Frequency and characterization of RHD and RHCE variants in the Noir Marron population from French Guiana.

BACKGROUND: The RH system is one of the most polymorphic blood group systems due to the proximity and opposite orientation of RHD and RHCE genes. Numerous alleles are described and can affect Rh protein expression. This complexity is especially evident in populations of African origin. We performed RHD and RHCE genotyping of the Noir Marron population in French Guiana. This population belongs to the Maroon community who are direct descendants of African slaves, who escaped from Dutch plantations, in the current day Suriname, during the 17th century. They represent an original ethnic group with highly blended culture. METHODS AND MATERIALS: A total of 89 DNA samples were collected from four different ethnic groups of the Noir Marron population of French Guiana. RHD and RHCE genotyping was performed using DNA microarray and/or sequencing. RESULTS AND DISCUSSION: Significant allelic diversity was shown, with 45% of individuals presenting an RHD gene variant (most common: RHD*DAU, RHD*DIVa, and RHD*DIIIa allele) and 9.4% with a partial D phenotype. Likewise, 85% presenting an RHCE gene variant and 9% a partial RH2 antigen. One original allele was identified in two D+ Noir Marron individuals: a hybrid RHD*DIIIa-CE(9)-D allele, encoding probably a partial D antigen and associated with an RHCE*ce(48C,733G,1006T) allele. The African diversity of RHD and RHCE genes is found in this population with preserved genetic but mixed cultural backgrounds. These data allow us to describe the characteristics of the RH system antigen and highlights a significant number of partial antigens with a risk of alloimmunization.

Sub-Saharan red cell antigen phenotypes and glucose-6-phosphate dehydrogenase deficiency variants in French Guiana.

BACKGROUND: The treatment of Plasmodium vivax infections requires the use of primaquine, which can lead to severe haemolysis in glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals. However, most of the Latin American countries, which are still endemic for vivax malaria, lack information on the distribution of G6PD deficiency (G6PDd). No survey has been performed so far in French Guiana. Herein, 80 individuals of the French Guianan Noir Marron population were scrutinized for red cell surface antigens of six blood group systems (ABO, Rh, Kell, Kidd, Duffy and MNS) and G6PD genetic polymorphisms. First, the sub-Saharan origin of the red cell phenotypes was assessed in relation with the literature. Then, given that the main sub-Saharan G6PDd variants are expected to be encountered, only the G6PD sequences of exons 4, 5, 6 and 9 were screened. This work aims at appraising the G6PD gene variation in this population, and thus, contributing to the G6PD piecemeal information in Latin America. RESULTS: Ninety-seven percent (97 %) of the red cells are Fy(a- b-), either D+ C- E- c+ e+ or D+ C+ E- c+ e+ and 44 % exhibited the Fya-/Jkb-/S- combined phenotype. Noteworthy is the detection of the G6PD(Val68Met) variant characterized by c.202G > A transition, G6PD(Asn126Asp) variant characterized by c.376A>G transition and G6PD(Asp181Val) variant characterized by c.542A>T transversion of the G6PD gene in 22.5 % of the sample, characteristic of the A(-(202)), A and Santamaria G6PDd variants, respectively. CONCLUSIONS: French Guianan Noir Marron population represents a pool of Rh-D antigen positive, Duffy-negative and G6PD-deficient erythrocytes, the latter accounting for one in every eight persons. The present study provides the first community-based estimation of the frequency of G6PDd polymorphisms in French Guiana. These results contribute to the G6PD genetic background information puzzle in Latin America.

The Hmong Diaspora: preserved South-East Asian genetic ancestry in French Guianese Asians.

The Hmong Diaspora is one of the widest modern human migrations. Mainly localised in South-East Asia, the United States of America, and metropolitan France, a small community has also settled the Amazonian forest of French Guiana. We have biologically analysed 62 individuals of this unique Guianese population through three complementary genetic markers: mitochondrial DNA (HVS-I/II and coding region SNPs), Y-chromosome (SNPs and STRs), and the Gm allotypic system. All genetic systems showed a high conservation of the Asian gene pool (Asian ancestry: mtDNA=100.0%; NRY=99.1%; Gm=96.6%), without a trace of founder effect. When compared across various Asian populations, the highest correlations were observed with Hmong-Mien groups still living in South-East Asia (Fst<0.05; P-value<0.05). Despite a long history punctuated by exodus, the French Guianese Hmong have maintained their original genetic diversity.

Evolutionary responses to a constructed niche: ancient Mesoamericans as a model of gene-culture coevolution.

