B. Horejsi et al., The independent correlation of the impact of lipoprotein(a) levels and apolipoprotein E polymorphism on carotid artery intima thickness, INT ANGIOL, 19(4), 2000, pp. 331-336
Background. Apolipoprotein E (apoE) plays a key role in lipoprotein metabol
ism. It occurs in three isoforms E2, E3 and E4. These isoforms have differe
nt impacts on plasma lipoprotein levels. The allele, or gene, coding apoE4
is considered a candidate for premature atherosclerosis development while t
he apoE2 gene is assumed to be protective. Lipoprotein(a) is also atherogen
ic and its increased plasma concentration is presumed to be an independent
risk factor for premature atherosclerosis. Lipoprotein(a) is a protein depo
siting directly into the atheromatous plaques, enhancing cholesterol oxidat
ion, competitively inhibiting plasminogen formation and thus having a proth
rombogenic effect. The aim of our study was to establish a relationship bet
ween common carotid artery intima thickness and two independent risk factor
s, apoE polymorphism and elevation of plasma lipoprotein(a) levels.
Methods. A cross-sectional study was performed on 114 patients who were ref
erred to the lipid clinic for primary hyperlipoproteinaemia The patients re
ceived no treatment prior to examination. Plasma levels of total cholestero
l, triglycerides, HDL-cholesterol, LDL-cholesterol, apoA, apoB, lipoprotein
(a) and the apoE genotype were determined and the carotid artery intima thi
ckness was measured using ultrasonography.
Results. The relative frequencies of apoE2, E3 and E4 were 0.049, 0.830 and
0.121. The equality of carotid intima thickness was tested using the Krusk
al-Wallis test. Medians of intima thickness in a subgroup with the allele E
2 were 0.72 mm, in a subgroup with the E3/E3 genotype 0.70 mm and in a subg
roup with the E4 allele 0.80 mm. The relationship between carotid intima th
ickness and lipoprotein(a) levels was tested using Spearman's correlation c
oefficient.
Conclusions. No statistically significant differences of carotid intima thi
ckness among subgroups divided according to their apoE genotype were found.
No relationship between carotid intima thickness and lipoprotein(a) levels
was found. On the contrary a close relationship between carotid intima thi
ckness and age and also some of the plasma lipid Variables was recorded usi
ng the method of multivariate linear regression.