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. 2017 Apr;25(4):472-476.
doi: 10.1038/ejhg.2016.200. Epub 2017 Jan 18.

A survey of sub-Saharan gene flow into the Mediterranean at risk loci for coronary artery disease

Miguel M Álvarez-Álvarez  1 , Daniela Zanetti  1 , Robert Carreras-Torres  1 , Pedro Moral  1 , Georgios Athanasiadis  2
Affiliations

A survey of sub-Saharan gene flow into the Mediterranean at risk loci for coronary artery disease

Miguel M Álvarez-Álvarez et al. Eur J Hum Genet. 2017 Apr.

Abstract

This study tries to find detectable signals of gene flow of Sub-Saharan origin into the Mediterranean in four genomic regions previously associated with coronary artery disease. A total of 366 single-nucleotide polymorphisms were genotyped in 772 individuals from 10 Mediterranean countries. Population structure analyses were performed, in which a noticeable Sub-Saharan component was found in the studied samples. The overall percentage of this Sub-Saharan component presents differences between the two Mediterranean coasts. D-statistics suggest possible Sub-Saharan introgression into one of the studied genomic regions (10q11). We also found differences in linkage disequilibrium patterns between the two Mediterranean coasts, possibly attributable to differential Sub-Saharan admixture. Our results confirm the potentially important role of human demographic history when performing epidemiological studies.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Populations studied. 1, Chouala; 2, Khenifra; 3, Las Alpujarras; 4, Valencia; 5, Basque Country; 6, Girona; 7, Toulouse; 8, M'zab; 9, Tunisia; 10, Sardinia; 11, Sicily; 12, Libya; 13, Bosnia-Herzegovina; 14, Crete; 15, Turkey; 16, General Jordan; 17, Bedouin.
Figure 2
Figure 2
(a) Topology assumed for the D-statistics, where X represents a Mediterranean population. (b) Boxplots showing the results of the D-statistics. The points represent the Z-score values (abscissas axis) obtained for each genomic region in a given Mediterranean population X (ordinates axis). As the topology assumed is (((X, CHB), YRI), Ancestral), significant Z-score-positive values indicate a gene flow event between YRI and X. The significance threshold is set at ±2. See legend at Figure 3 for clarification of the population names.
Figure 3
Figure 3
(a) PCA based on allele frequencies. Big green and red points are the centroids of YRI and CHB populations, respectively. Triangles represent the centroids of North African populations, whereas small circles represent the centroids of the Southern European populations. (b) Admixture analysis for K=3 ancestral components represented as pie charts. The pie chart of each population is located on its geographic position. ALP, Las Alpujarras; BED, Bedouin; BOS, Bosnia-Herzegovina; BSC, Basque Country; CHB, Han Chinese from Beijing; CHO, Chouala; CRT, Crete; GIR, Girona; JOR, Jordan; KHE, Khenifra; LIB, Libya; MZB, M'zab;SAR, Sardinia; SIC, Sicily; TOU, Toulouse; TUN, Tunisia; TUR, Turkey; VAL, Valencia; YRI, Yoruba. A full colour version of this figure is available at the European Journal of Human Genetics journal online.
Figure 4
Figure 4
Venn diagram containing the haplotypes from all the LD blocks identified in the four genomic regions studied. The population groups are Southern Europe, North Africa and Sub-Saharan Africa (Yoruba).
See this image and copyright information in PMC

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