The influence of ApoE genotype on the lipid profile and lipoproteins  during normal pregnancy in a Southern African population.

Donald Moshen Tanyanyiwa, Adrian David Marais, Pamela Byrnes, Sheena Jones
1. Division of Human Genetics, Department of Pathology and Institute of Infectious Disease and Molecular
Medicine, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town,
South Africa.
2. Division of Chemical Pathology, Department of Pathology, University of Witwatersrand/ National Health
Laboratory Services, Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa.
3. Department of Internal Medicine, University of Cape Town, Cape Town, South Africa.

Abstract
Background:Pregnancy is associated with increases in fasting triglycerides and total cholesterol.ApoE isoforms are known to  influence the concentration of cholesterol, with apoE2 homozygosity lowering and apoE4 homozygosity raising the cholesterol  concentration compared with E3 homozygosity.The lipid profiles ApoE status and prevalence of small dense LDL species were evaluated for subjects attending an antenatal clinic.

Results: Samples from 690 women aged between 16 and 42 years of age were analyzed during and after pregnancy. The fasting plasma triglyceride concentration (in mmol/L) was significantly higher in pregnancy (median = 1.5, IQR 1.0-2.0 vs median = 0.6,  IQR 0.5-0.8 respectively, p < 0.0001). Similarly, the total cholesterol (in mmol/L) was increased during pregnancy (median=4.1,  IQR 3.6-4.7 vs median 3.5, IQR 3.1-3.5, respectively p=0.0167). The median LDL cholesterol and HDL cholesterol did not  change. Higher proportions of small density LDL species were seen during pregnancy compared to after pregnancy. The distribution of the LDL species during pregnancy and 6 weeks post-partum were significantly different p<0.0001 with the smaller  species being much higher during pregnancy.

Conclusion:ApoE4 genotype was associated with increased total cholesterol and LDL cholesterol concentrations during pregnancy. Pregnancy results in a reversible remodeling of LDL to smaller species, the significance of which is unknown but may  indicate a predisposition to atherosclerosis

Keywords: Apolipoprotein E. Lipids, pregnancy, small dense LDL species, African.