Braz. j. . vol.83 número6

(1)

www.bjorl.org

Brazilian

Journal

of

OTORHINOLARYNGOLOGY

REVIEW

ARTICLE

Polymorphisms

in

chronic

rhinosinusitis

with

nasal

polyps

---

a

systematic

review

夽

Vanessa

Ramos

Pires

Dinarte

a

_,

_Anemari

_Ramos

_Dinarte

_dos

_Santos

b

_,

Luiza

Ferreira

de

Araújo

c

_,

_Mariah

_Guieiro

_Alves

_dos

_Reis

d,∗

,

Edwin

Tamashiro

e

,

Fabiana

Cardoso

Pereira

Valera

e

_,

_Wilson

_Araújo

_da

_Silva

_Júnior

b,f,g,h

,

Wilma

Terezinha

Anselmo-Lima

e

a_Escola_de_Medicina_de_Marília,_Departamento_de_{Otorrinolaringologia,}_Divisão_de_{Otorrinolaringologia,}_Marília,_SP,_Brazil b_Hemocentro_de_Ribeirão_Preto,_Centro_Regional_de_Hemoterapia,_Laboratório_de_Genética_Molecular_e_{Bioinformática}_(LGMB),

RibeirãoPreto,SP,Brazil

c_Universidade_de_São_Paulo_(USP),_Faculdade_de_Medicina_de_Ribeirão_Preto,_Departamento_de_Genética,_Ribeirão_Preto,_SP,_Brazil d_Escola_de_Medicina_de_Marília,_Departamento_de_{Otorrinolaringologia,}_Marília,_SP,_Brazil

e_Universidade_de_São_Paulo_(USP),_Faculdade_de_Medicina_de_Ribeirão_Preto,_Departamento_de_{Oftalmologia,}

OtorrinolaringologiaeCirurgiadeCabec¸aePescoc¸o,RibeirãoPreto,SP,Brazil

f_Centros_de_Pesquisa,_Inovac_¸ão_e_{Difusão/Fundac}_¸ão_de_Amparo_à_Pesquisa_do_Estado_de_São_Paulo_{(Cepid/Fapesp),}_Centro_de

TerapiaCelular,DepartamentodeGenética,SãoPaulo,SP,Brazil

g_Hospital_das_Clínicas,_Universidade_de_São_Paulo_{(HCFMRP/USP),}_Faculdade_de_Medicina_de_Ribeirão_Preto,_Center_for_Medical

Genomics,RibeirãoPreto,SP,Brazil

h_Universidade_de_São_Paulo_(USP),_Lista_dos_Núcleos_de_Apoio_à_Pesquisa_(NAPs),_Center_for_Integrative_Systems_Biology_(CISBi),

SãoPaulo,SP,Brazil

Received27September2016;accepted1March2017 Availableonline23March2017

KEYWORDS

Polymorphism; Rhinosinusitis; Polyps

Abstract

Introduction:Chronicrhinosinusitiswithnasalpolypsisamultifactorialdiseasewithacomplex pathophysiologyinvolvingmultiplegeneticandenvironmentalfactors.

Objective: Thepurpose ofthiswork reviewis tofocuson theimportance ofgenetic stud-iesinchronicrhinosinusitis withnasal polypsbesidestheseveralbarriersthatexists for its understanding.

Methods:A systematicreviewonstudies ofassociationbetween singlenucleotide polymor-phismsandchronicrhinosinusitiswithnasalpolypsbasedonaPubMed/MedlineandPeriódicos

夽 _Please_cite_this_article_as:_Dinarte_VR,_Santos_AR,_Araújo_LF,_Reis_MG,_Tamashiro_E,_Valera_FC,_et_al._{Polymorphisms}_in_chronic_{rhinosinusitis}

withnasalpolyps---asystematicreview.BrazJOtorhinolaryngol.2017;83:705---11.

∗_{Corresponding}_author.

E-mail:reismariahh@gmail.com(M.G.Reis).

PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCérvico-Facial.

http://dx.doi.org/10.1016/j.bjorl.2017.03.002

(2)

CAPESsearchofallarticlespublishedbetweenJanuary2005andJanuary2015wasmade.The searchwasguidedonstudiescontainingthetermspolymorphisms,rhinosinusitis,andpolyps.

Results:Two studiesfound anassociation ofMMP-9 and MMP-2 polymorphisms andchronic rhinosinusitiswithnasalpolyps,butnotinpatientswithrecurrentnasalpolyps.Otherstudies foundanassociationofnasalpolypswithMMP-9polymorphisms,butnotwithMMP-2ones.There isevidenceofanassociationofLTC4S,NOS2A,PTGDR,MET,COX-2,OSF-2,andLFpolymorphisms andtheriskofdevelopingnasalpolyps,especiallywhencombinedwithchronicallergicrhinitis andasthma.

Conclusion:Geneticstudiesonchronicrhinosinusitiswithnasalpolypsarepromisingandmay offerinsightsintoitspathophysiology,whichislikelyaffectedbymultiplegeneticfactors. © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. This is an open access article under the CC BY license (http://

creativecommons.org/licenses/by/4.0/).

PALAVRAS-CHAVE

Polimorfismo; Rinossinusite; Pólipos

Polimorfismosnarinossinusitecrônicacompóliposnasais---umarevisãosistemática

Resumo

Introduc¸ão:A rinossinusitecrônicacompóliposnasaisé umadoenc¸a multifatorialcomuma fisiopatologiacomplexaenvolvendomúltiplosfatoresgenéticoseambientais.

Objetivo:Oobjetivodestetrabalhoéenfatizaraimportânciadosestudosgenéticosna rinossi-nusitecrônicacompóliposnasais,alémdasdiversasbarreirasexistentesparasuacompreensão.

Método: Realizou-seumarevisãosistemáticadeestudosdeassociac¸ãoentrepolimorfismosde nucleotídeo únicoerinossinusite crônicacompólipos nasais combase em umabusca feita nosbancosdedadosPubMed/MedlineePeriódicosCAPESdetodososartigospublicadosentre janeirode 2005 e janeirode 2015. A busca foi direcionadaà estudos contendo os termos polimorfismos,rinossinusiteepólipos.

Resultados: DoisestudosencontraramumaassociaçãoentreospolimorfismosMMP-9eMMP-2 erinossinusitecrônicacompólipos nasais,masnão em pacientescompólipos nasais recor-rentes.OutrosestudosencontraramumaassociaçãodepóliposnasaiscompolimorfismosMMP-9, masnãocomMMP-2.ExistemevidênciasdeumaassociaçãodospolimorfismosLTC4S,NOS2A, PTGDR,MET,COX-2,OSF-2eLFeoriscodedesenvolverpóliposnasais,especialmentequando combinadoscomrinitealérgicacrônicaeasma.

Conclusão:Estudosgenéticossobre rinossinusitecrônicacompólipos nasaissãopromissores epodem oferecer conhecimentosobresua fisiopatologia,que éprovavelmenteafetadapor múltiplosfatoresgenéticos.

creativecommons.org/licenses/by/4.0/).

Introduction

ThelastEuropeanPositionPaperonRhinosinusitisandNasal Polyps(EPOS2012)definedchronic rhinosinusitisas inflam-mationofthenoseandtheparanasalsinuses≥12weeksthat is characterizedby two or more symptoms,one of which shouldbeeither nasalblockage/congestion/obstructionor nasal discharge (anterior/posterior nasal drip) associated with facial pain/pressure or reduction/loss of smell. In children, cough should be included as a symptom. Addi-tionalsymptoms include endoscopic signs of Nasal Polyps (NP),and/ormucopurulentdischargeprimarilyfrommiddle meatus,and/oredema/mucosalobstructioninmiddle mea-tus. Computed Tomography (CT) changes includemucosal changeswithintheostiomeatalcomplexandorsinuses.1

