Genetic analysis of a Sicilian population using 15 short tandem repeats

Human Biology, Apr 2003 by Calo, C M, Garofano, L, Mameli, A, Pizzamiglio, M, Vona, G

Data for comparison have been taken from the following European and Mediterranean countries: from Spain, the Basque Country (Perez-Lezaun et al. 2000), Catalonia (Gene et al. 1998; Gene et al. 2000), and Andalusia (Perez-Lezaun et al. 2000); from Italy, Lombardy and Tuscany (Barbara et al. 2000); from other countries, Portugal (Pinheiro et al. 2000), Switzerland (Gehrig 1998), Poland (Miscika-Sliwka et al. 1998), Germany (Hantshel et al. 1999; Seidl et al. 1998), Hungary (Furedi et al. 2000), Egypt (Klintschar et al. 1998; Klintschar et al. 1999), and Morocco (Perez-Lezaun et al. 2000). The genetic diversity involving these were calculated by use of the G^sub ST^ coefficient according to Nei (1973) (Table 3), with values ranging between 0.006 (D5S818) and 0.046 (D8S1179). Comparing all the observed values for the European and Mediterranean populations, it is possible in all cases to observe, with the exception of D8S1179, that the G^sub ST^ values for Sicily exceed those obtained for the compared populations. As a result, the overall G^sub ST^ calculated for the nine STRs for Sicily resulted in a value of 0.025 in contrast to 0.017 for the other compared populations.

Genetic distances calculated with the Nei method (1972) are reported in Table 5. It was observed that the smallest distance lay between Germany and Hungary (0.0099) in comparison to the largest distance, which was between Palermo and Lombardy (0.2356). With regards to the Alia sample, distances varied between 0.0310 (Alia-Hungary) and 0.1506 (Alia-Palermo), respectively.

The tree generated from the matrix, shown in Figure 2, compares the populations. The populations are located in two separate groups. One group consists of all the Sicilian populations and the Egyptian population, with the exception of Alia. It is worth observing that the Sicilian populations appear quite scattered in the tree with Palermo located on an isolated branch. The second group shows some associations in particular; the populations of Morocco and Andalusia are located together on a separate branch, as well as those of the Basque Country and Catalonia. The population of Alia is associated with those of Poland and Hungary. In comparison to the other populations, the populations of the Basque Country and of north and central Italy occupy a particular position.

Using the Delauney network, three genetic boundaries have been discovered (Figure 3). The first of these boundaries stretches from northern to southern Sicily and divides the island into two separate sections. The second boundary is shorter, separating Alia from the main center (Palermo). The third seems to divide Sicily from north-central Italy and from the other western Mediterranean populations.

Discussion

Using the allele frequencies of 15 STRs we were able to gather new data to aid in the analysis of the genetic structure for the population of Alia, a small village located along the interior of the mountainous chain of Madonie in Palermo, the main district of Sicily, Italy. The recent discovery of skeletal remains of victims of an 1837 cholera epidemic has brought a number of anthropologists, population geneticists, and demographers to Alia, not just for the skeletal remains but also because of the village's geographical and economic isolation (Bigazzi 2000; Vona et al. 2001; Ghiani et al. 2002). Results from analyses of classical markers (Ghiani at al. 2002) and mtDNA (Vona et al. 2001) showed that the genetic structure of Alia differed from that of other Sicilian and Mediterranean populations.