HLA-A, -B and -DRB1 allele frequencies in Cyrenaica population (Libya) and genetic relationships with other populations Andrea Galgani a , Giorgio Mancino b , Cristina Martínez-Labarga c , Rosella Cicconi a , Maurizio Mattei a , Massimo Amicosante d , Cesira T. Bonanno e , Caterina Di Sano f , Giuma Salem Gimil g , Alfredo Salerno e , Vittorio Colizzi c , Carla Montesano c,⇑ a Centro di Servizi Interdipartimentale, Stazione per la Tecnologia Animale, University of ‘‘Tor Vergata’’, Rome, Italy b Research Center, ‘‘S. Pietro’’ Hospital, Fatebenefratelli, Rome, Italy c Department of Biology, University of ‘‘Tor Vergata’’, Rome, Italy d Department of Biomedicine and Prevention, University of ‘‘Tor Vergata’’, Rome, Italy e Department of Pathology and Biomedical Methodologies, University of Palermo, Italy f Institute of Biomedicine and Molecular Immunology, National Research Council, Palermo, Italy g Hematology Department of Tripoli Medical Center, Tripoli, Libya article info Article history: Received 12 December 2011 Accepted 3 October 2012 Available online 16 October 2012 abstract The frequencies of HLA-A, HLA-B and HLA-DRB1 alleles in 118 unrelated Libyans from Benghazi (Cyrena- ica) were analysed using high resolution typing and compared with other populations. Their relatedness has been tested by correspondence analyses and principal component analysis. The most frequent HLA-A alleles were A / 02:01:01:01 (15.7%), A / 01:01:01:01 (11.4%) and A / 03:01:01:01 (9.3%). For the HLA-B locus, the commonest allele was HLA-B / 50:01:01 (14.4%) followed by B / 51:01:01 (9.8%) and B / 08:01:01 (6.4%). For the HLA-DRB1 locus, the commonest was HLA-DRB1 / 07:01:01:01 (16.9%) followed by DRB1 / 03:01:01:01 (13.6%) and DRB1 / 13:02:01 (9.3%). The most frequent two-locus haplotypes were HLA-A / 02:01:01:01-B / 07:02:01 (3.0%) and HLA-B / 50:01:01-DRB1 / 07:01:01:01 (9.6%), and three-locus haplotypes were HLA-A / 02:01:01:01-B / 50:01:01-DRB1 / 07:01:01:01 (4.2%) and HLA-A / 11:01:01- B / 52:01:01:01-DRB1 / 15:02:01 (2.5%). This study is the first on the HLA status of a Libyan population. The results, when compared to similar HLA data obtained previously from African and Mediterranean populations, indicate genetic influences from several ethnic groups. Moreover, the differences in the HLA allele frequencies between the Libyan population and others reveals that significant admixture has occurred between the original Berber inhabitants and neighbouring and more distant populations, even though a strong genetic Berber substratum remains. These data will be of value to future anthropo- logical and disease association studies involving the Libyan population. Ó 2012 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved. 1. Introduction The Human Leukocyte Antigen (HLA) is the most polymorphic gene cluster in humans. It plays a key role in the presentation of antigenic peptides to CD4+ and CD8+ T-lymphocytes that initiate the immune response. Sequence polymorphism in the antigen- binding domains of the HLA molecules determine the repertoire of peptides that can be presented and in turn influence an individ- ual’s immune response [1]. According to the ImMunoGeneTics (IMGT)/HLA database (as of August 2012) (http://www.ebi.ac.uk/ imgt/hla/), 8016 HLA alleles have been described from various hu- man populations around the world [2]. These genes are located on the short arm of human chromosome 6 (6p21.3). The frequencies of the various HLA alleles, and their linkage disequilibrium pat- terns, differ significantly among different human populations [3]. Knowledge of this genetic system is helpful in organ and in haema- topoietic stem cell transplantation, vaccine development, and dis- ease association. In anthropological studies, the usefulness of HLA for assessing genetic relationships among populations has been widely used and validated to establish or corroborate migration and admixture patterns [4–6]. However, limited information is available on the distribution of HLA alleles in some countries and/or ethnic groups, in particular those from Africa including Libya [7]. Berber tribes were the first inhabitants of Libya. In the 7th cen- tury B.C., the Phoenicians colonized the eastern parts of Libya, called Cyrenaica, while the Greeks colonized the western portion, called Tripolitania. Cyrenaica fell under the control of the Roman 0198-8859/$36.00 - see front matter Ó 2012 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.humimm.2012.10.001 ⇑ Corresponding author. Address: Department of Biology, University of ‘‘Tor Vergata’’ Via della Ricerca Scientifica 1, 00133 Rome, Italy. Fax: +39 0672594224. E-mail address: montesano@uniroma2.it (C. Montesano). Human Immunology 74 (2013) 52–59 Contents lists available at SciVerse ScienceDirect www.ashi-hla.org journal homepage: www.elsevier.com/locate/humimm