Imbalanced distribution of GM immunoglobulin allotypes according to the clinical presentation of Plasmodium falciparum malaria in beninese children

Selection pressure exerted by pathogens contributes to the persistence of polymorphisms in GM and KM allotypes, which are antigenic determinants of immunoglobulins. This study investigated the impact of GM and KM allotypes on the clinical response to Plasmodium falciparum infection among Beninese children, including 65 with severe malaria, 37 with uncomplicated malaria, and 53 with asymptomatic carriage. An inverse relationship was found between the GM5,6,13,14; 1,17 phenotype and uncomplicated malaria. Genetic markers implicated in the composition and activity of immunoglobulins may be associated with the genetic control of both malaria infection and morbidity

HLA-Gm/kappam interaction in sarcoidosis. Suggestions for a complex genetic structure

The aetiology of sarcoidosis is still unknown. Environmental exposures are believed to interact with genetic factors in determining the pattern of sarcoidosis presentation, progression and prognosis. The frequency of serological polymorphism of immunoglobulin G heavy chain (Gm) and kappa light chain (kappam) markers in 107 patients with biopsy-proven sarcoidosis and in 227 controls, and their interactions with histocompatibility leukocyte antigen (HLA) class I, II, and III markers, were studied. A "protective" effect of the Gm(3 5*) phenotype in the sarcoid group versus controls (p-value for number of specificities tested (p(c))=0.05, odds ratio 0.15) and a reduced frequency of Gm(3 23 5*) in patients with advanced chest radiographic stage (Chi-squared (two degrees of freedom)(chi2(2df) 17.61, p(c)=0.0058) were observed. With reference to epistatic interactions, the combination Gm(3 23 5*)/BfS had a "protective" effect towards stage II (chi2(2dt) 13.86, p(c)=0.043). Finally, correspondence analysis defined two clusters: HLA-DR4, C4BQ0, Gm(1, 3, 17 23 5*, 21, 28) and BfF associated with stage II, and HLA-DR3, C4AQ0, kappam(1) and Gm(3 23 5*) associated with stage I. These data further support the hypothesis that sarcoidosis results from an interplay of environmental factors and genes, each contributing to the susceptibility/resistance to and/or the clinical heterogeneity of the disease. In addition, these data provide the first evidence of an interaction between immunoglobulin G heavy chain/kappa light chain markers and histocompatibility leukocyte antigen class III genes in a disease

An unexpected wide population variation of the G1733A polymorphism of the androgen receptor gene: Data on the Mediterranean Region

The androgen receptor (AR) has been proposed as a candidate gene for several cancers (breast, prostate, uterine endometrium, colon, and esophagus). Ethnicity is considered an associated risk factor for some of these cancers. Several case-control genetic studies have been focused in samples of the main ethnic groups, but little is known about the distribution of risk polymorphisms in current populations with accurate ethnic and/or geographic origins. The A allele of the G1733A polymorphism of the AR gene has been associated with increased risk of prostate cancer. We provide data from this marker in 12 samples from 7 Mediterranean countries such as Spain, Italy (Sardinia), Greece, Turkey, Morocco, Algeria, and Egypt. A sample from Ivory Coast has also been analyzed. The A allele distribution shows a frequency in the Ivory Coast population (65.17%) that contrasts with the low values found in Northern Mediterraneans (mean average value of 13.98%). North African populations present two-times higher frequencies (average value of 27.19%) than Europeans. The wide population variation range found for the A allele strengthens the potential interest of further screening as a baseline to the design of future preventive and population health programs. © 2005 Wiley-Liss, Inc

Response to Timing of a Back-Migration into Africa

The principal problem with great syntheses of languages, genes, and figurines (or pots) is that they lump together different migrational and cultural processes and especially overstretch recent events of the Holocene, thereby downplaying or swamping the genetic signals that point to much earlier events of the Pleistocene (1, 2). Forster and Romano propose a recent arrival—within the last 2000 to 15,000 years—of haplogroup M1 in North Africa from western Asia, linked to the spread of Afro-Asiatic languages. This would entail a Near Eastern origin of the Afro-Asiatic language family and thus would be in agreement with Bellwood (3), provided that one subscribes to such a tight link between genes and languages. Afro-Asiatic scholarship (4), as well as the coalescence times of both M1a and M1b and the diverse basal distribution of M1a lineages especially in East Africa, however, militate against this interpretation. As we proposed in our Report, the arrival of M1 in Africa is most likely contemporary with that of U6, but if one alternatively hypothesized that only M1a originally went into the Northeast African Mediterranean coast, then 25,000 to 30,000 years ago would be the realistic time frame

Genome-wide ancestry and demographic history of African-descendant Maroon communities from French Guiana and Suriname

The transatlantic slave trade was the largest forced migration in world history. However, the origins of the enslaved Africans and their admixture dynamics remain unclear. To investigate the demographic history of African-descendant Marron populations, we generated genome-wide data (4.3 million markers) from 107 individuals from three African-descendant populations in South America, as well as 124 individuals from six west African populations. Throughout the Americas, thousands of enslaved Africans managed to escape captivity and establish lasting communities, such as the Noir Marron. We find that this population has the highest proportion of African ancestry (∼98%) of any African-descendant population analyzed to date, presumably because of centuries of genetic isolation. By contrast, African-descendant populations in Brazil and Colombia harbor substantially more European and Native American ancestry as a result of their complex admixture histories. Using ancestry tract-length analysis, we detect different dates for the European admixture events in the African-Colombian (1749 CE; confidence interval [CI]: 1737-1764) and African-Brazilian (1796 CE; CI: 1789-1804) populations in our dataset, consistent with the historically attested earlier influx of Africans into Colombia. Furthermore, we find evidence for sex-specific admixture patterns, resulting from predominantly European paternal gene flow. Finally, we detect strong genetic links between the African-descendant populations and specific source populations in Africa on the basis of haplotype sharing patterns. Although the Noir Marron and African-Colombians show stronger affinities with African populations from the Bight of Benin and the Gold Coast, the African-Brazilian population from Rio de Janeiro has greater genetic affinity with Bantu-speaking populations from the Bight of Biafra and west central Africa

Tracing past human male movements in northern/eastern Africa and western Eurasia: new clues from Y-chromosomal haplogroups E-M78 and J-M12.

Detailed population data were obtained on the distribution of novel biallelic markers that finely dissect the human Y-chromosome haplogroup E-M78. Among 6,501 Y chromosomes sampled in 81 human populations worldwide, we found 517 E-M78 chromosomes and assigned them to 10 subhaplogroups. Eleven microsatellite loci were used to further evaluate subhaplogroup internal diversification. The geographic and quantitative analyses of haplogroup and microsatellite diversity is strongly suggestive of a northeastern African origin of E-M78, with a corridor for bidirectional migrations between northeastern and eastern Africa (at least 2 episodes between 23.9-17.3 ky and 18.0-5.9 ky ago), trans-Mediterranean migrations directly from northern Africa to Europe (mainly in the last 13.0 ky), and flow from northeastern Africa to western Asia between 20.0 and 6.8 ky ago. A single clade within E-M78 (E-V13) highlights a range expansion in the Bronze Age of southeastern Europe, which is also detected by haplogroup J-M12. Phylogeography pattern of molecular radiation and coalescence estimates for both haplogroups are similar and reveal that the genetic landscape of this region is, to a large extent, the consequence of a recent population growth in situ rather than the result of a mere flow of western Asian migrants in the early Neolithic. Our results not only provide a refinement of previous evolutionary hypotheses but also well-defined time frames for past human movements both in northern/eastern Africa and western Eurasia