Calpain-10 gene polymorphisms and type 2 diabetes in West Africans: the Africa America Diabetes Mellitus (AADM) Study.

PURPOSE: To investigate whether the three single nucleotide polymorphisms (SNPs), SNP-43, -56, and -63 of CAPN10 were associated with type 2 diabetes in a West African cohort. METHODS: A total of 347 diabetic subjects and 148 unaffected controls from four ethnic groups in two West African countries were enrolled in this study. After genotyping three SNPs of CAPN10 and one SNP from CYP19, the allele, genotype, and haplotype frequencies as well as the odds ratios were calculated to test their association with type 2 diabetes. RESULTS: None of the alleles or genotypes was associated with type 2 diabetes. Although statistical analysis indicated that haplotype 221 was associated with type 2 diabetes (OR, 3.765; 95% CI, 1.577-8.989) in the two ethnic groups of Nigeria, the same haplotype did not show any association with type 2 diabetes in the two ethnic groups in Ghana (OR, 0.906; 95% CI, 0.322-2.552). CONCLUSION: Considering the relatively low frequency of haplotype 221 and that none of the haplotypes including 221 was associated with any of the diabetes-related quantitative traits tested, it is concluded that SNP-43, -56, and -63 of the CAPN10 gene variants may play a limited role in the risk of type 2 diabetes risks in this cohort of West Africans.

Genetic epidemiology of hypertension: an update on the African diaspora.

Hypertension is a serious global public health problem, affecting approximately 600 million people worldwide. The lifetime risk of developing the condition exceeds 50% in most populations. Despite considerable success in the pharmacological treatment of hypertension in all-human populations, the health-care community still lacks understanding of how and why individuals develop chronically elevated blood pressure. This gap in knowledge, and the high prevalence of hypertension and associated complications in some populations of African descent, have led some to conclude that hypertension is a "different disease" in people of African descent. Despite considerable evidence from epidemiologic studies showing that blood pressure distribution in populations of the African diaspora spans the known spectrum for all human populations, theories in support of unique "defects" among populations of African descent continue to gain wide acceptance. To date, no known environmental factors or genetic variants relevant to the pathophysiology of human hypertension have been found to be unique to Black populations. However, available genetic epidemiologic data demonstrate differential distributions of risk factors that are consistent with current environmental and geographic origins. This review summarizes the available evidence and demonstrates that as the exposure to known risk factors for hypertension (eg, excess consumption of salt and calories, stress, sedentary lifestyle, and degree of urbanization) increases among genetically susceptible individuals, the prevalence of hypertension and associated complications also increases across populations of the African diaspora. This observation is true for all human populations.

The atrial natriuretic peptide gene and essential hypertension in African-Caribbeans from St. Vincent and the Grenadines

Atrial natriuretic peptide (ANP) which alters sodium balance, blood volume and vascular tone represents an important candidate for investigating the genetic basis of essential hypertension (EH). Accordingly, we have studied Bg11 and Xho1 restriction fragment length polymorphisms (RFLPs) of the ANP gene in 147 hypertensive, 141 normotensive and 67 population-based control subjects from a homogenous population of West African origin from St Vincent and the Grenadines. We found no association of either Bg11 and Xho1 RFLPs with EH. This study suggests that the ANP locus may not exert a major gene effect on EH amongst the black people of St. Vincent and the Grenadines.(AU)

Linkage of the angiotensin gene locus to human essential hypertension in African Caribbeans

The renin-angiotensin system regulates blood pressure and sodium balance. The angiotensinogen gene which encodes the key substrate within the system has been linked to essential hypertension in white Europeans. It has been suggested that people of West African ancestry may have a different genetic basis for hypertension. In this study we have tested whether there is linkage of the angiotensinogen to essential hypertension in African Caribbeans from St. Vincent and the Grenadines. DNA from 63 affected sibling pairs with hypertension was tested for linkage by analyzing whether there was excess allele sharing among sibling genotyped using an angiotensingogen dinucleotide repeat sequence. There was significant support for linkage (T = 3.07, P = 0.001) and association of this locus to hypertension (Xý = 50.2, 12 degrees of freedom, P ó 0.001). A DNA polymorphism which alters methionine to threonine at position 235 (M235T) within the angiotensinogen peptide has been associated previously with hypertension. However, we found no association of this variant with hypertension in this study. These findings provide support for linkage and association of the angiotensinogen locus to hypertension in African Caribbeans and suggest some similarities in the genetic basis of essential hypertension in populations of different ethnicity (AU)

Investigation of the renin gene as a putative locus for essential hypertension (EH) in Vincentian African Caribbeans

Epidemiological studies have consistently reported a higher prevalence of essential hypertension in black people. Other data indicate that black people may have salt regulatory systems with low reserves which are unable to cope with moderate quantities of salt and respond to salt loading by increasing their blood pressures. Black people are therefore susceptible to the deleterious effects of salt. As some forms of EH may be related to defects in salt regulatory systems, we investigated association of the renin gene locus (the rate limiting enzyme in an important salt regulatory system) with EH in an ethnically homogenous group of black people of African origin (Summary)