Delivered by Publishing Technology to: Martin Desrosiers IP: 173.177.149.189 On: Sun, 18 Apr 2010 15:10:56 Copyright (c) Oceanside Publications, Inc. All rights reserved. For permission to copy go to www.copyright.com Polymorphisms in the SERPINA1 (Alpha-1-Antitrypsin) gene are associated with severe chronic rhinosinusitis unresponsive to medical therapy Shaun J. Kilty, M.D., 1 Yohan Bosse ´, Ph.D., 2,3 Chantale Cormier, M.D., 1 Leandra Mfuna Endam, M.Sc., 1 and Martin Y. Desrosiers, M.D. 1,4 ABSTRACT Background: Alpha-1-antitrypsin (AAT) is a serine protease inhibitor that blocks the protease, neutrophil elastase. Previous population studies have suggested that heterozygote status for the AAT gene (SERPINA1) is a risk factor for chronic rhinosinusitis with nasal polyposis (CRSwNP). This implies a potential genetic predisposition to CRS tied to AAT deficiency. The purpose of this study was to investigate the association between single nucleotide polymorphisms (SNPs) in the SERPINA1 gene and CRS. Methods: DNA extracted from a population of 206 patients diagnosed with CRSwNPs and 196 postal code–matched controls was used. A maximally informative set of tagging SNPs from SERPINA1 on chromosome 14q were selected from the HapMap data set (International HapMap Consortium, Nature 437:1299 –1320, 2005) and genotyped on the Sequenom platform (Sequenom, San Diego, CA). Results: Successful genotyping was performed for 32 of 33 SNPs. Two SNPs (rs1243168 and rs4900229) located upstream of the SERPINA1gene, were associated with CRS. Individuals homozygous (TT) for these SNPs had an increased probability of having CRS with an odds ratio of 5.95 and 1.49, respectively. Subgroup analysis according to severity of disease identified each SNP to be increasingly common in individuals as disease severity increased (p  0.001). These individuals were also less likely to be responsive to medical therapy (p  0.001). Conclusion: Polymorphisms of the SERPINA1 gene are associated with clinically severe CRS. These results, from a small subset of individuals with CRS, suggest that defects in AAT may be implicated in a subset of individuals unresponsive to conventional therapy and suggests that alternate therapies may be required for their management. (Am J Rhinol Allergy 24, e4 –e9, 2010; doi: 10.2500/ajra.2010.24.3429) Key words: Alpha-1-antitrypsin, chronic rhinosinusitis, genetics, polymorphisms, protease, protease inhibitor, SERPINA1 C hronic rhinosinusitis (CRS) is one of the three most common chronic diseases in North America. CRS has a prevalence of up to 5.7% in Canada, while affecting 31 million people in the United States each year. 1,2 This illness is likely heterogeneous in etiology, with a common clinical manifestation, CRS with or without nasal polyposis (CRSwNP and CRSw/oNP). Although this population of patients may be considered to have a common phenotype of disease, there may exist a number of different genotypes for this disease. Therapy for CRS, to date, has largely focused on treating the clinical manifestations of disease, the phenotype, whereas identifying geno- typic causes may hold the promise for more specific therapies. -1-Antitrypsin (AAT) deficiency is a genetically inherited disorder of the SERPINA1 gene that occurs primarily in white populations. Its most common clinical manifestation in homozygotes is the early onset of panacinar emphysema. 3 AAT is a serpin (serine protease inhibitor), which are a critical group of proteins that regulate various inflamma- tory cascades within the body. Their role is to balance protease function with their antiprotease activity. Specifically, AAT has a major role in the neutralization of neutrophil proteases, in particular, neutrophil elastase. 4 Without adequate levels of AAT, neutrophil elastase levels will remain high. Free neutrophil elastase can be a major source of mucosal inflam- mation. AAT activity has been found to be elevated in chronic sinus- itis, reflecting its protective function, as its high affinity for elastase results in a rapid suppression of this enzyme’s proteolytic effects. 5 Stimulants that have been identified to cause the release of neutrophil elastase in CRS include specific allergens, fungi, and bacteria such as Staphylococcus aureus via a superantigen mechanism. 6–8 A patient with a known deficit of AAT may therefore have a predisposition for CRS when affected by one or more these identified stimulants. 9 Prevalence studies of specific white populations have shown that subjects diagnosed with CRSwNP are heterozygous for AAT defi- ciency type gene mutations three to five times more frequently than are controls. 10,11 Also, those subjects that are heterozygous carriers of AAT deficiency have been shown to have a moderate decrease (50– 82%) of the AAT concentration in comparison with normal gene carriers. 11 This suggests that poorly controlled neutrophil elastase activity caused by insufficient AAT may be related to sinus disease in these subjects. The purpose of our study was to investigate the association between single nucleotide polymorphisms (SNPs) in the SERPINA1 gene and CRS. METHODS We performed a genetic association study of the candidate gene, SERPINA1. This involves genotyping SNPs within a candidate gene (or genes) suspected of involvement with the disease under con- sideration either based on known biological function or its position From the 1 The Department of Otolaryngology, Ho ˆpital Ho ˆtel–Dieu de Montre ´al, Universite ´ de Montre ´al, Montreal, Quebec, Canada, 2 Centre de Recherche, Ho ˆpital Laval, Institut Universitaire de Cardiologie et de Pneumologie de l’Universite ´ Laval, Quebec City, Quebec Canada, 3 Laval University Hospital Research Center (CRCHUL), Quebec City, Quebec, Canada, and 4 Department of Otolaryngology–Head and Neck Surgery, McGill University, Montreal, Quebec, Canada Accepted for presentation at the 2008 annual meeting of the American Rhinologic Society, Chicago, IL, September 20, 2008. Supported by the Fondation Antoine Turmel, a private, nonprofit, philanthropic insti- tution Y. Bosse ´ is a research scholar from the Heart and Stroke Foundation of Canada. M. Desrosiers receives grant support from Fondation Antoine Turmel. This research was conducted with the approval of the Institutional Review Board at the Ho ˆpital Ho ˆtel-Dieu de Montreal, Centre Hospitalier de l’Universite ´ de Montre ´al (CHUM) Address correspondence to Shaun Kilty, M.D., 1354 Wellington Street W, Ottawa, Ontario K1Y 3C3, Canada E-mail address: shaunkilty@hotmail.com Address reprint requests to Martin Desrosiers, M.D., Ho ˆtel-Dieu de Montreal, 3840 St. Urban Street, Montre ´al, Quebec H2W 1T8, Canada E-mail address: desrosiers_martin@hotmail.com Copyright © 2010, OceanSide Publications, Inc., U.S.A. e4 January–February 2010, Vol. 24, No. 1 DO NOT COPY