HLA B27 Subtype Distribution Among Patients with Ankylosing Spondylitis in Eastern Turkey Eda Diyarbakir, 1 Nilnur Eyerci, 1 Meltem Melikoglu, 2 Atilla Topcu, 1 and Ibrahim Pirim 1 Human leukocyte antigen (HLA) B27 has a strong association with ankylosing spondylitis (AS) and other spon- dyloarthropathies. More than 70 subtypes of HLA B27 have been described. The present study investigated B27 subtype distribution among B27-positive patients with AS classified according to the modified New York criteria and healthy controls. Sequence-specific primer polymerase chain reaction technique was used for B27 subtyping of 43 unrelated patients with AS and 39 volunteer bone marrow donors. Among patients with AS, the male–female ratio was 6.2 and the mean age was 30 years. No relationship was found between the B27 subtypes and clinical and laboratory findings in patients with AS ( p > 0.05). Similarly, the frequencies of B27 subtypes did not significantly differ between patients and controls. In this study, B*2746, B*2749, and B*2767 subtypes were detected for the first time. Among B27 subtypes, the most common B27 alleles found in the patients and the controls were B*2702 and B*2705. In addition, B*2702 subtype was found predominantly in both patients (48.8%) and controls (46.2%). In conclusion, in addition to commonly encountered B*2702 and B*2705 HLA subtypes, a B*2749 subtype in a patient with AS and B*2746 as well as B*2767 subtypes in controls were determined for the first time. Introduction M any rheumatic diseases result from the interaction of environmental and genetic factors. During the past 30 years, the definition of the association of B27 with anky- losing spondylitis (AS) has served as a milestone for research about the association of HLA and other genetic markers with spondyloarthropathies. However, the exact role of B27 in the etiology of AS is not completely understood. B27-positive individuals may not develop AS or other spondyloar- thropathies, and 5–10% of patients with AS are negative for B27. There are few data in the literature about which triggers initiate spondylitis in the individuals with a genetic tendency (Akkoc and Khan 2008). By now, more than 70 molecular subtypes of B27 have been described . Most of these subtypes differ from each other only by the properties of peptide-binding molecules of a few amino acids (IMGT/HLA Database 2011). The distribution of B27 subtypes varies depending on ethnicity and geographic distributions (Khan and Ball 2002). Generally, HLA B*2705 is the most common subtype in all populations. HLA B*2702 exists in Asia and in certain coun- tries of northern Africa, Europe, and the Mediterranean; it is reported to be the most common subtype among Caucasian and Arab populations (Khan et al., 2007). Several studies found that B*2705, B*2702, B*2704, and B*2707 are the sub- types predisposing to AS. B*2704 is the most commonly encountered subtype among Chinese and Japanese popula- tions (Lin et al., 1996; Reveille 2006). AS is a chronic progressive inflammatory disease that usually affects men (Bodur et al., 2010). On the basis of the data in the literature, it is not possible to determine whether HLA B27 subtypes in female patients help protect against this disease. This study sought to determine B27 subtypes of B27- positive patients with AS and healthy controls. The local ethics committee approved this study. Materials and Methods Patient selection This study included 43 patients with AS (37 men and 6 women) selected from referrals to the Rheumatology Poli- clinic of the Training and Research Hospital in Erzurum, eastern Turkey. The patients were diagnosed with and given medical treatment for AS according to the modified New York criteria, were unrelated, and were positive for the B27 allele. Control population The 39 control participants (27 men and 12 women) were selected among unrelated persons who had applied to our laboratory to be bone marrow donors and had previously been determined to be B27 positive. AS, reactive arthritis, 1 Faculty of Medicine, Department of Medical Biology, Ataturk University, Erzurum, Turkey. 2 Department of Rheumatology, Erzurum Training and Research Hospital, Erzurum, Turkey. GENETIC TESTING AND MOLECULAR BIOMARKERS Volume 16, Number 5, 2012 ª Mary Ann Liebert, Inc. Pp. 456–458 DOI: 10.1089/gtmb.2011.0183 456