Allele frequencies of 13 short tandem repeats in population samples from the Iberian Peninsula and northern Africa

Keratoconus in 18 pairs of twins

PURPOSE

To describe the concordance of keratoconus in 18 sets of twins.

METHODS

Thirteen monozygotic (MZ) and five dizygotic (DZ) pairs of twins were identified during an investigation of familial keratoconus. We used 16 forensic microsatellite markers to confirm the zygosity of same sex twins. Patients and available relatives were examined for signs of keratoconus using corneal topography. For each pair of twins, the severity of keratoconus in each eye was graded according to the steepest keratometry value and the average difference in score between the MZ and DZ twins compared.

RESULTS

All of the MZ twins and four of the five DZ twins were concordant for keratoconus but with differences in age of onset and severity of disease. The subjective age of onset of keratoconus tended to be earlier in the MZ twins (16.4 years, SD 4.66) than in the DZ twins (20.3 years, SD 7.55) (p=0.086). Additional relatives with keratoconus were identified in two (16%) of the families with MZ twins and in three (60%) of the families of DZ twins. The mean difference in severity scores was 1.4 (SD 1.73) for the MZ twins and 3.0 (SD 1.00) for the DZ twins (p=0.035).

CONCLUSION

This data provide evidence that the severity of keratoconus is more concordant in MZ than in DZ twins. The results support the currently accepted hypothesis of an important genetic contribution towards the pathogenesis of keratoconus, but suggest that there is also an environmental effect on the expression of disease.

Paternal genetic history of the Basque population of Spain

This study examines the genetic variation in Basque Y chromosome lineages using data on 12 Y-short tandem repeat (STR) loci in a sample of 158 males from four Basque provinces of Spain (Alava, Vizcaya, Guipuzcoa, and Navarre). As reported in previous studies, the Basques are characterized by high frequencies of haplogroup R1b (83%). AMOVA analysis demonstrates genetic homogeneity, with a small but significant amount of genetic structure between provinces (Y-short tandem repeat loci STRs: 1.71%, p = 0.0369). Gene and haplotype diversity levels in the Basque population are on the low end of the European distribution (gene diversity: 0.4268; haplotype diversity: 0.9421). Post-Neolithic contribution to the paternal Basque gene pool was estimated by measuring the proportion of those haplogroups with a Time to Most Recent Common Ancestor (TMRCA) previously dated either prior (R1b, I2a2) or subsequent to (E1b1b, G2a, J2a) the Neolithic. Based on these estimates, the Basque provinces show varying degrees of post-Neolithic contribution in the paternal lineages (10.9% in the combined sample).

Autosomal short tandem repeat genetic variation of the Basques in Spain

Aim

To examine population genetic structure and hypotheses of the origin of the modern Basque population in Spain using autosomal short tandem repeat (STR) data from individuals living in 27 mountain villages in the provinces of Alava, Vizcaya, Guipuzcoa, and Navarre, by comparing Basque autosomal STR variation with that of neighboring populations in Europe, as well as proposed ancestral populations in North Africa and the Caucasus.

Methods

Allele frequencies for 9 autosomal STR loci (D3S1358, D5S818, D7S820, D8S1179, D13S317, D18S51, D21S11, FGA, and vWA) and several population genetic parameters were determined for the 4 provinces in the Basque region of Spain (n = 377). Heterozygosity within the Basque population was measured using a locus-by-locus analysis of molecular variance. Relationships between the Basques and other populations were examined using a multidimensional scaling (MDS) plot of Shriver’s D_SW distance matrix.

Results

Heterozygosity levels in the Basque provinces were on the low end of the European distribution (0.805-0.812). The MDS plot of genetic distances revealed that the Basques differed from both the Caucasian and North African populations with respect to autosomal STR variation.

Conclusions

Autosomal STR analysis does not support the hypotheses of a recent common ancestor between the Basques and populations either from the Caucasus or North Africa.

Allelic frequencies of the 15 STR loci included in the AmpFlSTR® Identifiler™ PCR Amplification Kit in an autochthonous sample from Spain

The aim of this study was to estimate the allelic frequencies of the 15 STR loci included in the AmpFlSTR Identifiler PCR Amplification Kit in a sample of 342 unrelated Caucasian individuals autochthonous from Spain to be used for forensic purposes and population studies. The combined power of discrimination and the combined power of exclusion for all of the 15 loci were 5.68x10(-18) and 0.9999964, respectively. According to the obtained data, the D18S51 locus may be considered the most informative among the tested loci.

Allele frequencies of 15 tetrameric short tandem repeats (STRs) in Andalusians from Huelva (Spain)

The allele frequency distribution of 15 short tandem repeat (STR) loci contained in the AmpFlSTR Identifiler PCR Amplification Kit (Applied Biosystems), was determined in 114 individuals from Andalusia (province of Huelva), in the southernmost part of the Iberian Peninsula. After Bonferroni's correction, no deviations from the Hardy-Weinberg equilibrium were observed for all samples at the 15 STR loci. All loci are highly polymorphic. The aim of the study was to obtain accurate allele frequencies relevant for applications in forensics and population genetics. Comparative analyses between our population data and other population samples gathered from the literature are also presented.