According to a study performed within the Global AllergyandAsthmaEuropeanNetwork(GA2_LEN),_the_overall

prevalence of Chronic Rhinosinusitis (CRS) in Europe was 10.9%.2_In_São_Paulo,_Brazil,_Pilan_et_al.₍₂₀₁₂₎_found_a preva-lence of 5.51%.3 _{Additionally,} _it _was _estimated _that _CRS affects 13%of the totalpopulation in the UnitedStates.4 These figures arewithin the estimated global prevalence of the condition, which affects 5%---15% of the general population.1

The socioeconomic burden of CRS is substantial and includesnotonlymedicalcosts(doctor’svisits,exams, med-ication),butalsocoststothesocietyandeconomy,including highmorbidity,workabsenteeism,andpooracademic per-formance(Fig.1).

(3)

Database search (2005–2015): 30 studies

identified

Inclusion and exclusion

criteria 24 studies excluded

6 studies selected

Figure1 Databasesearchandselectionofstudies.

Someguidelineshavealsoadvisedfurthercategorization of patient groups with CRSwNP into allergic fungal rhi-nosinusitis,Aspirin-ExacerbatedRespiratoryDisease(AERD), and/orCysticFibrosis(CF).6_In_fact,_further_{categorization} or subanalysis of cases into subphenotypes or endotypes couldhelpidentifythedifferentpathophysiological mecha-nismsofCRSandimprovetreatment.

CRSwNP is a complex, multifactorial disease that involves multiple genetic, immunological, environmental, and mucosal factors, but its etiology remains unclear. Many potential contributing factors have been identified, including allergic responses, impaired mucociliary clear-ance, immune dysfunction, impaired epithelial defense, microbes,andenvironmentalexposure.7_{Nevertheless,} fur-ther research is needed todetermine therole of genetic factorsandtheirinteractionwiththesecontributingfactors inthepathophysiologyofCRSwNP.

The lack of suitable animal models, the difficulty in standardizingphenotypes,theneed forlargecase---control cohorts,andthehighcostsandsparsereplicationofstudies arethemainhurdlestoelucidatingthepathophysiologyof CRSwNP.

There isstrong evidencefor theimplicationof genetic factorsinthepathophysiologyofCRSwNP.TheCysticFibrosis TransmembraneConductanceRegulator(CFTR)gene,whose mutationsresultinCysticFibrosis(CF),hasbeen themost replicatedgeneassociatedwithCRS.Thereisahigh preva-lence of CRSwNP in CF carriers, but some studies have

suggestedthat CTFRmutations alsooccurin CRS patients withoutCF.8

Family studies indicate the existence of a hereditary factor in the pathogenesis of CRSwNP, but environmental factorsalsoplayasignificantroleintheoccurrenceofnasal polyps. For instance, studies of identical twins have not shownthatbothsiblingsalwaysdeveloppolyps.1

Methods

WeconductedaPubMed/MedlineandPeriodicCAPESsearch ofallEnglish-language articlespublishedbetweenJanuary 2005 and January 2015 with the search terms poly-morphisms, rhinosinusitis, and polyps. Studies that only evaluatedpatientswithaspirin-exacerbatedrespiratory dis-ease,cysticfibrosis,Epstein---Barrvirus,asthmaandstudies thatgroupedtogetherCRSpatientswithandwithoutnasal polypswereexcluded.Studiesthatonlyevaluatedpatients withCRSwNPwereincluded.

Ofthe30studiesidentified,sixcase---controlstudiesmet theinclusionandexclusioncriteriaandwereincludedinthis review.

