In 76 supposedly healthy families, we investigated the familial resemb
lance of left and right carotid intima-media thickness (IMT) measured
by B-mode ultrasonography and the impact of the common apolipoprotein
E (apo E) polymorphism and the insertion/deletion polymorphism of the
angiotensin-converting enzyme (ACE). Genetic factors accounted for abo
ut 30% of IMT variation. The insertion/deletion ACE polymorphism did n
ot influence carotid IMT, whereas apoE polymorphism explained about 1.
5% of only right carotid IMT variability independently of cholesterol
levels. The apo epsilon 2 and apo epsilon 4 alleles were associated wi
th lower right carotid IMT than was the apo epsilon 3 allele. We concl
ude that genetic factors strongly contribute to IMT variability in hea
lthy people and that the apo E polymorphism may be one of these factor
s.