E65 K polymorphism in KCNMB1 gene is not associated with ischaemic heart disease in Spanish patients.

Hypertension is a main risk factor for atherosclerosis through vascular wall hyperplasia. A recent study reported a new polymorphism (E65 K) in the beta(1) subunit (KCNMB1) gene of the Ca(2+)-dependent potassium channel with a protective effect against the severity of diastolic hypertension, but further data have lead to conflicting results. In order to ascertain the involvement of the E65 K variant in cardiovascular system regulation, the potential association between this mutation and ischaemic heart disease was assessed through a family-based association study (n=302 individuals). Transmission disequilibrium analysis failed to detect any association between this polymorphism and ischaemic heart disease. Although a minor effect cannot be discarded, sample analytical power and negative results do not support a major role for E65 K polymorphism in atherogenic pathologies.

Population variability in some genes involving the haemostatic system: data on the general population of Corsica (France), Sardinia and Sicily (Italy)

Three different population samples from Corsica (France), Sardinia and Sicily (Italy) were studied using nine genetic markers. For the first time, allele distributions of FGA TaqI, FGB Bcl I, FGB Hind III, PAI-1 Hind III, PLAT TPA-25, GPIIIa Taq I, GPIIb I/D 9bp, FVII HVR4 and FVII -323 10 bp markers, which are thought to be associated with cardiovascular disease risk, were studied in the general population of the three islands. The frequencies of the markers analysed in the present work show some peculiarities: the locus FVII HVR4 is characterized by the presence of a rare allele (H5), found in Corsicans and in Sardinians; the locus FBG BcII shows a low frequency of the B1 allele and the absence of the B1B1 genotype. The frequencies of some alleles have a distribution that is in agreement with the low risk for cardiovascular diseases in south European countries. The results highlight a genetic differentiation between the three Mediterranean islands and the other European populations.

Molecular variation in endothelial nitric oxide synthase gene (eNOS) in western Mediterranean populations.

Endothelial nitric oxide synthase (eNOS or NOS3) is the main responsible for nitric oxide (NO) production in vascular system and different polymorphisms have been identified in epidemiological studies. Trying to test the eNOS genetic variation in general populations we studied the 27-bp VNTR in intron 4 and G894T substitution in exon 7 markers in 6 Western Mediterranean populations (3 from Iberian Peninsula, 1 from North Africa, and 2 from Sardinia) and a sample from Ivory Coast. The VNTR frequencies in Western Mediterranean and Ivory Coast fit well into the ranges previously described for Europeans and Sub-Saharans respectively, and a typical African allele has been detected in polymorphic frequencies in the Berber sample. The G894T substitution presents the highest frequencies described for the T allele in the North Mediterranean populations. Linkage disequilibrium is present between both markers in all populations except in the Ivory Coast sample. The variation found for these polymorphisms indicates that they may be a useful tool for population studies even at microgeographical level.

Molecular variation at functional genes and the history of human populations--data on candidate genes for cardiovascular risk in the Mediterranean.

A screening of 22 DNA polymorphisms has been performed in western Mediterranean populations (Iberian Peninsula, Morocco, and Central Mediterranean Islands). The analyzed markers correspond to polymorphic sites in several candidate genes for cardiovascular disease including apolipopoteins and their receptors (APOA1, APOB, APOE, APOC1, APOC2, LPA, and LDLR), genes implied in the hemostasis regulation (Factor VII, alpha and beta-fibrinogen, alpha and beta platelet-integrin, tissue plasminogen activator, and plasminogen activator inhibitor-1), and the angiotensin converting enzyme gene. The results are presented of a partial analysis carried out in following population samples: 6 from the Iberian Peninsula, 2 from Morocco, and 3 from Central Islands. The degree of inter-population diversity was significant and consistent with data from other kind of genetic polymorphisms. The apportionment of the allele frequency variance supported a geographic structure into three main regions: Central Mediterranean Islands, the Iberia Peninsula and North Africa. The genetic distance pattern is compatible with a south-to-north North African influence in the Iberian Peninsula and a remarkable gene flow from sub-Saharan Africa into Morocco. Epidemiologically, North Africa is characterized by high frequencies of LPA PNR alleles with high number of repeats (protective for cardiovascular risk) and high frequencies of the APOE*E4 allele (risk factor) as compared with European populations.

Lack of association between eNOS gene polymorphisms and ischemic heart disease in the Spanish population.

Through the nitric oxide (NO) production in the vascular system, the endothelial nitric oxide synthase (eNOS or NOS3) is a key enzyme in blood pressure regulation and atherosclerosis control. Several previous studies have suggested an important role of eNOS as a genetic risk factor for cardiovascular diseases. In this context, a genetic association study was carried out between two eNOS polymorphisms (the ecNOS4a/b VNTR and the G894T substitution) in a sample of 101 nuclear families having one affected offspring of ischemic heart disease (IHD). Transmission disequilibrium test (TDT) revealed partial associations between the VNTR marker and IHD in patients with a type A behavior pattern (TABP) (P = 0.0325, RR = 3.67) and for the haplotype formed by variant b of the VNTR and the T mutation of the G894T substitution in the IHD-affected subgroup having body mass index (BMI) lower than 25 (P = 0.0348, RR = 0.22). However, once multiple testing correction was applied, the associations became nonsignificant. A significant effect of the haplotype b-G increasing high-density lipoprotein cholesterol (HDL-C) plasma levels was detected (P = 0.021 after Bonferroni correction). From a population point of view, frequencies found for G894T substitution in Spain were significantly different from other populations.