Statistical techniques for displaying the geographical distribution of many genes in few synthetic images have been used to represent the various patterns of gene frequencies in Europe and in the world (Menozzi et al. 1978; Piazza et al. 1981 a). It has also been shown that such synthetic displays are particularly useful in detecting clines of genetic differentiation associated with movements of populations like those accompanying the Neolithic expansion of farmers from the Near East or, in more recent times, the putative diffusion of Indo-European-speaking populations (Ammerman & Cavalli-Sforza, 1984; Gimbutas, 1973). In this paper we use the same combination of statistical and graphical techniques to study the genetic structure of Italy, a European country whose unity of people and cultures was quite a recent event. The possibility of studying genetic differentiation in a small geographical area is tested and trends of genetic differences are tentatively interpreted in terms of historic and linguistic knowledge. The few demographic pieces of information taken from historical sources and compared with linguistic records support the hypothesis that the genetic structure of Italy still reflects the ethnic stratification of pre-Roman times.
Data on microgeographic population structure on four neighbouring villages of Sardinia island (Italy) are presented and discussed. Two villages are located in the lowlands where malaria from Plasmodium falciparum was endemic until the eradication of paludism. The other two villages are located in the highlands and they were malaria-free because of the altitude. Census data, inbreeding, migration matrices and surname distributions have been collected. The genetic differentiation of the four villages, tested for 31 genetic polymorphisms (106 alleles), is only in part compatible with migration rates inferred from demographic data. The possible adaptive nature of some genetic markers with respect to malarial resistance is discussed. Ambiguous results from population genetics quantitative methods do not support definite answers.
A group of 45 children affected with Coeliac Disease (CD) was typed for HLA—A, B, C, D, and DR specificities. The most significant associations were found with two alleles of the D series, with both cellular and serological typing. It is suggested that the susceptibility to CD is determined by two different genes within the HLA region, the first in common with organ‐specific autoimmune diseases and associated with Dw3, the second possibly specific for CD and associated with Dw7.
4,902 Italians were typed for HLA-A antigens, 4,721 for HLA-B and 1,503 for HLA-C. The samples, which were composed of unrelated, healthy individuals born in Italy, were used for estimating HLA-A, HLA-B and HLA-C gene frequencies with the maximum-likelihood method. Different Italian regions showed significant differences in the HLA alleles, providing further evidence for the genetic heterogeneity of the Italian population. HLA gene frequencies place continental Italy and Sicily in a position which is similar to that of other Mediterranean populations, whereas the genetic isolation of Sardinia is quite evident. The most significant linkage disequilibrium values found in the Italian population (except for Sardinia) were in agreement with those observed in other Caucasian populations. The difference between Northern and Southern Italy and between continental Italy and Sardinia was emphasized by the linkage disequilibrium values and by the principal-component analysis as well.
A sample of healthy unrelated individuals (882 from Continental Italy and Sicily, and 139 from Sardinia) were typed for HLA and Bf polymorphisms. Bf gene frequencies in Continental Italy and Sicily show an intermediate position among European populations, with Lapps on one side and Basques on the other side; while a very peculiar pattern is observed among Sardinians, with an impressive similarity with French Basques and with the highest F1 gene frequency so far observed. The HLA:Bf gametic associations in Italy and Sardinia are also reported, which confirm the different ethnic background of these populations.
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