Results

Inastudy conductedin Taiwan, Wangetal.(2008) inves-tigatedthe roleof 17 MatrixMetalloproteinase-2 (MMP-2) Single Nucleotide Polymorphisms (SNPs) in the develop-mentofCRSwNPusingthreemodelsofgeneticinheritance. Matrix Metalloproteinases (MMPs) are a family of zinc-and calcium-dependent endopeptidases that are impor-tant in upper airway remodeling. MMP-2 cleaves type IV collagen,themajorstructurecomponentofbasement mem-branes. The authors recruited 136 patients with CRSwNP and136 control subjects withchronic hypertrophic rhini-tis who underwent turbinectomy (Table 1). Of the 17 polymorphisms investigated, only rs857403 was associ-atedwithCRSwNP (p=0.03). However,the resultbecame non-significant after includingan additional 691 controls, indicatingthat the initialsignificance wasafalse-positive finding. The study also grouped the 17 SNPs into four haplotypeblocks,buthaplotypeanalysisdidnotyield sig-nificantresultsforanyblock(Table2).Thus,the17MMP-2 polymorphismswerenotsignificantlyassociatedwithnasal polyps.9

Inanothercase---controlstudy,Wangetal.(2010) inves-tigatedtheassociationbetweenMPP-9genepolymorphisms andthepresenceofnasalpolypsinpatientswithCRSwNP. In total, 203 patients with CRSwNP and 730 controls recruitedfromthe generalpopulationwereenrolled.One

Table1 BaselinecharacteristicsofstudysubjectsinastudythatinvestigatedtherelationshipbetweenMMP-2gene polymor-phismsandtheriskofnasalpolyps(NP).

N RecurrentNP Non-recurrentNP Meanageyears Men/women

Cases 136 26 110 42.5 96/40

Controls 136 --- --- 34.9 108/28

MMP,matrixmetalloproteinase.

(4)

Table2 Haplotypeanalysisofthefour haplotypeblocks formedby17MMP-2polymorphisms.

Block1 Block2 Block3 Block4

p-Value 0.26 0.58 0.44 0.53

MMP,matrixmetalloproteinase.

Source:AdaptedfromWangetal.(2008).9

functional promoter SNP (rs3918242) and three linked SNPs(rs2274756,rs3787268,andrs2664538)wereselected and genetic effects were evaluated using three models of inheritance. The results showed that three SNPs were associatedwiththedevelopmentofnasalpolyps.TheMPP-9 promoter SNP (rs3918242, i.e., −1562 C/T) yielded the mostsignificantresult(Table3).However,noneofthefour SNPs were associated with CRSwNP in recurrent patients (p=ns).Haplotypeanalysis,includingthefourSNPs,showed a positive association for haplotype TGGA (p=0.00045). Thus, the authors concluded that MPP-9 polymorphisms mayincrease therisk ofdeveloping CRSwNP,but maynot beassociatedwithitsreccurrence.10

In a more recent study, Wang et al. (2013) eval-uated the expression of MMP-2 and MMP-9 promoter polymorphismsbyimmunohistochemistry andtheir associ-ation with CRSwNP (Table 4). The hypothesis that MMPs are involved with NP formation is based on the role of MMPs in asthma and on the fact that asthma and nasal polypsshare similar presentationand histopathology find-ings. The authors recruited 30 patients with bilateral CRSwNP and no NP recurrence at 6 month follow-up and 32 patients who underwent revision surgery for NP. The controlgroup consisted of 31 patients with chronic rhini-tis and septum deviation. Two functional promoter SNPs were selected, one in the MMP-9 gene (rs3918242, i.e., −1562 C/T) and the other in the MMP-2gene (rs243865, i.e.,−1306 A/G). Even though MMP-9 andMMP-2 expres-sionwassignificantlyhigherinpatientswithrecurrentand non-recurrent NP than in controls, no significant differ-enceswereobservedbetweenrecurrentandnon-recurrent patients.The authorsconcluded that thepathogenesis of recurrentnasalpolypsmayinvolvemechanismsotherthan MMPs.11

