doi: 10.1111/j.1744-313X.2009.00849.x © 2009 The Authors Journal compilation © 2009 Blackwell Publishing Ltd, International Journal of Immunogenetics 36, 207–211 207 Blackwell Publishing Ltd Detection of a novel HLA-B27 allele, B*2740, in Taiwanese volunteer bone marrow donors by sequence-based typing: curiosity rewarded M. J. Chen,* T. C. Yang,* C. C. Chu,† M. H. Shyr,* C. L. Lin,* P. Y. Lin* & K. L. Yang*‡ Summary We report here a novel HLA-B allele, B*2740, discovered in Taiwanese volunteer marrow donors. The new sequence has nucleotide variation at position 527 (T→A) as compared to B*2708. The nucleotide change caused an amino acid substitution from valine (V) to glutamic acid (E) at codon 152. Since B*2740 carries sequence confers to HLA-Bw6 public epitope we believe that this novel B*27 allele might have been generated from a gene conversion involving a Bw4-specific allele (probably B*2704) and a Bw6-specific allele. Introduction The major histocompatibility complex (MHC) of human is the human leucocyte antigen (HLA) system, which consists of several loci of genes located on the short arm of chromosome 6 at 6p21.3. These loci are classified into class I, II and III of the MHC. The proven immunological functions contributed by HLA molecules in MHC restriction and antigen presentation clearly demonstrate the vital role of these molecules in the performance of immune regulation and self-defence mechanism against microbial agents. With a vast category of polymorphism that the HLA system is being unfolded, it is imperative to precisely characterize any new allele encountered along the way of routine HLA typing procedures. HLA-B27, known to consist of at least 53 distinguish- able alleles to date (http://www.ebi.ac.uk/cgi-bin/imgt/hla/ allele.cgi, release version 2.23.0, 10 October 2008), has been reported to associate with ankylosing spondylitis (AS) or related spondyloarthropathies (SpA) (Gonzalez- Roces et al., 1997). In addition, a weak association of B27 to Behçet’s disease (Gul et al., 2002) and acute anterior uveitis (Chang et al., 2005) was also documented. The ethnicity of Taiwanese population consists of Minnan, Hakka, Mainlander and the Aborigines. Previous reports suggested that the frequency of B27 in the general Taiwanese population was about 4–8% (Chou et al., 2003; Yang et al., 2004). The most frequent HLA-B*27 subtypes in the Taiwanese B*27 population were B*2704 (86.946%), followed by B*2706 (6.964%), B*2705 (3.631%) and B*2707 (1.701%) according to our previous study (Table 1). Among all subtypes, B*2704 was the predominant allele in the AS patients in Taiwan (Yang et al., 2004; Hou et al., 2007), and the prevalence of B27 in AS patients in Taiwan was 100% (Yang et al., 2004). It was found that the frequency of B*27 corresponds to the incidence of AS in the worldwide population. It is clearly * Laboratory of Immunogenetics and Cord Blood Bank, Buddhist Tzu Chi Marrow Donor Registry, Buddhist Tzu Chi Stem Cells Centre, Buddhist Tzu Chi General Hospital, Buddhist Compassion Relief Tzu Chi Foundation, Hualien, Taiwan, † Transfusion Medicine Laboratory, Medical Research Department, Mackay Memorial Hospital, Taipei, Taiwan, and ‡ Department of Laboratory Medicine, Buddhist Tzu Chi University, Buddhist Compassion Relief Tzu Chi Foundation, Hualien, Taiwan Received 7 January 2009; revised 7 January 2009; accepted 8 April 2009 Correspondence: K. L. Yang, Laboratory of Immunogenetics and Cord Blood Bank, Buddhist Tzu Chi Marrow Donor Registry, Buddhist Tzu Chi Stem Cells Centre, Buddhist Tzu Chi General Hospital, Buddhist Compassion Relief Tzu Chi Foundation, 707, Section 3, Chung Yang Road, Hualien, Taiwan 970. Tel: +886 38561825; Fax: +886 38567851; E-mail: edward@tzuchi.com.tw The nucleotide sequence reported in this paper has been submitted to the IMGT/HLA Database and assigned the accession number HWS10005169-EU341811. The name HLA-B*2740 has been officially assigned by the WHO Nomenclature Committee in January 2008. This follows the agreed policy that, subject to the conditions stated in the most recent Nomenclature Report (Marsh et al., 2005), names will be assigned to new sequences as they are identified. Lists of such new names will be published in the following WHO nomenclature report. Table 1. Number and frequency of HLA-B27 alleles detected in unrelated healthy Taiwanese Chinese and frequency of B27 alleles in B27-positive population (Yang et al., 2004). Allele n (75,777) % of B*27 individual in general population % of B*27 allele in B*27 individuals B*2701 2 0.0026 0.046 B*2702 9 0.0119 0.207 B*2703 20 0.0264 0.460 B*2704 3783 4.9922 86.946 B*2705 158 0.2085 3.631 B*2706 303 0.3999 6.964 B*2707 74 0.0977 1.701 B*2708 a 1 0.0013 0.023 B*2711 1 0.0013 0.023 Total 4351 5.7418 100.0 a The allele B*2708 and its frequency shown here were listed prior to the discovery of B*2740 in this report.