Lipoprotein(a) concentrations and apolipoprotein(a) isoform distribution in a Zimbabwean population

OBJECTIVE: To determine serum lipoprotein(a)[Lp(a)] concentrations and apolipoprotein(a)[apo(a)] phenotypes in a Zimbabwean population. DESIGN: Cross sectional study. SETTING: Blood Transfusion Services, Harare, Zimbabwe. SUBJECTS: 84 black and 40 white blood donors. MAIN OUTCOME MEASURES: Lp(a) concentrations and apo(a) phenotypes. RESULTS: The mean and median values for Lp(a) concentrations were 506 and 350 mg/L for the black subjects and 278 and 142 mg/L for the white subjects (p < 0.005). The frequency distributions of Lp(a) concentrations for both populations were skewed to the right. The frequency distribution of apo(a) size, expressed as the number of kringle IV repeats, was determined. Comparison of the frequency distribution plots showed very similar isoform distributions between the two groups. The documented inverse relationship between apo(a) size and Lp(a) concentration was observed in the white population. CONCLUSION: The Lp(a) levels in the black population were two to three fold higher than in the white population whilst no differences in apo(a) phenotype distribution were noted. This suggests that environmental and metabolic factors may be responsible for the elevated Lp(a) levels observed in blacks. Thus different pathological thresholds may have to be established for elevated serum Lp(a) levels to be used as a risk marker for coronary heart disease in black populations.