Culture and genetics rely on two distinct but not isolated transmission systems. Cultural processes may change the human selective environment and thereby affect which individuals survive and reproduce. Here, we evaluated whether the modes of subsistence in Native American populations and the frequencies of the ABCA1*Arg230Cys polymorphism were correlated. Further, we examined whether the evolutionary consequences of the agriculturally constructed niche in Mesoamerica could be considered as a gene-culture coevolution model. For this purpose, we genotyped 229 individuals affiliated with 19 Native American populations and added data for 41 other Native American groups (n = 1905) to the analysis. In combination with the SNP cluster of a neutral region, this dataset was then used to unravel the scenario involved in 230Cys evolutionary history. The estimated age of 230Cys is compatible with its origin occurring in the American continent. The correlation of its frequencies with the archeological data on Zea pollen in Mesoamerica/Central America, the neutral coalescent simulations, and the F(ST)-based natural selection analysis suggest that maize domestication was the driving force in the increase in the frequencies of 230Cys in this region. These results may represent the first example of a gene-culture coevolution involving an autochthonous American allele.

Genetic variation among major human geographic groups supports a peculiar evolutionary trend in PAX9.

A total of 172 persons from nine South Amerindian, three African and one Eskimo populations were studied in relation to the Paired box gene 9 (PAX9) exon 3 (138 base pairs) as well as its 5'and 3'flanking intronic segments (232 bp and 220 bp, respectively) and integrated with the information available for the same genetic region from individuals of different geographical origins. Nine mutations were scored in exon 3 and six in its flanking regions; four of them are new South American tribe-specific singletons. Exon3 nucleotide diversity is several orders of magnitude higher than its intronic regions. Additionally, a set of variants in the PAX9 and 101 other genes related with dentition can define at least some dental morphological differences between Sub-Saharan Africans and non-Africans, probably associated with adaptations after the modern human exodus from Africa. Exon 3 of PAX9 could be a good molecular example of how evolvability works.

French Guiana Amerindian demographic history as revealed by autosomal and Y-chromosome STRs.

BACKGROUND: Previous investigations of French Guiana Amerindians performed by this group included blood group and protein genetic markers, mitochondrial DNA and Y-chromosome investigations. Molecular autosomal data and more extensive Y-chromosome determinations were lacking. SUBJECTS AND METHODS: The genetic variability of 15 autosome (ASTRs) and 17 Y-chromosome (YSTRs) microsatellite loci was studied in four French Guiana (Emerillon, Palikur, Wayampi, Kali'na) and one Brazilian (Apalai) Amerindian populations. A sixth group, the Peruvian Matsiguenga of the Maipurean linguistic family, was included in the data analysis since they could provide information about the past migration of people from that linguistic stock into northeastern Amazonia. RESULTS: Marked ASTR and YSTR variability was found, with 96% of the YSTR haplotypes being found in one population only. There was excellent agreement between the present and previous autosomal or uniparental results. Multidimensional scaling based on F(ST) genetic distances and population structure analysis revealed heterogeneity in gene distribution, with a clear difference between the Matsiguenga and Emerillon and the other groups. In the latter, Wilcoxon sign-rank test between observed and expected heterozygosity and the mode of allele frequency distribution revealed clues of a significant past genetic bottleneck. The Wayampi stand genetically closer to the Apalai, Palikur and Kali'na when examined for the autosome but not the Y-chromosome panel of markers, suggesting preferential female gene flow. CONCLUSION: The new data provided additional important information about the biological history of people from a remote South American region, indicating how gene diversity analyses can be used to increase understanding of human microevolutionary processes.

Population genetic dynamics in the French Guiana region.

Three sets of genetic markers (blood group plus protein polymorphisms, mitochondrial DNA, and Y-chromosome) were compared in four French Guiana and one Brazilian Amerindian populations. Spearman's rank correlation coefficient between five gene diversity statistics and historical or present-day population sizes showed significant values, indicating loss of diversity due to population bottlenecks. The three sets of markers furnished distinct admixture estimates, and the blood group plus protein polymorphisms could have overestimated the European contribution to their gene pool. Correspondence analysis distinguished the coastal from the interior populations, possibly reflecting past migration events.

Genetic studies in French Guiana populations: Synthesis.

Twelve blood group and protein systems from a total of 819 individuals from six tribal groups (Apalaí-Wayana, Emerillon, Kaliña, Palikur Wayampi, and Wayana) living in French Guiana and Brazil were compared with each other and integrated with previous results from 17 other South Amerindian populations studied for the same genetic markers. Using correspondence analysis, map methodologies, and maximum linkage cluster analysis developed with the UPGMA method, we attempted to establish the genetic position of these tribes among South American Indians. Peripheral positions for the Emerillon and the Palikur were observed. Ethnohistorical data in French Guiana suggest that a strong founder effect for the former and endogamy for the latter could have generated the genetic differentiation of these two ethnic groups. However, when considered in a wider context, all French Guiana Natives cluster together in an intermediate position as compared with 17 other Amerindian groups studied for the comparison.