Ethnic differences in the association between lipid metabolism genes and lipid levels in black and white South African women.

OBJECTIVE: Dyslipidaemia can lead to the development of atherosclerosis and cardiovascular disease (CVD), however its prevalence has been shown to differ between ethnic groups in South Africa (SA). Therefore the aim of this study was to investigate ethnic differences in the association between serum lipid levels and polymorphisms within genes involved in lipid metabolism in black and white SA women. METHODS: In a convenient sample of 234 white and 209 black SA women of Xhosa ancestry, body composition (DXA) and fasting serum lipids were measured. Participants were genotyped for the cholesteryl ester transfer protein (CETP, rs708272, B1/B2), lipoprotein lipase (LPL, rs328, S/X), hepatic lipase (LIPC, rs1800588, C/T) and proprotein convertase subtilisin/kexin type 9 (PCSK9, rs28362286, C/X) polymorphisms. RESULTS: Compared to white women, black women had lower concentrations of serum total cholesterol (TC, P < 0.001), low density lipoprotein cholesterol (LDL-C, P < 0.001), high density lipoprotein cholesterol (HDL-C, P < 0.001) and triglycerides (TG, P < 0.001). There were significant differences in the genotype and allele frequency distributions between black and white women for the LPL S/X (P < 0.001), PCSK9 C679X (P = 0.002) and LIPC 514C/T (P < 0.001) polymorphisms. In black women only, there were genotype effects on serum lipid levels. Specifically, women with the LPL SX genotype had lower TC and LDL-C and higher HDL-C concentrations than those with the SS genotype and women with the CETP B2 allele had lower LDL-C concentrations than those with the B1B1 genotype. CONCLUSION: Polymorphisms within the LPL and CETP genes were associated with a more protective lipid profile in black, but not white SA women. This supports the hypothesis that the more favorable lipid profile of black compared to white SA women is associated with polymorphisms in lipid metabolism genes, specifically the LPL and CETP genes.

The role of adipose tissue in insulin resistance in women of African ancestry.

Women of African ancestry, particularly those living in industrialized countries, experience a disproportionately higher prevalence of type 2 diabetes (T2D) compared to their white counterparts. Similarly, obesity and insulin resistance, which are major risk factors for T2D, are greater in black compared to white women. The exact mechanisms underlying these phenomena are not known. This paper will focus on the role of adipose tissue biology. Firstly, the characteristic body fat distribution of women of African ancestry will be discussed, followed by the depot-specific associations with insulin resistance. Factors involved in adipose tissue biology and their relation to insulin sensitivity will then be explored, including the role of sex hormones, glucocorticoid metabolism, lipolysis and adipogenesis, and their consequent effects on adipose tissue hypoxia, oxidative stress, and inflammation. Finally the role of ectopic fat deposition will be discussed. The paper proposes directions for future research, in particular highlighting the need for longitudinal and/or intervention studies to better understand the mechanisms underlying the high prevalence of insulin resistance and T2D in women of African ancestry.