Metabolic and anthropometric determinants of serum Lp(a) concentrations and Apo(a) polymorphism in a healthy Arab population

Abstract

BACKGROUND: Blood lipoprotein(a) Lp(a) concentrations are an important risk factor for atherosclerosis. The basis for this atherogenic property of Lp(a) and the factors that influence its cross-population levels, however, remain poorly understood.

OBJECTIVES: To investigate the relationship between serum Lp(a) and metabolic and anthropometric parameters in a healthy Kuwaiti population.

DESIGN: Cross-sectional study.

SUBJECTS: 177 (72 male, 105 female) randomly recruited healthy Kuwait Arabs aged 17–60 y

MEASUREMENTS: Metabolic parameters in serum: Lp(a), apo(a) phenotypes, lipids and lipoproteins, glucose and urate. Anthropometric parameters: body mass index (BMI) and waist:hip‐ratio (WHR).

RESULTS: The distribution of Lp(a) concentrations was positively skewed (median 153 mg/l, range 0–1086). Women had higher concentrations–(194, 0–1086) than men (117, 0–779), P=0.069. Lp(a) and insulin concentrations were significantly higher when the men and women were obese. In all subjects, there were significant correlations between Lp(a) and BMI (r=0.23), total cholesterol (TC) (r=0.17) and LDL (r=0.20). Lp(a) correlated only with glucose in men (r=0.28). In women it correlated with age (r=0.20), BMI (r=0.30), BP (r=0.20), TC (r=0.20) and LDL (r=0.26). Multivariate analyses confirmed BMI and low-density lipoprotein (LDL) as the significant determinants of serum Lp(a). On apo (a) phenotyping, 114 (67%), 51 (30%) and 6 (4%) had single, double and null phenotypes respectively. The isoforms and their corresponding kringle IV repeat numbers were: F (14 repeats in 3%, mean Lp(a) 497 mg/l); S1 (19 repeats in 14%, mean 245 mg/l); S2 (23 repeats in 16%, mean 264 mg/l); S3 (27 repeats in 35%, mean 236 mg/l); and S4 (35 repeats in 28%, mean 235 mg/l).

DISCUSSION AND CONCLUSION: The results from the Kuwaiti population studied suggest that: (1) serum Lp(a) concentrations and distribution are similar to the pattern in Caucasians and Asians but not African–Americans or Africans; (2) serum Lp(a) is variably influenced by BMI and LDL–the impact of either factor differs between the sexes; (3) there is a high frequency of the single-banded phenotype; (4) contrary to reports in some Caucasian and Asian populations, there is no simple relationship between kringle IV repeat numbers and plasma Lp(a) concentrations.