Characterization of Two Polymorphic Sites in the Human Kinin Receptor Gene: Altered Frequency of an Allele in Patients with a History of End-Stage Renal Failure DIMCHO R. BACHVAROV,* MICHELLE LANDRY,* ISABELLE PELLETIER,* MARIO CHEVRETTE,t CHRISTINE BETARD,t ISABELLE HOUDE,* JEAN BERGERON,* MARCEL LEBEL,* and FRANOIS MARCEAU* *Ce,itre Hospitalier Universitaire de Qu#{233}bec, Centre de Recherche du Pavillon l’H#{244}tel-Dieu de Qu#{233}bec Qu#{233}bec, Canada; and General Hospital Research Institute, Montreal, Qu#{233}bec, Canada. Abstract. On the basis of the genomic structure of the human B1 receptor (B1R) for kinins, the presence of possible allelic polymorphisms of this gene was investigated using restriction fragment-length polymorphism and single-strand conformation polymorphism. The frequencies of the found alleles were de- termined in healthy volunteers and in patients with a history of end-stage renal failure, because there is evidence for a nephro- protective action of the kallikrein-kinin system. An A’#{176}8 - 0 polymorphism has been identified in exon 3 in a minority of volunteer blood donors, and is located 35 nucleotides down- stream from the stop codon and 14 nueleotides upstream from the polyadenylation signal. The frequency of the 0 allele is 4.4% in the control sample and not significantly altered in patients with a history of end-stage renal failure. A second and more frequent polymorphism ( I 8. 1% of the alleles in the control group, prevalence of 33.3%) consists of a single base substitution (G_699 - C) in the putative promoter region. This polymorphism is significantly less frequent in the population of renal failure patients (prevalence of 20.6%) and determines an increased activity of the promoter function in constructions involving a reporter gene. The altered prevalence of this allele was also found in some etiologic subgroups of uremic patients. This study confirms the mapping of the B1R gene to l4q32. Other investigators have mapped the bradykinin B2 receptor (B,R) gene to a close site on human chromosome 14. A previously described B2R polymorphism (exon 2, C18’ T) had an allele frequency of 9.7% in the control sample and appears to be clinically neutral. The polymorphism of the B 1R promoter may be a marker of prognostic significance for the preservation of renal function in diseased individuals. (J Am Soc Nephrol 9: 598-604, 1998) Bradykinin (BK) and sequence-rebated peptides (hereafter termed “kinins”) are blood-derived peptides that are suspected to be inflammatory mediators and renal function mediators ( 1). Indeed, exogenous BK induces vasodilation, pain, increased vascular permeability, and increased production of eieosanoids and nitric oxide by endothelial cells. The renal kallikrein-kinin system is especially activated by a dietary excess of NaCI and contributes to natriuresis and diuresis (1 ). There is also cvi- dence that renal trauma or immunopathology activates the formation of tissue kallikrein in the human kidney (2). It has been strongly suggested that beneficial cardiovascular and renal effects of angiotensin-converting enzyme inhibitors are based partly on the potentiation of endogenous kinins (3,4). Two types of receptors, i.e., B1 and B2, belonging to the superfamily of G protein-coupled receptors, have been pro- posed to mediate tissue effects of kinins (5). This classification Received May 12. 1997. Accepted October 13, 1997. Correspondence to Dr. Dimcho R. Bachvarov. Centre de recherche, L’H#{244}tel- Dieu de Qu#{233}bec. 1 1 C#{244}te-du-Palais, Qu#{233}bec (Qu#{233}bec), Canada GIR 2J6. 1046-6673/0904-0598$03.O()/() Journal of the American Society of Nephrobogy Copyright © 1998 by the American Society of Nephrology is now supported by molecular biology findings. The B2 type of receptor is optimally stimulated by the full sequence of BK or Lys-BK. B2R mediate most, if not all, of the in vivo effects usually assigned to kinins in normal rodents, rabbits, and humans. The type receptors are selectively sensitive to fragments of kinins without the C-terminal arginine (e.g., des- Arg9-BK and Lys-des-Arg9-BK, also called des-Arg’#{176}-kalli- din). Both types of kinin receptors are also identified by specific antagonists (5). R are of special interest because of their apparent upregulation after some types of tissue injury. A large body of evidence showing that the B1R are generally absent from normal tissues and animals, but are rapidly in- duced after some types of injuries under the effect of cytokines and growth factors (6), has preceded molecular genetic ap- proaches that have lately confirmed this upregulation: Tran- scriptional stimulation by interleukin-l in human fibroblasts (7,8) and in organs from rabbits pretreated by endotoxin (9) has been observed. Yet, it is not excluded that R may be eon- stitutive in some organs, e.g. , the human kidney (10). Studies on the genomie structure of the human R gene performed in our laboratory (8) enabled us to start searching for polymorphic markers in this gene that are necessary to elucidate the potential role of hereditary dysfunction of R for