The unique lipid and lipoprotein profile of Turks is characterized primarily by very low plasma levels of high density lipoprotein cholesterol (HDL-C), specifically low levels of the protective subclasses of HDL, HDL2 and LpAl. The low HDL-C levels are associated with a 25-30% elevation of hepatic lipase activity that would be predicted to lower HDL levels. Low HDL-C levels occur in Turks living in Germany and the United States, suggesting that the reduced HDL-C levels are at least partly of genetic origin. Turkish girls and boys exhibit a marked 10-20 mg/dl drop in HDL-C levels associated with puberty, suggesting that the low HDL-C levels in Turks may reflect an ethnic difference in hormonal balance.
Data generated in the early 1990s in the original Turkish Heart Study and recently updated by a study of Turkish men and women living in istanbul indicate that the lipid profile and other risk factors for coronary heart disease have not improved in this decade. Despite their relatively low plasma total cholesterol levels, Turks have extremely low HDL-C (<40 mg/dl in 70% of men and ~50% of women) resulting in very high total cholesterol/HDL-C ratios that predict increased coronary heart disease in other populations. The 2001 National Cholesterol Education Program guidelines continue to focus on low density lipoprotein cholesterol levels and underestimate the importance of low HDL-C levels, which undoubtedly are a powerful risk factor in Turks. We suggest that guidelines for Turkey consider both low density lipoprotein cholesterol levels and total cholesterol/HDL-C ratio as thresholds for initiating lifestyle changes or drug treatment for patients with coronary heart disease risk.
Keywords: Coronary heart disease, hypercholesterolemia, high density lipoproteins, cholesterol metabolism, total cholesterol/HDL-C ratio