BenitoPescadoretal.(2012)conductedacase---control study in Spain with241 patients with CRSwNP (with and without asthma) and 245 controls to determine whether polymorphisms in genes implicated in inflammatory

pathways (Leukotriene C4 Synthase [LTC4S], Cysteinyl Leukotriene Receptor 1 [CYSLTR1], Prostaglandin D2 Receptor [PTGDR], and Nitric Oxide Synthase[NOS2]) are associatedwithNP.Theauthorsfoundnosignificant associa-tionbetweensimpleNPandtheSNPsevaluated.However,a significantassociationwasobservedbetweenNPandspecific phenotypes(atopy,asthma,NonsteroidalAnti-Inflammatory Drug intolerance [NSAIDi],and aspirin triad). Specifically, significant associationswerefoundin the−444A>CLTC4S polymorphism in patients with NP and atopy (p=0.033) andNPandatopicasthma(p=0.012);andwhentheCCTTT nucleotide repeat in the NOS2A gene was present >14× in patientswithNPandasthma (p=0.034), NPandNSAIDi (p=0.009),andtheaspirintriad(p=0.005).Additionally,the PTGDRdiplotype(CCCT/CCC)wasmorefrequentinpatients withNP(p=0.043),NPandasthma(p=0.013),andwiththe aspirin triad (p=0.041) (Table 5). The authors concluded that nasal polyposis was associated with specific poly-morphisms only when combinedwith the aforementioned phenotypes.12

TheassociationofNPwithallergyandasthma wasalso evaluatedinaPolishpopulationbySitareketal.(2012).13 The study investigated the association of the −765 G/C polymorphism ofcyclooxygenase-2(COX-2) gene(rs20417) andthe−14C/Gpolymorphismoftransmembranetyrosine kinase receptor (MET) gene (rs78116323) with the risk to develop CRSwNP. The authors recruited195 patients with NP, 63 of whom had chronic allergic rhinitis and 65 had asthma,and200controlswithhearinglosscomplaintsand nonasalpathologies.Theauthorsfoundastrongassociation betweenthepolymorphismsevaluatedandanincreasedrisk ofdevelopingNPinthePolishpopulation,eveninpatients without asthma or allergy(Table6).Inaddition,a signifi-cantassociationwasalsoobservedforthe−765G/CCOX-2 polymorphisminpatientswithasthmaorallergy(Table6). The authorsconcludedthatCOX-2andMETgene polymor-phisms may play a significant role in the development of CRSwNP,whichmayalsodependonthepresenceofasthma orallergy.13

ThesamePolishresearchgroupalsoevaluatedthe asso-ciationofthe−33C/GpolymorphismofOsteoblastSpecific Factor-2 (OSF-2) gene and the 140 A/G polymorphism of Lactoferrin(LF)genewithNPinthesamepatientcohortas inSitareketal.(2012).13_The_authors_reported_that_the₁₄₀ A/GLF,and−33C/Gand−33G/GOSF-2genotypes,were associated withan increasedrisk of developing NP in the studypopulation.Inaddition,theassociationofthe−33G/G homozygoteandthe140A/Gheterozygotewithanincreased

Table3 MMP-9polymorphisms,underthreegeneticmodels,andtheirrelationshipswithnasalpolyposis.

p-Value

SNP(singlenucleotidepolymorphisms) Dominant Additive Recessive

rs2664538(exon6) 0.64 0.752 0.073

rs3787268 0.503 0.345 0.361

rs2274756(exon12) 0.034 0.02 0.134

rs3918242 0.023 0.012 0.097

MMP,Matrixmetalloproteinase.

(5)

Table4 ExpressionofMMP-9andMMP-2polymorphismsbyimmunohistochemistryinchronicrhinosinusitiswithnasalpolyps (CRSwNP)patientswithrecurrentandnon-recurrentNP.

RecurrentNP Non-recurrentNP Controls

ElevatedMMP-9(MMPpolymorphism)expression Yes Yes No

ElevatedMMP-2(MMP-2polymorphism)expression Yes No No

NP,nasalpolyps;MMP,matrixmetalloproteinase. Source:AdaptedfromWangetal.(2013).11

Table5 Associationbetween LTC4S,NOS2A,andPTGDRgenepolymorphismsandnasalpolyps(NP),NP andatopy,NP and asthma,aspirintriad,andnonsteroidalanti-inflammatorydrugintolerance(NSAIDi).

