Plasminogen activator inhibitor-1 4G/5G polymorphism and risk of stroke: replicated findings in two nested case-control studies based on independent cohorts.
OBJECTIVE
Impaired fibrinolytic function secondary to elevated plasminogen activator inhibitor-1 (PAI-1) levels has been implicated in ischemic stroke. PAI-1 levels are determined by genetic factors and environmental factors, triglyceride levels in particular. The aim of this study was to investigate the common functional 4/5 guanosine (4G/5G) polymorphism in the promoter region of the PAI-1 gene and the risk of stroke.


METHODS
A nested case-control study design was applied, using baseline data for 2 independent cohorts obtained at population-based surveys in northern Sweden. In study A, there were 113, and in study B, there were 275 individuals without major concomitant disease at baseline who later experienced a first-ever stroke. Blood samples obtained at baseline were analyzed for potential risk factors, including the 4G/5G polymorphism of the PAI-1 gene.


RESULTS
The 4G allele of the PAI-1 polymorphism was associated with an increased risk of future ischemic stroke in both studies (odds ratio [OR] of 4G homozygosity, 1.87; 95% CI, 1.12 to 3.15 in study A; OR of 4G homozygosity, 1.56; 95% CI, 1.12 to 2.16 in study B). Individuals with the combination of hypertriglyceridemia and 4G homozygosity were at the greatest risk of developing stroke. Multiple logistic regression analysis identified 4G homozygosity, systolic blood pressure, and diabetes as independent predictors of ischemic stroke.


CONCLUSIONS
Identical findings in 2 independent studies strongly suggest a true and clinically important association between PAI-1 4G/5G genotype and risk of future ischemic stroke. The observed modification of the genotype effect by triglycerides may be interpreted as a gene-environment interaction.
Wiklund
Per-Gunnar
PG
Department of Public Health and Clinical Medicine, Umeå University Hospital, Sweden. pg.wiklund@medicin.umu.se
Nilsson
Lennart
L
Ardnor
Sofie Nilsson
SN
Eriksson
Per
P
Johansson
Lars
L
Stegmayr
Birgitta
B
Hamsten
Anders
A
Holmberg
Dan
D
Asplund
Kjell
K
D000328:Adult; D000368:Aged; D000483:Alleles; D001794:Blood Pressure; D016022:Case-Control Studies; D015331:Cohort Studies; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007511:Ischemia; D008875:Middle Aged; D016017:Odds Ratio; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics* / Q000502:physiology; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D012044:Regression Analysis; D012306:Risk; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000235:genetics*; D013548:Sweden; D013997:Time Factors; D014158:Transcription, Genetic; D014280:Triglycerides / Q000378:metabolism
D017395:Plasminogen Activator Inhibitor 1; D014280:Triglycerides