Lp(a)-Associated Oxidized Phospholipids in Healthy Black and White Participants in Relation to apo(a) Size, Age, and Family Structure.

Background Lp(a) (lipoprotein(a)) is the major lipoprotein carrier of oxidized phospholipids (OxPL) and this function mediates Lp(a) atherogenicity. However, the relationship between OxPL, Lp(a), and genetic and biological characteristics remains poorly understood. We assessed the relationship between Lp(a)-bound OxPL, apolipoprotein(a) (apo(a)) size, age, and family structure in 2 racial groups. Methods and Results Healthy Black and White families were recruited from the general population (age: 6-74 years, n=267). OxPL and Lp(a) levels were assayed enzymatically; apo(a) isoform, LPA allele sizes, and allele-specific Lp(a) levels were determined. Lp(a)-OxPL levels did not differ significantly by racial and age groups. Lp(a)-OxPL levels were associated with total plasma Lp(a) in all participants and in race-specific analyses. Further, OxPL levels were significantly associated with allele-specific Lp(a) levels carried by the smaller apo(a) size in all participants (ß=0.33, P=0.0003) as well as separately for Black (ß=0.50, P=0.0032) and White (ß=0.26, P=0.0181) participants. A significant association of OxPL with allele-specific Lp(a) levels for larger apo(a) sizes was seen only in Black participants (ß=0.53, P=0.0076). In this group, Lp(a)-OxPL levels were also heritable (h2=0.29, P=0.0235), resulting in a significant interracial difference in heritability between Black and White people (P=0.0352). Conclusions Lp(a)-OxPL levels were associated with allele-specific Lp(a) level carried on smaller apo(a) sizes and among Black participants also for larger apo(a) sizes. The heritability estimates for Lp(a)-bound OxPL differed by race.