NP NP+atopy NP+asthma Aspirintriad NSAIDi

−444A>CLTC4S +(p=0.033) +(p=0.012)

NOS2AVNTR:CCTTT(>14×) +(p=0.034) +(p=0.005) +(p=0.009)

PTGDRCCCT/CCCC +(p=0.043) +(p=0.013) +(p=0.041)

LTC4S,leukotrieneC4synthase;NOS2A,nitricoxidesynthase;VNTR,variablenumbertandemrepeat;PTGDR,prostaglandinD2receptor. Source:AdaptedfromBenitoPescadoretal.(2012).12

Table6 Oddsratio(OR)and95%confidenceintervals(CI)fortheassociationbetweenCOX-2andMETgenepolymorphismsand nasalpolyps(NP)phenotypeswithandwithoutallergyorasthma.

−765G/CCOX-2 −14C/GMET

OR(95%CI) p-Value OR(95%CI) p-Value

NP(nasalpolyps) 7.79(4.88---12.4) <0.001 2.83(1.74---4.61) <0.001

Allergy 5.64(2.91---10.9) <0.001

Asthma 4.74(2.49---9.03) <0.001

Withoutallergy 7.25(4.38---12.1) <0.001 2.47(1.46---4.17) <0.001

Withoutasthma 7.61(4.47---12.6) <0.001 2.59(1.54---4.37) <0.001

COX-2,cyclooxygenase-2;MET,tyrosinekinasereceptor. Source:AdaptedfromSitareketal.(2012).13

Table7 Oddsratio(OR)and95%confidenceintervals(CI)fortheassociationsbetweenOSF-2(−33C/Gand−33G/G)andLF

polymorphismsandNPphenotypeswithandwithoutallergyorasthma.

−33C/GOSF-2 −33G/GOSF-2 140A/GLF

OR(95%CI) p-Value OR(95%CI) p-Value OR(95%CI) p-Value

NP 3.48

(2.19---5.52)

<0.001 16.45

(6.71---40.3)

<0.001 4.78

(3.07---7.24)

<0.001

Allergy 2.4

(1.23---4.69)

0.014 16.01

(5.77---44.41)

<0.001 3.22

(1.74---6.11)

<0.001

Asthma 2.4

(1.23---4.69)

0.014 17.9

(6.53---49.05)

<0.001 3.25

(1.75---6.04)

<0.001

Withoutallergy 3.72

(2.24---6.19)

<0.001 3.73

(2.24---6.19)

<0.001 3.89

(2.4---6.31)

<0.001

Withoutasthma 15.11

(5.91---38.6)

<0.001 14.07

(5.47---36.16)

<0.001 3.62

(2.45---5.34)

<0.001

(6)

riskof NPwasstrongerin patientswithallergyor asthma thanin patientswithout theseconditions (Table7).Thus, theLFandOSF-2genepolymorphismswereassociatedwith anincreasedriskofdevelopingNPandtheassociationmay alsodependonthepresenceofasthmaandchronicallergic rhinitis.14

Discussion

Mostgeneticstudies of CRSwNP have focused onthe role ofinnateimmunityinthepathophysiologyofCRS.1_Most_of thesestudies are candidategene studies, which compare theallelefrequencies of SingleNucleotidePolymorphisms (SNPs) within genes that are suspected a priori of being involvedwiththediseaseamongpatientswithCRSand con-trols.However,associationstudiesusuallyhaveinadequate power, mostly due to highly heterogeneousstudy groups, andlimitedabilitytogeneratenovelinformation,once can-didategenesareselectedbasedonwhatissuspectedabout thedisease.7_Conversely,_Genome-Wide_Association_Studies (GWAS) use a hypothesis-independent approach to exam-ine a number of polymorphisms across the entire human genome. However, GWAS of CRS are still lacking due to the high costs and large patient cohorts required.6 _DNA pool-basedGWAS(pGWAS)thatreplaceindividualDNA geno-typingbypooledgenomicDNAareanalternativetoreduce costs.1

