High Variability of HLA-B27 Alleles in Ankylosing Spondylitis and Related Spondyloarthropathies in the Population of Northern Spain Segundo Gonzalez, Sonia Garcia-Fernandez, Jesus Martinez-Borra, Miguel Angel Blanco-Gelaz, Luis Rodrigo, Jose Sanchez del Rı ´o, Antonio Lo ´ pez-Vazquez, Juan Carlos Torre-Alonso, and Carlos Lo ´ pez-Larrea ABSTRACT: The distribution of B27 alleles (B*2701- 23) was characterized by PCR-SSP in ankylosing spondy- litis and related spondyloarthropathies (SpA) in a sample of B27 positive patients from northern Spain. Six B27 alleles were identified: B*2705,02,03,07,08 and B*2713. B*2705 and 02 were the most common alleles in the SpA studied: ankylosing spondylitis (AS) (n = 89), reactive arthritis (ReA) (n = 11), psoriatic arthritis (PsA) (n = 29), and inflammatory bowel disease (IBD) (n = 21). B*2707 and B*2708 were found in PsA patients and B*2703 in one patient with IBD. B*2713 was identified in a healthy control family. B*2713 has not been reported to be represented in either ethnic group. Thus, this pop- ulation shows higher levels of B27 diversity than other Caucasian groups. Human Immunology 63, 673– 676 (2002). © American Society for Histocompatibility and Immunogenetics, 2002. Published by Elsevier Science Inc. KEYWORDS: HLA-B27 alleles; spondyloarthropathy; ankylosing spondylitis; PCR-SSP ABBREVIATIONS HLA human leukocyte antigen SpA spondyloarthropathies PsA psoriatic arthritis AS ankylosing spondylitis IBD inflammatory bowel disease PCR-SSP polymerase chain reaction–sequence- specific primer ReA reactive arthritis INTRODUCTION The SpA constitute a group of disorders with common genetic and clinical characteristics. The common denom- inator in the multiple disorders included in this group is a genetic predisposition associated with HLA-B27. Clin- ical evidence suggests that individuals with B27 may exhibit a higher frequency of axial involvement. The strength of the disease association with B27 varies mark- edly, both among the various spondyloarthropathies (SpA) and also among racial and ethnic populations [1]. This range among the different spondyloarthropathies from about 20% in the case of psoriatic arthritis to over 95% in ankylosing spondylitis. Considerable differences have been described in the distribution of B27 alleles and ankylosing spondylitis (AS) in different populations [2], but few studies have characterized the B27 polymor- phism in related SpA. Nevertheless, it is important to know whether certain subtypes show any preferential association with the different clinical forms of SpA. The number of B27 alleles reported has rapidly risen From the Functional Biology Department (S.G.), University of Oviedo, Oviedo; the Departments of Immunology (S.G.-F., J.M.-B., M.A.B.-G., A.L.-V., C.L.-L.), Gastroenterology (L.R.), and Dermatology (A.J.S.R.), Hospital Central de Asturias, Oviedo; and the Rheumatology Unit (J.C.T.- A.), Hospital Monte Naranco, Oviedo, Spain. Address reprint requests to: Dr. Carlos Lo ´pez-Larrea, Department of Immunology, Hospital Central de Asturias, E-3006 Oviedo, Spain; Fax: +34 (985) 106142; E-mail: inmuno@hca.es. Received October 2, 2001; revised March 15, 2002; accepted March 22, 2002. Human Immunology 63, 673– 676 (2002) © American Society for Histocompatibility and Immunogenetics, 2002 0198-8859/02/$–see front matter Published by Elsevier Science Inc. PII S0198-8859(02)00404-4