title: Hospitalization Risk Due to Respiratory Illness Associated with Genetic Variation at IFITM3 in Patients with Influenza A(H1N1)pdm09 Infection: A Case-Control Study.
abstract: BACKGROUND
  Recent studies suggest an association between the Interferon Inducible Transmembrane 3 (IFITM3) rs12252 variant and the course of influenza infection. However, it is not clear whether the reported association relates to influenza infection severity. The aim of this study was to estimate the hospitalization risk associated with this variant in Influenza Like Illness (ILI) patients during the H1N1 pandemic influenza.
  
  
  METHODS
  A case-control genetic association study was performed, using nasopharyngeal/oropharyngeal swabs collected during the H1N1 pandemic influenza. Laboratory diagnosis of influenza infection was performed by RT-PCR, the IFITM3 rs12252 was genotyped by RFLP and tested for association with hospitalization. Conditional logistic regression was performed to calculate the confounder-adjusted odds ratio of hospitalization associated with IFITM3 rs12252.
  
  
  RESULTS
  We selected 312 ILI cases and 624 matched non-hospitalized controls. Within ILI Influenza A(H1N1)pdm09 positive patients, no statistical significant association was found between the variant and the hospitalization risk (Adjusted OR: 0.73 (95%CI: 0.33-1.50)). Regarding ILI Influenza A(H1N1)pdm09 negative patients, CT/CC genotype carriers had a higher risk of being hospitalized than patients with TT genotype (Adjusted OR: 2.54 (95%CI: 1.54-4.19)).
  
  
  CONCLUSIONS
  The IFITM3 rs12252 variant was associated with respiratory infection hospitalization but not specifically in patients infected with Influenza A(H1N1)pdm09.
authors.affiliation: Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal.
authors.forename: Vânia
authors.initials: V
authors.lastname: Gaio
authors.affiliation: Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal.
authors.forename: Baltazar
authors.initials: B
authors.lastname: Nunes
authors.affiliation: Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Pechirra
authors.affiliation: Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Conde
authors.affiliation: Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal.
authors.forename: Raquel
authors.initials: R
authors.lastname: Guiomar
authors.affiliation: Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal.
authors.forename: Carlos Matias
authors.initials: CM
authors.lastname: Dias
authors.affiliation: Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal.
authors.forename: Marta
authors.identifier: http://orcid.org/0000-0001-6464-548X
authors.initials: M
authors.lastname: Barreto
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D012150:Polymorphism, Restriction Fragment Length; D016601:RNA-Binding Proteins / Q000235:genetics*
chemical_list: C080082:IFITM3 protein, human; D008565:Membrane Proteins; D016601:RNA-Binding Proteins