High serum
lipoprotein(a) (Lp(a)) concentration which is largely determined by genetic factors, mainly the
apolipoprotein(a) (
apo(a)) polymorphism, is associated with ischemic
cerebrovascular disease. The aim of this study was to investigate whether
apo(a) size was associated with
acute ischemic stroke in young adults for which causal factors often remain undetermined.
Lipid parameters, Lp(a) concentration and
apo(a)
isoform size distribution were determined in 90 young patients (37.4+/-8.7 years) with acute
cerebral ischemia, and compared to those of control subjects with similar age and sex ratio.
Apo(a) size was expressed as its apparent number of kringle 4 (Kr 4) repeats. Serum Lp(a) concentrations were significantly higher in patients than in controls (median values: 0.18 vs. 0.07 g/l, P=0.009) and were as expected inversely related to the number of kringle 4 repeats in both controls (r2=-0.61, P < 0.001) and patients (r2=-0.56, P < 0.001). However there was no difference in the
apo(a)
isoform size distributions between the two groups (median
isoform size: 27 vs. 27 Kr 4, P=0.25). Lp(a) levels were increased as well in patients with size
apo(a)
isoform < or = 22 Kr 4 as in those with
isoforms > 25 Kr 4. Multivariate analysis showed that
apo(a) phenotype did not appear as a risk factor for cerebrovascular
infarction. Thus, our results indicate that serum Lp(a) was significantly increased in young people with
ischemic stroke but fail to reveal a role of small-sized
apo(a)
isoforms in the occurrence of this event. They suggest that other factors, genetic or environmental in nature, than the
apo(a) size contribute to increase the serum Lp(a) concentrations in these young patients.