Genetics of CVD Risk Factors in Samoans

BACKGROUND:

Modernizing Samoans are characterized by high levels of certain cardiovascular disease (CVD) risk factors such as extreme adiposity and high prevalences of obesity and hypertension. However, lipid levels in Samoans such as total cholesterol and high density lipoprotein (HDL) cholesterol are not consistent with their obesity and not always consistent with ecological measures of modernization.

DESIGN NARRATIVE:

The cross-sectional study used serum lipid and lipoprotein and dietary data collected in 1994 and 1995 in American and Western Samoa to compare the American and Western Samoans. Quantitative determinations were made of lipid and apolipoprotein levels differences between the two groups. Estimates were made of the effects of dietary intake, body size, and smoking on lipid and apolipoproteins. Cross-sectional analyses were performed on genetic factors influencing lipid and lipoprotein levels. Statistical analyses were conducted to test hypotheses about gene-environment interactions and gene-gene interactions in polynesians from American Samoa and Western Samoa.

Diet, physical activity and body size vary with exposure to the influences of economic modernization and the adoption of non-traditional behaviors. Although adiposity and its central distribution, insulin, blood pressure and dietary cholesterol increase from Western Samoa to American Samoa, saturated fat intakes due to coconuts and cigarette smoking are greater in Western Samoa. Thus, modernization does not produce simple unilineal changes in risk factors. The investigators examined very specific hypotheses, based on the cross-sectional data collected in 1994 and 1995, about the influence of genes on lipids, about genetic interactions on lipids and about concrete environmental and specific gene interactions on lipid outcomes.