Genetic and nongenetic determinants of blood pressure in a southern Brazilian sample

Genetic architecture of complex traits predisposing to nephropathy: hypertension

Blood pressure and hypertension have significant genetic underpinnings that may be age-dependent. The age-dependency, significant contributions from environmental factors such as diet and exercise, and inherent moment-to-moment variability complicate the identification of the genes contributing to the development of hypertension. Although genetic abnormalities may have moderate effects, the physiologic pathways involving these genes have redundant compensating mechanisms to bring the system back into equilibrium. This has the effect of reducing or completely masking the initial genetic defects, one of the hypothesized reasons for the small genetic effects found by the recent genome-wide association studies. This review article discusses the concept of initiators versus compensators in the context of finding genes related to hypertension development. A brief review is provided of some key genes found to be associated with hypertension, including the genes identified from the nine genome-wide association studies published to date.

Adult family members and their resemblance of coronary heart disease risk factors: the Cardiovascular Disease Study in Finnmark

Coronary heart disease tends to run in families, and the familial resemblance of major risk factors for the disease was examined among various types of adult family members. Family units were assembled from a total of 4,738 men and women who took part in a cross sectional health survey in four Norwegian municipalities where all inhabitants between 20 and 52 years of age were invited. After adjusting for age and other confounders, correlation coefficients were derived as a measure of the degree of resemblance. Viewed across all types of investigated familial relationships, similarity was found to be stronger for total cholesterol than for high-density lipoprotein cholesterol and triglycerides, and also stronger for systolic than for diastolic blood pressure. Between husbands and wives (3,060 subjects), correlations were small (between 0.02 and 0.06), except for 0.11 for total cholesterol. Lipid and blood pressure correlations ranged from 0.13 to 0.27 for parents and their offspring (471 subjects, p < 0.05) and from 0.11 to 0.22 among siblings (2,166 subjects, p < 0.01). Sibling correlations were consistent across age groups. Furthermore, reports from each individual on daily smoking (yes or no) revealed that husbands and wives had similar habits in 63.5% of all marriages as compared with the expected 49.4% had no smoking similarity at all been present. Smoking concordance was also demonstrated among siblings (p < 0.01). The persistent pattern of lipid and blood pressure aggregation among genetically related individuals from 20 to 52 years of age and the much weaker such similarity between husbands and wives, point towards genes or commonly shared environment at early ages as a major reason why coronary heart disease runs in families.

Biometrical genetic analysis of blood pressure level in the genetically hypertensive mouse

Hypertensive mice of the inbred strain BPH/2 were mated to mice of the inbred hypotensive BPL/1, and their hybrid offspring were crossed and intercrossed. The systolic blood pressures of the resulting ten populations were then subjected to a biometrical genetic analysis to determine the mode of inheritance of genes regulating blood pressure in these strains. It was found that the inheritance of elevated blood pressure was due, primarily, to the additive effects of three to five genes. There was no evidence that genetic dominance or epistasis were involved in the genetic control of blood pressure in these strains.

DNA polymorphisms of human apolipoprotein A-IV gene: frequency and effects on lipid, lipoprotein and apolipoprotein levels in a French population

Genetic polymorphisms of apolipoprotein (apo) A-IV have been shown to influence lipoprotein metabolism in some human populations. In this study, we have evaluated the physiological effect of three apo A-IV polymorphisms (Gln360- > His, Thr347- > Ser and XbaI within the second intron of the apo A-IV gene), in a French population, on seven quantitative traits: total cholesterol and triglycerides, cholesterol of HDL, apo A-IV, apo B, apo A-I and glucose. The polymorphism at amino-acid 360 was determined by direct analysis of polymerase chain reaction products. The allele frequencies were 0.92 for the A-IV1 and 0.08 for the A-IV2 allele. The genetic polymorphism at codon 347 was investigated by allele-specific oligonucleotide hybridization. The allele frequencies of the two alleles, A-IV347Thr and A-IV347Ser, were 0.78 and 0.22, respectively. The XbaI polymorphism was investigated by polymerase chain reaction followed by XbaI restriction enzyme digestion of the amplified products. The frequencies of the two apo A-IV alleles, XbaI-1 and XbaI-2, were 0.79 and 0.21, respectively. None of the three apo A-IV polymorphisms had a significant effect on lipoprotein, apolipoprotein and glucose levels.