Apolipoprotein(a) size polymorphism in young adults with ischemic stroke

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 wa s to investigate whether apo(a) size was associated with acute ischemic str oke in young adults for which causal factors often remain undetermined. Lip id parameters, Lp(a) concentration and apo(a) isoform size distribution wer e 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 se x ratio. Apo(a) size was expressed as its apparent number of kringle 4 (Kr 4) repeats. Serum Lp(a) concentrations were significantly higher in patient s than in controls (median values: 0.18 vs. 0.07 g/l, P = 0.009) and were a s expected inversely related to the number of kringle 4 repeats in both con trols (r(2) = - 0.61, P < 0.001) and patients (r(2) = - 0.56, P < 0.001). H owever there was no difference in the apo(a) isoform size distributions bet ween 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 less tha n or equal to 22 Kr 4 as in those with isoforms > 25 Kr 4. Multivariate ana lysis showed that apo(a) phenotype did not appear as a risk factor for cere brovascular infarction. Thus, our results indicate that serum Lp(a) was sig nificantly increased in young people with ischemic stroke but fail to revea l a role of small-sized apo(a) isoforms in the occurrence of this event. Th ey 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. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved .