Relationship between apo(a) length polymorphism and lipoprotein(a) concentration in healthy Ivorian subjects with single or double apo(a) isoforms.

Objectives: To determine the relationship between apo(a) size and Lp(a) concentration in healthy Ivorian subjects.

Methods: Serum Lp(a) was measured by immunonephelometry and electroimmunodiffusion, and apo(a) size determined by immunoblotting.

Results: Both assay methods provided comparable information. Lp(a) concentrations showed a non-Gaussian distribution and skewed towards higher values. Apo(a) isoform size distribution exhibited three frequency peaks at 18, 22 and 25 kringles. Single and double apo(a) isoforms were detected in 36% and 64% of subjects, respectively. Lp(a) values were higher in subjects with double isoforms, the major isoform being of lower size. An inverse correlation between apo(a) size and Lp(a) concentration was found, apo(a) size accounting for more than 30% of Lp(a) concentration in "single-band" group, whereas being weaker in "double-band" group. Low size isoforms were associated with higher Lp(a) concentrations, high size isoforms with higher variability.

Conclusions: Lp(a) concentrations were inversely correlated to apo(a) size. This study has shown the relationship between apo(a) size and Lp(a), the influence of apo(a) size varying according to the phenotype. Apo(a) "double isoform" phenotype confers elevated levels to Lp(a) in healthy Ivorian subject.