Low levels of high density lipoproteins in Turks, a population with elevated hepatic lipase: high density lipoprotein characterization and gender-specific effects of apolipoprotein E genotype

Abstract

Turks have strikingly low levels of high density lipoprotein cholesterol (HDL-C) (10-15 mg/dL lower than those of Americans or Western Europeans) associated with elevated hepatic lipase mass and activity. Here we report that Turks have low levels of high density lipoprotein subclass 2 (HDL 2 ), apoA-I-containing lipoproteins (LpA-I), and pre-␤ -1 HDL and increased levels of HDL 3 and LpA-I/A-II particles (potentially an atherogenic lipid profile). The frequency distributions of HDL-C and LpA-I levels were skewed toward bimodality in Turkish women but were unimodal in Turkish men. The apoE genotype affected HDL-C and LpA-I levels in women only. In women, but not men, the 2 allele was strikingly more prevalent in those with the highest levels of HDL-C and LpA-I than in those with the lowest levels. The higher prevalence of the 2 allele in these subgroups of women was not explained by plasma triglyceride levels, total cholesterol levels, age, or body mass index. The modulating effects of apoE isoforms on lipolytic hydrolysis of HDL by hepatic lipase (apoE2 preventing efficient hydrolysis) or on lipoprotein receptor binding (apoE2 interacting poorly with the low density lipoprotein receptors) may account for differences in HDL-C levels in Turkish women (the 2 allele being associated with higher HDL levels). In Turkish men, who have substantially higher levels of hepatic lipase activity than women, the modulating effect of apoE may be overwhelmed. The gender-specific impact of the apoE genotype on HDL-C and LpA-I levels in association with elevated levels of hepatic lipase provides new insights into the metabolism of HDL.

Distribution of Risk Factors and Prophylactic Drug Usage in Turkish Patients with Angiographically Established Coronary Artery Disease

“…In many studies conducted so far, lower TC levels in individuals living in Turkey have been observed. In these studies HDL-C levels in the population living in Turkey were also found to be considerably lower [13][14][15][16]. In our study 55% of the cases had HDL-C values lower than 40 mg/dl (1.1 mmol/l).…”

“…This ratio has a significant implication for the general population of Turkey as well as for cases with CAD. In studies analysing lipid profiles of the Turkish population, decreased TCs and greatly decreased HDL-C levels were observed [13][14][15][16]. Thus in the Turkish population higher TC/HDL-C ratios can be found despite low TC levels.…”

High prevalence of low HDL cholesterol concentrations and mixed hyperlipidemia in a Mexican nationwide survey

“…Genetic similarities between Mexican and Turkish populations have been described in other disorders, such as Behcet's Syndrome [based on the high frequency of HLA-B5 found in both populations (28)]. Recently, increased hepatic lipase activity has been described as a possible cause of low HDL cholesterol in Turkish men (29). This abnormality remains to be studied in our population.…”

Plasma lipids in Turkish children: impact of puberty, socioeconomic status, and nutrition on plasma cholesterol and HDL

“…These low HDL-C levels appear to be largely of genetic origin because they are also observed in Turks living in Germany and the United States (4,5). Furthermore, in both Turkish men and women, the low HDL-C level is associated with 25-30% greater hepatic lipase activity than in white American controls (5) and is characterized by low levels of HDL 2 and LpA-I, consistent with elevated hepatic lipase levels (6). In addition, socioeconomic status (SES) has a major impact on fasting cholesterol levels, which are 30-40 mg/dl higher in Turkish men and women of high SES than in those of low SES.…”

“…Kits for the lipid and glucose assays were from Boehringer-Mannheim (Mannheim, Germany). A multichannel analyzer (Hitachi, Tokyo, Japan) was used for the colorometric enzymatic determinations of cholesterol (Monotest Cholesterol, CHOD-PAP), triglyceride (Peridochrom Triglyceride, GPO-PAP), and glucose (Glucose, GOD-PAP) (5,6). The Friedewald calculation was used to estimate LDL cholesterol (LDL-C) values (7).…”