13 STR loci frequencies in the population from Paraíba, Northeast Brazil

As part of a long-term project on Northeastern Brazilians, population genetic data were obtained from 323 unrelated individuals from the state of Paraíba. The loci studied were CSF1P0, TPOX, TH01, vWA, D16S539, D7S820, D13S317, D18S51, D21S11, D8S1179, F13A01, F13B and LPL. Their distributions are in Hardy-Weinberg equilibrium. Forensic parameters were calculated and a comparison was made with geographically nearby populations.

Genetic diversity of 10 X chromosome STRs in northern Portugal

Genetic data of 10 X chromosome STRs (DXS8378, DXS9898, DXS8377, HPRTB, GATA172D05, DXS7423, DXS6809, DXS7132, DXS101 and DXS6789) were obtained in a sample of unrelated males born in the five northern Portuguese districts. In a global sample of 347 individuals, no shared haplotypes were found for this set of markers and single locus gene diversities were high, varying between 0.678 for DXS7423 and 0.921 for DXS8377. Linkage disequilibrium analysis did not reveal consistent evidence of association between the X-STRs used. Population comparisons of northern Portuguese districts (exact test of population differentiation; pairwise genetic distances) and analysis of molecular variance supported genetic homogeneity of this region and therefore a common genetic database was considered. In comparisons with other European data, the only population samples showing statistically significant differences to northern Portugal were Germany and Latvia. The present work demonstrates that these genetic markers are highly discriminating and therefore useful for human identification purposes and anthropological research.

Population genetic data of 15 tetrameric short tandem repeats (STRs) in Berbers from Morocco

The allele frequency distribution of 15 short tandem repeats (STR) loci contained in the AmpFlSTR Identifiler PCR Amplification Kit (Applied Biosystems), was determined in two Berber populations from Asni and Bouhria, in Central and Eastern Morocco, respectively. A total of 209 individuals were typed. No deviations from the Hardy-Weinberg equilibrium were observed for Asni at the 15 STRs loci whereas for the Bouhria samples, two loci (D5S818 and TH01) showed significant departures from Hardy-Weinberg expectations (after Bonferroni's correction). All loci are highly polymorphic and population differentiation tests showed that the Moroccan samples from Asni and Bouhria have significant differences in 4 out of 15 loci (D21S11, D7S820, D16S539 and TPOX). The aim of the study was to obtain accurate allele frequencies relevant for forensic applications. Comparative analyses between our population data and other population samples gathered from the literature are also presented.

Differential maternal and paternal contributions to the genetic pool of Ibiza Island, Balearic Archipelago

We report on a comparison of the genetic diversity between Ibiza and the population of the other Balearic islands and also between the archipelago with respect to circum-Mediterranean populations. For such a comparison, autosomal and Y-chromosome STRs, as well as mtDNA sequence data analyzed from the same individuals, were studied. Analysis of 14 autosomal STRs showed that Ibiza had significant differentiation with respect to other Balearic populations and also with respect to insular and continental populations from the Mediterranean area. Nevertheless, the results obtained from the analysis of eight Y-STRs showed a high level of genetic homogeneity for eight western Mediterranean populations. On the other hand, these populations did not show a compacted group when mtDNA diversity was analyzed, since they showed genetic differentiation among them. The analyses of haplotypes shared between populations indicated that mtDNA haplotypes have drifted to higher frequencies than the Y chromosome. This fact could be due to a shared recent history between Ibiza and other western Mediterranean populations, with numerous male displacements originated by wars and, especially, commercial relations. The results of mtDNA from the Ibiza population could be due to a maternal Carthaginian/Phoenician founder effect, together with genetic drift, in accordance with the historical and demographic data of the area.

Allelic frequencies of 13 STR loci in autochthonous Basques from the province of Vizcaya (Spain)

Allelic frequencies of 13 STR loci (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D16S539, TH01, TPOX, CSF1PO, and D7S820) were estimated from a sample of 73 unrelated healthy donors natives of the Spanish Basque province of Vizcaya. These STR loci constitute the core of polymerase chain reaction (PCR)-based DNA genetic markers in the US Combined DNA Index System (CODIS). All STR loci analysed met Hardy-Weinberg expectations. Based upon the allelic frequencies, forensically important parameters including gene diversity (GD), polymorphism information content (PIC) and power of discrimination (PD) were calculated.

Genetic data on 13 STR loci in the Andalusian (South Spain) population

The aim of this paper was to obtain allelic frequencies for the 13 CODIS core STR loci (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D16S539, TH01, TPOX, CSF1PO, and D7S820) from autochthonous individuals from Andalusia, Spain. In addition, a number of forensically useful genetic parameters are reported.

