Haptoglobin genotyping of Vietnamese: Global distribution of HP del , complete deletion allele of the HP gene Mikiko Soejima a , Tetsuro Agusa b , Hisato Iwata b , Junko Fujihara c , Takashi Kunito d , Haruo Takeshita c , Vi Thi Mai Lan e , Tu Binh Minh e , Shin Takahashi f , Pham Thi Kim Trang e , Pham Hung Viet e , Shinsuke Tanabe e , Yoshiro Koda a,⇑ a Department of Forensic Medicine and Human Genetics, Kurume University School of Medicine, Kurume, Japan b Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan c Department of Legal Medicine, Shimane University Faculty of Medicine, Enya 89-1, Izumo 693-8501, Japan d Department of Environmental Sciences, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan e Center for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Vietnam National University, T3 Building, 334 Nguyen Trai Street, Thanh Xuan District, Hanoi, Viet Nam f Department of Environmental Conservation, Faculty of Agriculture, Ehime University, Tarumi 3-5-7, Matsuyama 790-8566, Japan article info Article history: Received 16 August 2014 Received in revised form 18 August 2014 Accepted 19 August 2014 Available online xxxx Keywords: Gene deletion Geographic distribution Ancestry informative marker Anaphylaxis abstract The haptoglobin (HP) gene deletion allele (HP del ) is responsible for anhaptoglobinemia and a genetic risk factor for anaphylaxis reaction after transfusion due to production of the anti-HP antibody. The distribution of this allele has been explored by several groups including ours. Here, we studied the fre- quency of HP del in addition to the distribution of common HP genotypes in 293 Vietnamese. The HP del was encountered with the frequency of 0.020. The present result suggested that this deletion allele is restricted to East and Southeast Asians. Thus, this allele seems to be a potential ancestry informative marker for these populations. Ó 2014 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Haptoglobin (HP) is a plasma glycoprotein and is known to be one of the acute phase reactants [1,2]. It binds hemoglobin (Hb) to prevent both iron loss and kidney damage due to oxidative activity of Hb during intravascular hemolysis [3]. Humans have a genetic polymorphism of the protein due to two codominant alleles, HP 1 and HP 2 , that give rise to the three common pheno- types HP1-1, HP2-1, and HP2-2 [3]. According to this polymorphic feature, HP had been used as a genetic marker in determinations of parentage. The HP gene locates on the long arm of chromosome 16 (16q22.3) and consists of five (HP 1 ) or seven (HP 2 ) exons. HP 2 appears to have been generated by a 1.7-kb intragenic duplication of exons 3 and 4 of HP 1 . Both HP 1 and HP 2 have been found in every population examined, although their frequencies vary considerably among populations [3,4]. In addition to common polymorphisms, several rare variants of the HP phenotypes have been reported [3]. One of them is the HP-gene deletion allele (HP del ), which has an approximately 28 kb deletion extending from the HP promoter region to intron 4 of the HP-related gene. We identified HP del by genetic analysis of several Japanese cases with a negative result only for HP inheritance encountered in determinations of parentage performed in forensic practice [5]. This silent allele allows us to interpret many cases with ‘‘incompatible’’ heredity. HP del homozygotes pro- duce no HP protein and are phenotypically anhaptoglobinemic, while HP del heterozygotes have a lower amount of HP protein in their serum than those without HP del [5,6]. HP del homozygotes have a risk of undergoing anaphylactic transfusion reactions if they produce HP antibodies [7]. Because washed red blood cells and platelet concentrate are effective in preventing transfusion-related anaphylactic reactions [8], we have developed several simple methods to detect this allele before transfusion [7,9–11]. A series of studies by several groups including us have found HP del in East and Southeast Asian populations but not in others [6,7,9,12–17]. For better understanding of the distribution of this allele in order to prevent serious problems in clinical practice and to determine whether it can be used as one of the ancestry informative markers, we determined the HP genotypes of a Vietnamese population in this study. http://dx.doi.org/10.1016/j.legalmed.2014.08.004 1344-6223/Ó 2014 Elsevier Ireland Ltd. All rights reserved. ⇑ Corresponding author. Address: Department of Forensic Medicine and Human Genetics, Kurume University School of Medicine, Kurume 830-0011, Japan. Tel.: +81 942 31 7554; fax: +81 942 31 7700. E-mail address: ykoda@med.kurume-u.ac.jp (Y. Koda). Legal Medicine xxx (2014) xxx–xxx Contents lists available at ScienceDirect Legal Medicine journal homepage: www.elsevier.com/locate/legalmed Please cite this article in press as: Soejima M et al. Haptoglobin genotyping of Vietnamese: Global distribution of HP del , complete deletion allele of the HP gene. Leg Med (2014), http://dx.doi.org/10.1016/j.legalmed.2014.08.004