulation of
FVII levels; recently, in a study on a normal Italian
population we found that the effect of the rare 10/bp
alleles in lowering FVII levels was significatively
stronger in the presence of the H7 allele of the HVR4
polymorphism.14 Needless to say, it is nearly
impossible to establish in epidemiological studies,
the relative importance of different polymorphisms
in regulating clinical phenotypes.
Modulation of coagulation factor VII:
gene/gene and gene/environment
interactions
Factor VII polymorphisms and the risk of
myocardial infarction
Blood levels of coagulation factor VII (FVII) are genetically determined. Three common polymorphisms
(R353Q in exon 8, HVR4 in intron 7 and −323
0/10 bp in position −323 of the promoter region) in
factor VII gene have been described and reported to
be associated with either coagulant factor VII, activated factor VII or mass factor VII levels.9,10 Factor
VII polymorphisms may also influence the association of plasma F VII with trygliceride levels;11 a
positive relationship between F VII and triglyceride
levels is present in carriers of the R allele-variants
but not of the Q allele-variants. These findings suggest that subjects carrying the Q allele-variant of F
VII are protected from the activation of F VII in
response to dietary fat intake. Indeed, the absolute
and the percentual increase in F VII activation after
a fat-rich meal is higher in subjects with the RR
genotype than in carriers of the Q allele.12
A gender-dependent genetic regulation of F VII,
probably related to sexual hormones, is also supported by the observation that the postmenopausal
increase in F VII:c was present only in women
homozygous for the R allele, and not in those carrying the Q allele.13 Furthermore, the effect of HVR4
and −323 0/10 bp polymorphic loci are genderdependent showing an effect in males but not in
females.14
One of the mechanisms which could explain the
effect of dietary fat on F VII involves the interaction
with triglyceride-rich lipoproteins (VLDL). Indeed,
it has been described that the binding of F VII to
VLDL can prolong its half-life and enhances the process of F VII activation.15 The amino acid substitution Arg/Gln may alter this interaction and determines a decreased activation of F VII. However, a
direct effect of this polymorphism on F VII antigen
levels could also be proposed as a working hypothesis; recently, in transient transfection assays with
F VII cDNA containing the base substitution, it has
been shown that the Q allele determined a defective
secretion of the molecule from the cells.16 Beside the
Studies conducted in Italy in the framework of the
GISSI (Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto) collaboration18 have highlighted
the relationship between genetic polymorphisms
and the risk of MI. In a case-control study on
patients with a family history of thrombosis, it has
been shown that the alleles Q and H7 of R353Q and
HVR4 polymorphisms of factor VII gene had a protective effect on the risk of MI and were associated
with relatively low levels of factor VII.19 The presence of one of these alleles reduced by about 50%
the risk of myocardial infarction; moreover, the risk
was reduced four and 11 times, respectively, in subjects homozygous for the H7 and the Q allele, and
more than 16 times in double homozygotes. The
effect of the two alleles was independent and was
possibly mediated by their effect on F VII activity
levels (Table 1). The effect of the ‘protective’ allele
Q was particularly evident in smokers.20 Indeed, the
risk of MI induced by smoking, although still significant, was much less so in subjects carrying the
Q353 allele (Figure 2). However, despite the presence of a ‘natural protection’, smoking still doubled
the risk of MI even in Q353 carriers. Like air-bags
in a car, ‘protective’ factors appear not to be necessary if driving style is safe and no accident occurs.
Air-bags show their life-saving effect, however, in
the case of hazardous driving leading to a crash, but
carrying air-bags should not prevent people from
driving carefully.
The frequency of the ‘protective’ alleles of factor.