Genetic structure of a Cuban population based on nine short tandem repeat loci

Cuba is a multiethnic and multiracial society. Here we describe the genetic variation of a sample of the Cuban population, which include the three most common racial groups, Caucasians, Negroids and Mestizos, by means of a set of nine microsatellites (HUMTH01, HUMTPOX, HUMCFS1PO, HUMVWA, HUMFESFPS, HUMF13A, HUMF13B, HUMLPL and HUMHPRTB). The analysis presented here indicates that these STR loci are highly informative for forensic purposes. The genetic data on the major racial groups is in good agreement with current demographic tendencies and with historic events that took place during the formation of the Cuban population.

Study of GM immunoglobulin allotypic system in Berbers and Arabs from Morocco

The GM immunoglobulin allotype polymorphism was investigated in four Moroccan populations: three Berber groups from Khenifra (Middle Atlas), Amizmiz (High Atlas), and Bouhria (Beni Snassen) and one Arabic-speaking sample from the Doukkala area (Abda, Chaouia, Doukkali, and Tadla districts in south-central Morocco). In order to characterize the genetic relationships between the populations, our results were compared with those obtained for other North African groups (from Morocco, Algeria, Tunisia, and Niger) and for Middle-East Africans, sub-Saharans, and Southwest Europeans. Based on GM haplotype frequencies, Factorial Correspondence Analyses, F(ST) significance testing, and hierarchical analyses of variance were performed. Our results reveal that Moroccan populations have heterogeneous GM profiles with high frequencies of GM haplotypes in Europeans (from 76% for Doukkala to 88% for Bouhria) and relatively high frequencies of GM haplotypes in sub-Saharans (from 11% for Bouhria to 23% for Amizmiz). The genetic diversity observed among Moroccans is not significantly correlated with either geographic or linguistic differentiation. In spite of their cultural and historical differentiation, we did not discover any significant genetic differences between Berbers and Arabic-speakers from Morocco. However, when large geographical areas are considered, our population samples are integrated in the North African GM variation, significantly distant from sub-Saharan groups but with a close relationship with Southwest European populations.

Genetic differentiation of the Cabo Verde archipelago population analysed by STR polymorphisms

Allele frequencies for 17 STR loci were analyzed in a sample of unrelated males from the Cabo Verde Archipelago. The samples were gathered in such a way that the origin of the subjects was perfectly identified, and they could be included in one of the leeward or windward groups of islands. This study reveals that there are significant differences between both groups of islands, and between Cabo Verdeans and other populations from sub-Sahara Africa including the Guineans, the most probable source population for Cabo Verdeans. This study confirms mtDNA data and, together with HLA and Y chromosome data already published, shows that the Cabo Verde population is sub-structured and atypical, diverging substantially from mainland sub-Saharan populations. Overall these differences are most probably due to admixture between sub-Saharan slaves brought into the islands and other settlers of European origin. In the absence of a clear indication of a different ethnic composition of the first sub-Saharan settlers of Cabo Verde, the differentiation exhibited in both groups of islands can be most probably be attributed to genetic drift.

Population genetic data of eight tetrameric short tandem repeats (STRs) in Casablanca resident population to use in forensic casework

The allele frequencies for eight short tandem repeat (STR) loci HUMvWA, HUMFES/FPS, HUMF13A, HUMF13B, HUMTHO1, HUMTPOX, HUMCSF1P0, HUMLPL included in Geneprint STR kits were obtained from 234 unrelated individuals in Casablanca.

Genetic profile of the Açores Archipelago population using the new PowerPlex 16 system kit

Allele and haplotype frequencies of 16 chromosome STR loci, 15 of them included in the Kit PowerPlex16 System from Promega were determined in a sample of unrelated males from the Açores Archipelago. All subjects were subjected to an interview in order to make sure that their ancestors belonged to the same island at least back to three generations. This way we intended to look for possible inter-islands differences. PowerPlex16 includes STRs not studied before in the Açores population. The Kit includes two new allele markers (Penta D and Penta E), which proved to be extremely useful for paternity testing (PD=0.921 and 0.971, respectively). The study revealed that the Açores population is considerable different from the previous studied Madeira population, but does not differ from that of the north Portugal. Nevertheless, some loci presented alleles not previously reported for Portugal.

Genetic profile of a multi-ethnic population from Guiné-Bissau (west African coast) using the new PowerPlex 16 System kit

Allele and haplotype frequencies of 15 chromosome STR loci included in the kit PowerPlex16 System from Promega, were determined in a sample of unrelated males from Guiné-Bissau, a country from the west African coast. All individuals were subjected to an interview in order to make sure that their ancestors belonged to the same ethnic group. This way we intended to look for possible inter-ethnic differences. PowerPlex 16 includes STRs not studied before in any multi-ethnic population. The kit includes two new allele markers (Penta D and Penta E), which are very useful either in forensics or population genetic studies. The Guinean population presents significant differences when compared with other African populations.