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West African Populations (west + african_population)
Selected AbstractsGenetic Diversity of the Fragile X Syndrome Gene (FMR1) in a Large Sub-Saharan West African PopulationANNALS OF HUMAN GENETICS, Issue 4 2010Emmanuel K. Peprah Summary Fragile X syndrome (OMIM #300624) is caused by the expansion of a CGG trinucleotide repeat found in the 5, untranslated region of the X-linked FMR1 gene. Although examinations of characteristics associated with repeat instability and expansion of the CGG repeat upon transmission from parent to offspring has occurred in various world populations, none has been conducted in large Sub-Saharan African populations. We have examined the FMR1 CGG repeat structure in a sample of 350 males drawn from the general population of Ghana. We found that Ghanaians and African Americans have similar allele frequency distributions of CGG repeat and its flanking STR markers, DXS548 and FRAXAC1. However, the distribution of the more complex marker, FRAXAC2, is significantly different. The haplotype structure of the FMR1 locus indicated that Ghanaians share several haplotypes with African Americans and Caucasians that are associated with the expanded full mutation. In Ghanaians, the majority of repeat structures contained two AGG interruptions, however, the majority of intermediate alleles (35,49) lacked AGG interruptions. Overall, we demonstrate that allelic diversity of the FMR1 locus among Ghanaians is comparable to African Americans, but includes a minority of CGG array structures not found in other populations. [source] Molecular epidemiology of hepatitis B virus in Dakar, SénégalJOURNAL OF MEDICAL VIROLOGY, Issue 3 2006Muriel Vray Abstract Using DNA chip technology and real-time quantitative PCR, molecular profile of HBV strains infecting blood donors and patients in Dakar, Sénégal was studied. All HBsAg-positive blood donors (n,=,175) and all patients who presented with chronic hepatitis B (n,=,29) between 1st June 2003 and 31st July 2003 were studied. One patient, a blood donor, was coinfected by HCV, and nine patients had anti-HDV antibodies. Few persons in either group were HBeAg-positive. Viral load values were relatively low but correlated with biochemical abnormalities. Patients were infected mainly by genotype E (72%). Patients infected by genotype A (28%) tended to be younger than other patients. There was no significant difference between the blood donors and the patients with hepatitis B as regards virological markers, including viral load, when the HBV genotype was taken into account. The BCP A1762T and G1764A mutations were found in four patients and one patient, respectively; the two mutations were never found in the same patient. The W28* mutation at position 1896 of the core was detected in 19 of the 32 genotyped patients, 18 (83%) of whom had genotype E infection. ALT levels were not influenced by HBV mutations. This study shows a low frequency of clinical signs in HBsAg-positive blood donors, a relatively low level of viral replication, and a high frequency of pre-core mutants in this West African population. These results underline the importance of molecular characterization of HBV infection as specific treatments become available in this region. J. Med. Virol. 78:329,334, 2006. © 2006 Wiley-Liss, Inc. [source] Association of ankylosing spondylitis with HLA,B*1403 in a West African populationARTHRITIS & RHEUMATISM, Issue 11 2002Carlos López-Larrea Objective To investigate the contribution of HLA class I alleles in the susceptibility to primary ankylosing spondylitis (AS) in West African patients living in Togo. Methods A large epidemiologic analysis of 9,065 West African rheumatology patients living in Togo was performed in order to identify those who had AS. Eight Togolese patients with AS were identified. HLA was typed by polymerase chain reaction using sequence-specific oligonucleotide probes. DNA typing was also performed on a control population of 85 healthy subjects matched for ethnic background. Results A significant association between AS and B*14 was identified. This allele was found in 62.5% of the AS patients (odds ratio 69), but was carried by only 2% of the healthy controls. Analysis for B14 subtypes showed that B*1403 was the predominant allele in AS patients (odds ratio 171), and that this allele was absent in healthy controls. B27 was virtually absent, being observed in only 1 AS patient (B*2705). Conclusion HLA,B*1403 shows the B27 "supertype" motif and may exert an effect on AS susceptibility according to the arthritogenic peptide model. The association of B*1403 with AS