Intheir 2008study,Wangetal.failedtofindevidence for aroleof MMP-2genepolymorphisms inthe riskof NP inasmallpatientcohort.In2010,thesameresearchgroup showedthatMMP-9genepolymorphismsaffected the sus-ceptibilityofdevelopingNPinaChinesepopulation.Inthat study,thesample size wasmoderately adequate,but the three-monthfollow-upforNPrecurrencewasshort.Another limitationisthatcontrolsdidnotreceivefullnasal exami-nationtoruleoutNP.

InastudyevaluatingtheexpressionofMMP-2and MMP-9 in recurrent NP, Wang et al. (2013) showed that even thoughMMP-9andMMP-2expressionwassignificantlyhigher inpatientswithrecurrentandnon-recurrentNPthanin con-trols,nosignificantdifferenceswereobservedbetweenthe twoNP presentations. The authors suggested that mech-anismsother than MMPs maybe involved inrecurrent NP. Themainlimitationofthatstudywasthesmallsamplesize (patientsandcontrols), which couldnotexcludea typeII error.Thesix-monthfollow-upwasanothershortcomingof thatstudy,becauseNPmayrecurseveralyearsaftersurgery. Lastly,theauthorsrecognizedthatusingcontrolswithnasal pathologies(patientswithchronicrhinitisandseptum devi-ationwhounderwentrevisionsurgery)wasinadequate.

ThestudyconductedbyBenitoPescadoretal.(2012)in SpainexaminedpolymorphismswithintheLTC4S,CYSLTR1, PTGDR,andNOS2AgenesandtheirassociationwithNP.The authorsconcludedthatspecific polymorphismswere asso-ciated withthe development of NP when combined with allergyandasthmaphenotypes.

Theassociation ofNP,allergy,andasthma withspecific genepolymorphismswasalsoinvestigatedbySitareketal. (2012)in a Polishpopulation. The authorsfound that the −14 C/G MET and −765 G/C COX-2 polymorphisms are

associated withan increasedrisk of developing NP, which mayalsodependonthepresenceofallergyandasthma.

ThesamePolishresearchgroup14 _found_a_positive asso-ciation between the −33 C/G OSF-2 and 140 A/G LF polymorphismsandNP, andtheassociation wasalsolikely dependentonthepresenceofallergyandasthma.

Geneticstudiesarepromisingandmayofferinsightsinto the pathophysiology of CRS, but several factors may be responsiblefor theassociationsandshouldbeconsidered. Phenotyping of patients andcontrols must beaccurateto avoid comparisons of heterogeneous groups. Sample sizes mustbelargeenoughtoreducethepossibilitythatrandom associations are found between SNPs and CRS. Moreover, environmental factors that interact withthe genome and helptriggerdiseaseshouldalsobeinvestigated.15_The iden-tified SNPmay not directly cause disease, but may be in linkagedisequilibrium(LD)withtheactual causalvariant. Alternatively, the associated SNP may be an expression quantitativetraitlocus(eQTL)affectingthetranscriptionof anothergeneinvolvedinthedisease.7_Thus,_the_replication ofstudiesreducesthepossibilityofrandomassociations.

Todate,CFTRhasbeenthemostreplicatedgene associ-atedwithCRS,butSNPsinIL1A,TNF(tumornecrosisfactor), and AOAH (acyloxyacyl hydrolase) genes have also been replicated. Several other polymorphisms associated with CRS have been published, but have notbeen replicated,1 including Human Leukocyte Antigen (HLA) alleles, espe-ciallyHLA-DRB1*04,genesofinnateimmunity(e.g.,IRAK4, nitric oxide synthase --- NOS, MET proto-oncogene, SER-PINA1),inflammatorymediators(e.g.,IL13,IL33,IL22RA1), andgenesinvolvedinarachidonicacidmetabolismand tis-sueremodeling(metalloproteinaseMMP9,TGFB1).7

