Apolipoprotein E gene polymorphism and gender.

Many studies have shown that the prevalence and onset of coronary heart disease (CHD) is sex-dependent. CHD prevalence is lower in women than in men at all ages. Furthermore, women's age of CHD onset seems to be 10 yr later. This is widely attributed to the fact that men have less favorable CHD risk factors (eg, plasma lipid profile) compared to women. Mean levels of protective high density lipoprotein cholesterol are lower, while triglyceride levels are higher in men than in women. It is possible that many of the genes involved in lipid metabolism, such as Apolipoprotein (Apo) E, as well as their polymorphisms, may be expressed in a sexually dimorphic manner. The human Apo E gene is polymorphic, encoding one of 3 common epsilon (epsilon) alleles (epsilon 2, epsilon 3, epsilon 4), with the epsilon 3 allele occurring most frequently (78%) in the Caucasian population. Association studies have shown a protective effect on CHD in epsilon 2 carriers and a harmful effect in epsilon 4 carriers. However, there are conflicting results regarding such allelic effects in respect to gender. This review is focused on the gender-related influence of Apo E polymorphism in respect to plasma lipid levels and the risk of CHD. Additionally, an effort is made to determine if this relation exists and if it can be satisfactorily explained. The studies cited here demonstrate a complex, multifactorial association between these factors, in need of further corroboration in greater population samples.