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

Turks have strikingly low levels of high density lipoprotein cholesterol (H DLC) (10-15 mg/dL lower than those of Americans or Western Europeans) assoc iated with elevated hepatic lipase mass and activity, Here we report that T urks have low levels of high density lipoprotein subclass 2 (HDL2), apoA-co ntaining lipoproteins (LpA-I), and pre-P-l HDL and increased levels of HDL3 and LpA-I/A-II particles (potentially an atherogenic lipid profile). The f requency distributions of HDLC and LpA-I levels were skewed toward bimodali ty in Turkish women but were unimodal in Turkish men, The apoE genotype aff ected HDL-C and LpA-I levels in women only In women, but not men, the epsil on 2 allele was strikingly more prevalent in those with the highest levels of HDLC and LpA-I than in those with the lowest levels. The higher prevalen ce of the epsilon 2 allele in these subgroups of women was not explained by plasma triglyceride levels, total cholesterol levels, age, or body mass in dex, The modulating effects of apoE isoforms on lipolytic hydrolysis of HDL by hepatic lipase (apoE2 preventing efficient hydrolysis) or on lipoprotei n receptor binding (apoE2 interacting poorly with the low density lipoprote in receptors) may account for differences in HDLC levels in Turkish women ( the epsilon 2 allele being associated with higher HDL levels), In Turkish m en, who have substantially higher levels of hepatic lipase activity than wo men, the modulating effect of apoE may be overwhelmed.jlr The gender-specif ic impact of the apoE genotype on HDLC and LpA-I levels in association with elevated levels of hepatic lipase provides new insights into the metabolis m of HDL.