Promoter polymorphisms in the plasma glutathione peroxidase (GPx-3) gene: a novel risk factor for arterial ischemic stroke among young adults and children.
OBJECTIVE
Plasma glutathione peroxidase (GPx-3)-deficiency increases extracellular oxidant stress, decreases bioavailable nitric oxide, and promotes platelet activation. The aim of this study is to identify polymorphisms in the GPx-3 gene, examine their relationship to arterial ischemic stroke (AIS) in a large series of children and young adults, and determine their functional molecular consequences.


METHODS
We studied the GPx-3 gene promoter from 123 young adults with idiopathic AIS and 123 age- and gender-matched controls by single-stranded conformational polymorphism and sequencing analysis. A second, independent population with childhood stroke was used for a replication study. We identified 8 novel, strongly linked polymorphisms in the GPx-3 gene promoter that formed 2 main haplotypes (H1 and H2). The transcriptional activity of the 2 most prevalent haplotypes was studied with luciferase reporter gene constructs.


RESULTS
The H2 haplotype was over-represented in both patient populations and associated with an independent increase in the risk of AIS in young adults (odds ratio=2.07, 95% CI=1.03 to 4.47; P=0.034) and children (odds ratio=2.13, 95% CI=1.23 to 4.90; P=0.027). In adults simultaneously exposed to vascular risk factors, the risk of AIS approximately doubled (odds ratio=5.18, 95% CI=1.82 to 15.03; P<0.001). Transcriptional activity of the H2 haplotype was lower than that of the H1 haplotype, especially after upregulation by hypoxia (normalized relative luminescence: 3.54+/-0.32 versus 2.47+/-0.26; P=0.0083).


CONCLUSIONS
These findings indicate that a novel GPx-3 promoter haplotype is an independent risk factor for AIS in children and young adults. This haplotype reduces the gene's transcriptional activity, thereby compromising gene expression and plasma antioxidant and antithrombotic activities.
Voetsch
Barbara
B
Whitaker Cardiovascular Institute and Evans Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
Jin
Richard C
RC
Bierl
Charlene
C
Benke
Kelly S
KS
Kenet
Gili
G
Simioni
Paolo
P
Ottaviano
Filomena
F
Damasceno
Benito P
BP
Annichino-Bizacchi
Joyce M
JM
Handy
Diane E
DE
Loscalzo
Joseph
J
D000328:Adult; D000975:Antioxidants / Q000378:metabolism; D001777:Blood Coagulation / Q000235:genetics; D002545:Brain Ischemia / Q000097:blood / Q000201:enzymology / Q000235:genetics*; D002648:Child; D004252:DNA Mutational Analysis; D004789:Enzyme Activation / Q000235:genetics; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D005787:Gene Frequency; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D005979:Glutathione Peroxidase / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009154:Mutation / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012307:Risk Factors; D020521:Stroke / Q000097:blood / Q000201:enzymology / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics
D000975:Antioxidants; D005819:Genetic Markers; C486484:GPX3 protein, human; D005979:Glutathione Peroxidase