HLA Class I and Class II Polymorphism in Three Sicilian Populations
Two human leukocyte antigen (HLA) class I loci (HLA-A and HLA-B) and one class II locus (HLA-DR) were typed at the DNA level in the Sicilian population. Study participants were of Sicilian origin (183 for class I loci and 260 for class II loci) and live in three towns, chosen on the basis of geographic position and different historical events. These towns are Sciacca (southwest Sicily, located at sea level, conquered by Arabs in A.D. 814), Piana degli Albanesi (northwest Sicily, 720 m above sea level, has maintained religious, cultural, and linguistic peculiarities traced to Albanian settlement in 1488), and Troina (northeast Sicily, 1,120 m above sea level, known as the first settlement of Normans). The assumptions underlying the study of genetic structure, based on HLA allele polymorphism, are that these three towns are located in areas that can be distinguished according to historical criteria and that they are likely to have contributed to cultural and probably genetic differences. As such, the high frequency of some alleles in Sciacca and Troina seems to be correlated with Greek, Phoenician, North African, and Arab influence. In accordance with different human settlements in Sicily, we found that the HLA allele frequencies support the existence of genetic differentiation between the western and eastern sides of Sicily. This separation is attributed to Greek colonization in the east and to Phoenician-Carthaginian-Arab influence in the west. Moreover, the comparisons of all allele frequencies between Mediterranean and African populations show the same trend, highlighting in some cases European origin and in other cases non-European origin.
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Sciacca is located on the southwestern side of Sicily and belongs to the province of Agrigento. Its origin has been traced as far back as 628 B.c. The mythical founder of the city is said to have been Kokalos, king of the Sicani. Sciacca is one of the most ancient thermal resorts in the Mediterranean. It was known in Siceliot times for its sweating caves and for its thermal waters, and the Romans gave it the name Thermae Selinuntinae, or Aquae Larodae. In A.D. 814 Arabs conquered Sciacca and called it as-Shaqqah (hence the current name Sciacca). Arab domination seems to have had a strong genetic impact, in that it modified the demographic distribution of the town. The urban structure also gives evidence of a later settlement of a large Jewish community inside the quarter of Cadda, which had a near monopoly on dyeing and silk weaving.
Hum Biol. 2007 Jun;79(3):339-54.
HLA in Sicilians
Since HLA genes constitute a relatively tiny portion of the genome and are subject to strong selection pressure, I give comparatively little weight to population affinities derived from HLA haplotypes. The following study may be worth reading mainly for the historical overview. It would be useful to conduct a similar study using high-resolution SNP genotypes.