HLA polymorphism in Lombardy defined by high-resolution typing methods

Background - Population data on the HLA system are important to several areas of medicine and science. HLA-A*, B*, C*, DRB1* and DQB1* allele and haplotype frequencies in 105 unrelated healthy Italian individuals from Lombardy were estimated. Methods - Commercial kits with sequence-specific primers designed to match single alleles were used for specific primer polymerase chain reactions (PCR-SSP) to determine HLA class I (HLA-A*, B* and C* loci) and class II (HLA-DRB1*, DQB1* loci) alleles. For HLA-DRB1* single allele-specific amplification and sequencing was also used separately, using a Protrans S4 commercial kit. Results - A total of 16 HLA-A*, 22 HLA-B*, 14 HLA-C*, 20 DRB1* and 12 DQB1* alleles showing a frequency >1% were identified at the four-digit level in the population. The highest frequency alleles included A*02:01 (13.3%), B*51:01 (9.5%), C*04:01 (20.5%), DRB1* 11:01 (13.8%) and DQB1*03:01 (33.8%). The most frequent extensive haplotype was A*01:01-C*07:01 B*08:01-DRB1*03:01-DQB1*02:01 with a haplotype frequency of 2.4%. Conclusions - The present findings could be useful to elucidate the genetic background of the population, and to provide data for HLA matching in clinical transplantation, information on the distribution of HLA genotypes in different populations for the development of peptidebased vaccines, and information for paternity diagnosis and on evolutionary factors such as genetic drift, migration and selection.