Conclusion

Genetic studies of CRSwNP are promising and may offer insights into the pathophysiology of the disease,which is likely affected by multiple genetic factors. Nevertheless, thereareseveral barrierstounderstanding the pathophy-siologyofCRSwNP,includingthevariabilityinphenotyping, lackofcohortstudies,limitedresearchfunding,andlackof aclearunderstandingofhowgeneticandepigeneticchanges maytriggerthedisease.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

References

1.FokkensWJ,LundVJ,MullolJ,BachertC,AlobidI,BaroodyF, etal.Europeanpositionpaperonrhinosinusitisandnasalpolyps 2012.Rhinology2012Suppl.2012;23:1---298.

2.Hastan D, Fokkens WJ, Bachert C, Newson RB, Bislimovska J, Bockelbrink A, et al. Chronic rhinosinusitis in Europe --- an underestimated disease. A GA(2) LEN study. Allergy. 2011;66:1216---23.

(7)

4.PleisJR, Ward BW, Lucas JW. Summary health statisticsfor U.S.adults:NationalHealthInterviewSurvey,2009.VitalHealth Stat.2010;249:1---207.

5.Anselmo-LimaWT,SakanobE, TamashiroE,Nunes AAA, Fer-nandes AM, Pereira EA, et al. Rhinosinusitis: evidence and experience.Asummary.BrazJOtorhinolaryngol.2015;81:8---18. 6.BachertC,PawankarR,ZhangL,BunnagC,FokkensWJ, Hami-los DL. ICON: chronic rhinosinusitis. World Allergy OrganJ. 2014:7---25.

7.HsuJ,AvilaPC,Kern RC,HayesMG,SchleimerRP,PintoJM. Geneticsofchronicrhinosinusitis:stateofthefieldand direc-tionsforward.JAllergyClinImmunol.2013;131:977---93. 8.WangX,KimJ,McWilliamsR,CuttingGR.Increasedprevalence

ofchronicrhinosinusitisincarriersofacysticfibrosismutation. ArchOtolaryngolHeadNeckSurg.2005;131:237---40.

9.Wang LF, Chien CY, Kuo WR, Tai CF, Juo SH. Matrix metalloproteinase-2genepolymorphismsinnasalpolyps.Arch OtolaryngolHeadNeckSurg.2008;134:852---6.

10.Wang LF, Chien CY, Tai CF, Kuo WR, Hsi E, Juo SH. Matrix metalloproteinase-9genepolymrphismsinnasalpolyposis.BMC MedGenetics.2010;11:85.

11.Wang LF,ChienCY, ChiangFY,Chai CY,Tai CF.Expressionof matrixmetalloproteinase-2andmatrixmetalloproteinase-9in recurrentchronicrhinosinusitiswithnasalpolyposis.Kaohsiung JMedSci.2013;29:26---31.

12.BenitoPescadorD,Isidoro-GarcíaM,García-SolaesaV,Pascual de PedroM, SanzC,Hernández-HernandézL, et al.Genetic association study in nasal polyposis. J Investig Allergol Clin Immunol.2012;22:331---40.

13.SitarekP,Zielinska-BlizniewskaH,DzikiL,MilonskiJ, Przyby-lowskaK,MuchaB,etal.Associationofthe−14C/GMETand

the−765G/CCOX-2genepolymorphismswiththeriskofchronic rhinosinusitiswithnasalpolypsinaPolishpopulation.DNACell Biol.2012;31:1258---66.

14.Zielinska-BlizniewskaH,SitarekP,MilonskiJ,DzikiL, Przyby-lowskaK,OlszewskiJ,etal.Associationofthe−33C/GOSF-2

andthe140A/GLFgenepolymorphismswiththeriskofchronic rhinosinusitiswithnasalpolypsinaPolishpopulation.MolBiol Rep.2012;39:5449---57.