Bilirubin and UGT1A1*28, are not associated with lower risk for ischemic stroke in a prospective nested case-referent setting
(English)Article in journal (Refereed) Submitted
Background: Bilirubin, an antioxidant, has been associated with reduced cardiovascular disease risk. A major cause of elevated plasma bilirubin is the common UGT1A1*28 promoter polymorphism in the gene of the bilirubin-conjugating enzyme UDP-glucuronosyltransferase-1A1, which reduces transcription by 70%. Earlier studies reporting a protective effect of bilirubin on stroke, have not included analysis of UGT1A1*28. The purpose of this study is to investigate if bilirubin and UGT1A1*28 are protective against ischemic stroke in a prospective case-referent setting.
Methods: Cases with first-ever ischemic stroke (n=231; median lag time 4.9 years), and 462 matched referents from the The Northern Sweden Health and Disease Study Cohort were included. Plasma bilirubin was measured and UGT1A1*28 was analyzed by fragment analysis.
Results: Plasma bilirubin was lower in cases than in referents, but the difference reached significance only for women. The UGT1A1*28 polymorphism (allele frequency 30%), showed a strong gene-dose relationship with bilirubin levels both among cases and referents, but was not associated with risk for stroke. Among multiple other variables analysed the strongest correlation with bilirubin was found for plasma iron.
Conclusions: There was no evidence for a protective effect of the UGT1A1*28 polymorphism against stroke and consequently neither for bilirubin. The findings suggest that other factors influencing the risk for stroke also might affect bilirubin levels.
acute ischemic stroke, epidemiology, risk factor, bilirubin, UGT1A1*28
Cardiac and Cardiovascular Systems Public Health, Global Health, Social Medicine and Epidemiology
Research subject Clinical Chemistry
IdentifiersURN: urn:nbn:se:umu:diva-33753OAI: oai:DiVA.org:umu-33753DiVA: diva2:317821