LP (A) LEVELS AND APO (A) PHENOTYPES IN URBAN BLACK SOUTH-AFRICAN MEN

Objective. To investigate the lipoprotein (a) (Lp (a)) levels and apol ipoprotein (a) (ape (a)) phenotypes in a group of urban black South Af rican men. Design. Cross-sectional design. Setting. Lead acid battery plant, East London, Eastern Cape. Participants. Blood samples from a s tudy on the association between lead and renal failure were kindly don ated for the present study and 111 of the. donors participated (K Stey n - personal communication). Outcome measures. Lp (a) levels and apo ( a) phenotypes. Results. Three groups were identified: those with norma l (< 300 U/I), intermediate (300-700 U/I) and high (> 700 U/I) plasma Lp (a) concentrations. Nine apo (a) phenotypes and 26 combinations the reof could be discerned. Apart from the single-and double-band phenoty pes described before, triple-band phenotypes were also present. As the Lp (a) values increased, the relative frequency of the single-band ph enotype decreased, whereas the relative frequency of the double-band p henotype increased. The relative frequency of the triple-band phenotyp e was highest in the group with high Lp (a) concentrations. No correla tion was evident between the size of the apo (a) isoforms and the Lp ( a) concentrations. Conclusions. Raised plasma Lp (a) levels have been associated with coronary heart disease (CHD). In addition, it has been proposed that the apo (a) gene determined plasma Lp (a) concentration s. These studies were performed using plasma from white subjects. CHD is uncommon in black South Africans. The reason may be that, given the lack of relationship between the size of the apo (a) isoforms and the Lp (a) concentrations observed in the present study, factors other th an the isoform size may determine the ip (a) levels in this particular ethnic group.