has not previously been reported in either population. [source] Extreme long-distance dispersal of the lowland tropical rainforest tree Ceiba pentandra L. (Malvaceae) in Africa and the NeotropicsMOLECULAR ECOLOGY, Issue 14 2007CHRISTOPHER W. DICK Abstract Many tropical tree species occupy continental expanses of rainforest and flank dispersal barriers such as oceans and mountains. The role of long-distance dispersal in establishing the range of such species is poorly understood. In this study, we test vicariance hypotheses for range disjunctions in the rainforest tree Ceiba pentandra, which is naturally widespread across equatorial Africa and the Neotropics. Approximate molecular clocks were applied to nuclear ribosomal [ITS (internal transcribed spacer)] and chloroplast (psbB- psbF) spacer DNA sampled from 12 Neotropical and five West African populations. The ITS (N = 5) and psbB- psbF (N = 2) haplotypes exhibited few nucleotide differences, and ITS and psbB- psbF haplotypes were shared by populations on both continents. The low levels of nucleotide divergence falsify vicariance explanations for transatlantic and cross-Andean range disjunctions. The study shows how extreme long-distance dispersal, via wind or marine currents, creates taxonomic similarities in the plant communities of Africa and the Neotropics. [source] Prevalence and time trends in obesity among adult West African populations: a meta-analysisOBESITY REVIEWS, Issue 4 2008A. R. Abubakari Summary The objective of this study was to determine the distribution of and trends in obesity in adult West African populations. Between February and March 2007, a comprehensive literature search was conducted using four electronic databases. Journal hand searches, citations and bibliographic snowballing of relevant articles were also undertaken. To be included, studies had to be population-based, use well-defined criteria for measuring obesity, present data that allowed calculation of the prevalence of obesity and sample adult participants. Studies retrieved were critically appraised. Meta-analysis was performed using the DerSimonian-Laird random effect model. Twenty-eight studies were included. Thirteen studies were conducted in urban settings, 13 in mixed urban/rural and one in rural setting. Mean body mass index ranged from 20.1 to 27.0 kg2. Prevalence of obesity in West Africa was estimated at 10.0% (95% CI, 6.0,15.0). Women were more likely to be obese than men, odds ratios 3.16 (95% CI, 2.51,3.98) and 4.79 (95% CI, 3.30,6.95) in urban and rural areas respectively. Urban residents were more likely to be obese than rural residents, odds ratio 2.70 (95% CI, 1.76,4.15). Time trend analyses indicated that prevalence of obesity in urban West Africa more than doubled (114%) over 15 years, accounted for almost entirely in women. Urban residents and women have particularly high risk of overweight/obesity and obesity is rising fast in women. Policymakers, politicians and health promotion experts must urgently help communities control the spread of obesity in West Africa. [source] Analysis of mitochondrial DNA diversity in Burkina Faso populations confirms the maternal genetic homogeneity of the West African goatANIMAL GENETICS, Issue 3 2009L. J. Royo Summary To date, no comprehensive study has been performed on mitochondrial genetic diversity of the West African goat. Here, we analysed a 481-bp fragment of the HVI region of 111 goats representing four native West African populations, namely the three main Burkina Faso breeds, zoo-farm kept Dwarf goats and endangered Spanish goat breeds used as the outgroup. Analyses gave 83 different haplotypes with 102 variable sites. Most haplotypes (65) were unique. Only three haplotypes were shared between populations. Haplotypes were assigned to cluster A except for H45 (belonging to the Spanish Bermeya goat) which was assigned to cluster C. amova analysis showed that divergence between groups (,CT) was not statistically significant regardless of whether the partition in two hierarchical levels that was fitted included Spanish samples or not. The West African goat scenario shown here is consistent with that previously reported for the species: haplogroup A is predominant and has a very high haplotype diversity regardless of the geographic area or sampled breed. The large phenotypic differences observable between the West African Dwarf and Sahelian long-legged goat populations are not detectable with mitochondrial markers. Moreover, a previously suggested introgression of Sahelian goat southwards because of desertification could not be assessed using mtDNA information. [source] | |||||||||||||