VII gene in the general Italian population was 21.4%
and 35.6%, respectively, for R353Q and HVR4 polymorphisms. In both cases, it was significantly higher
than that found in northern Europe populations,
such as in The Netherlands, Denmark and the
United Kingdom, in agreement with the higher rate
of MI mortality in such countries as compared to the
south European populations.8,10
Taken together with other protective factors
present in southern Europe, such as components of
Journal of Human Hypertension
Genes, coagulation and cardiovascular risk
MB Donati et al
Table 1 Frequency of HVR4 and R353Q polymorphisms of coagulation factor VII in the Italian population and their association with
the risk of myocardial infarction
Polymorphism
Allele/genotype
Frequency
HVR4
R353Q
HVR4
R353Q
HVR4/R353Q
H7
Q
H7H7
QQ
H7H7/QQ
35.6
21.4
13.8
4.5
3.1
Odds ratio (95% CI)
0.52
0.58
0.22
0.08
0.06
(0.33–0.81)
(0.33–1.0)
(0.08–0.63)
(0.01–0.91)
(0.01–0.08)
371
(Reduction)
(50%)
(50%)
(4 times)
(11 times)
(16 times)
be found in about one out of three to five Italian subjects through genetically determined lower factor VII
levels; in those subjects not carrying the protective
genotypes, but having other known risk factors,
lower factor VII levels might be achieved by lowdose warfarin. Would this old anticoagulant drug
offer an effective prevention against MI and possibly
other vascular ischaemic disease, in the absence of
an increased haemorragic risk?22
Perspectives towards a pharmacogenetic
approach
Figure 2 Odds ratios (and 95% Confidence Interval) for familial
myocardial infarction according to smoking habits and R/Q353
coagulation factor VII polymorphism. Never smoked carrying the
RR353 genotype is the reference group (modified from Thromb
Haemost 1999; 81: 658).20
the mediterranean diet, these findings can help
explaining the North–South gradient in MI mortality
in Europe, and support the protective role of these
polymorphisms in the development of the disease.
The patients with MI included in the case-control
study, have been selected from the GISSI-2 study
population on the basis of their family history of
thrombosis, ie, the presence of at least one firstdegree relative with MI and/or stroke before the age
of 65 years.5,21 The patients were selected in 52 Coronary Care Units, distributed in 15 regions, all over
Italy, in specialised centres as well as in general hospitals, in larger as well as in smaller cities, so that
the population collected was really representative of
our country and the results obtained reasonably
applicable to all the Italians.
The possibility to have access to a large database
of patients with MI allowed the selection of a very
homogeneous group of patients over 45 years and
with a family history of thrombosis. The latter condition was selected because genetic variants related
to the development of thrombosis should be found
more frequently in these patients than in patients or
controls without a family history.
These findings add further evidence for the
involvement of factor VII in the pathogenesis of MI
and offer new tools for innovative or more selective
strategies in the prevention and therapy of cardiovascular disease. Protection from the risk of MI may
An answer to this interesting question has been provided only few weeks after the publication of the
factor VII polymorphism study. The Thrombosis
Prevention Trial,23 conducted in the UK, by the
Medical Research Council’s General Practice
Research Framework, has reported that low-intensity oral anticoagulant therapy (average 4.1 mg warfarin daily) confers protection against ischaemic
heart disease, reducing mortality in high-risk men.
Low-dose aspirin was also effective, but only in nonfatal events, suggesting that the two treatments protected different high-risk subjects. The plasma levels
of factor VII obtained with low dose warfarin were
in the same low-normal range (60–80%) as those
associated with the ‘protective’ genotypes. Therefore, the identification of subjects carrying the ‘protective’ factor VII genotypes could help identifying
subgroups of subjects who might differentially benefit from different treatments.
Therefore, it is conceivable that in the planning of
future primary or secondary prevention trials, genotyping of the subjects may contribute to treat with
higher efficacy a relatively smaller population of
subjects. Genotyping a large number of people is
still quite expensive, although it is technically easy
and provides results which are not subjected, as in
biochemical tests, to the day-to-day variability or to
environmental modulation. The cost-effectiveness
of genotyping could be weighed against the possibility of markedly reducing the size of future trials.
Acknowledgements
This work was supported in part by the Italian
National Research Council (CNR, Rome, Italy). Progetto Strategico ‘Myocardial Infarction’ ctr. n.
970054674. Francesco Zito is the recipient of a
Mario Negri Institute ‘Alumni Association’ fellowship. Augusto Di Castelnuovo is the recipient of a
fellowship from the Centro di Formazione e Studi
Journal of Human Hypertension
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372
per il Mezzogiorno (FORMEZ, Progetto Speciale
‘Ricerca Scientifica Applicata nel Mezzogiorno’).
12
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