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.