Summary
We investigated the association between fibrinogen levels and a HaeIII restriction
fragment length polymorphism located at −453 bp from the start of transcription of
the β fibrinogen gene. 292 healthy men aged 45 to 69 years, recruited from general
practices throughout Britain, were studied. None had a history of ischaemic heart
disease. 41.1% (120) were smokers and fibrinogen levels were higher in this group.
The frequency of the noncutting allele (designated H2) was 0.19 and was the same in
smokers and non-smokers. The H2 allele was associated with elevated levels of fibrinogen
in both smokers and non-smokers and the effect of genotype was similar in both groups.
After smoking, HaeIII genotype was the strongest predictor of fibrinogen levels and
explained 3.1% of the variance in fibrinogen levels. These results confirm earlier
studies that variation at the fibrinogen locus contributes to the between-individual
differences in plasma fibrinogen level.