RESUMEN
BACKGROUND: The present composition of the Ethiopian population is the result of a complex and extensive intermixing of different peoples of North African, Near and Middle Eastern, and south-Saharan origin. The two main groups inhabiting the country are the Amhara, descended from Arabian conquerors, and the Oromo, the most important group among the Cushitic people. With the exception of some surveys on the general Ethiopian populations, little is known about the degree of genetic differentiation between the Amhara and the Oromo. AIM: The study seeks to investigate the genetic structure of these two heterogeneous Ethiopian populations and to characterize their relationships with other African and Mediterranean peoples. SUBJECTS AND METHODS: Amhara and Oromo individuals (n = 171) were analysed for three RFLPs (restriction fragment length polymorphisms) of the COL1A2 gene. To better define the genetic relationship between the two Ethiopian groups, and also between African and non-African peoples, genetic distances among Amhara, Oromo and other populations were estimated using the COL1A2 allele and haplotype frequencies, and the allele frequencies of 16 additional classical markers. RESULTS: chi(2) analysis applied to the COL1A2 allele and haplotype frequencies showed a small but statistically significant degree of heterogeneity between the two Ethiopian populations. Combining the information obtained from the three RFLP markers, a significant level of differentiation (Fst = 0.0147, p = 0.036) was also detected between Amhara and Oromo. The genetic distance analysis showed the separation between African and non-African populations, with the Amhara and Oromo located in an intermediate position. This pattern is consistent with the location of the two Ethiopian groups in other genetic analysis and with cultural data. CONCLUSIONS: The present findings suggest the presence of a differential level of genetic relatedness with south-Saharan peoples in the two Ethiopian groups, which could reflect their different history and seems to indicate the existence of genetic sub-structure within the country.
Asunto(s)
Colágeno/genética , Etnicidad/genética , Polimorfismo de Longitud del Fragmento de Restricción , Alelos , Secuencia de Bases , Cromosomas Humanos Par 7/genética , Colágeno Tipo I , Etiopía/etnología , Femenino , Frecuencia de los Genes , Marcadores Genéticos , Haplotipos , Humanos , Funciones de Verosimilitud , Masculino , Datos de Secuencia Molecular , FenotipoRESUMEN
Mitochondrial DNA HV1 sequences and Y chromosome haplotypes (DYS19 STR and YAP) were characterised in an Albanian sample and compared with those of several other Indo-European populations from the European continent. No significant difference was observed between Albanians and most other Europeans, despite the fact that Albanians are clearly different from all other Indo-Europeans linguistically. We observe a general lack of genetic structure among Indo-European populations for both maternal and paternal polymorphisms, as well as low levels of correlation between linguistics and genetics, even though slightly more significant for the Y chromosome than for mtDNA. Altogether, our results show that the linguistic structure of continental Indo-European populations is not reflected in the variability of the mitochondrial and Y chromosome markers. This discrepancy could be due to very recent differentiation of Indo-European populations in Europe and/or substantial amounts of gene flow among these populations.