title: Association of Interleukin-10 gene promoter polymorphisms with obstructive sleep apnea.
abstract: BACKGROUND
  Interleukin-10 (IL) is an anti-inflammatory cytokine that regulates normal sleep patterns, and recent studies have reported that it is a potential useful biomarker to identify presence and severity of sleep apnea syndrome (OSAS). Promoter polymorphisms of IL-10 gene have been associated with altered expression levels, which contributes to OSAS.
  
  
  OBJECTIVE
  The aim of this study was to determine the prevalence of -1082 G/A, -819 C/T, and -592 C/A promoter polymorphisms of IL-10 gene in individuals with OSAS and controls.
  
  
  METHODS
  An open-label study was performed in the Otorhinolaryngology and Sleep Disorders Outpatient Clinics. One hundred four cases with OSAS were included as the study group, and 78 individuals without OSAS were included as the controls. DNAs were extracted from peripheral blood leukocytes, and the sites that encompassed those polymorphisms were identified by DNA sequencing analyses. Data were analyzed with SNPStats and multifactor dimensionality reduction (MDR) software.
  
  
  RESULTS
  The prevalence of OSAS was higher in males in the study group when compared to controls (P = 0.0003). The IL-10-1082 G/A, -819 C/T, and -592 C/A SNPs, and their minor alleles were associated with a significantly increased risk for OSAS compared to the controls (P ˂ 0.05 for all). Furthermore, ATA haplotype frequency was significantly higher in the study group compared to the control group, but the GCC haplotype frequency was lower (P = 0.0001 and P = 0.0001). As indicated in MDR analysis, combinations of IL-10 gene were associated with OSAS in single-, double-, and triple-locus analyses.
  
  
  CONCLUSIONS
  The prevalences of the IL-10 gene promoter polymorphisms were different in OSAS patients and the controls in Turkish population. IL-10 gene polymorphisms may lead to altered inflammatory cascade, which might contribute to OSAS. Further studies on larger cohorts are needed to validate our findings.
authors.affiliation: Faculty of Science, Department of Biology, Hacettepe University, Beytepe Campus, 06800, Ankara, Turkey. s_unurlu@yahoo.com.
authors.forename: Sibel
authors.initials: S
authors.lastname: Özdaş
authors.affiliation: Otolaryngology Clinic, Yenimahalle Education and Research Hospital, Ankara, Turkey.
authors.forename: Talih
authors.initials: T
authors.lastname: Özdaş
authors.affiliation: Yunus Emre Hospital, Otolaryngology Clinic, Eskişehir, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Acar
authors.affiliation: Medical Faculty, Department of Otolaryngology, Başkent University, Ankara, Turkey.
authors.forename: Selim S
authors.initials: SS
authors.lastname: Erbek
authors.affiliation: Ankara Numune Education and Research Hospital, 2. Otolaryngology Clinic, Ankara, Turkey.
authors.forename: Sabri
authors.initials: S
authors.lastname: Köseoğlu
authors.affiliation: Ankara Numune Education and Research Hospital, 2. Otolaryngology Clinic, Ankara, Turkey.
authors.forename: Gökhan
authors.initials: G
authors.lastname: Göktürk
authors.affiliation: Faculty of Science, Department of Biology, Hacettepe University, Beytepe Campus, 06800, Ankara, Turkey.
authors.forename: Afife
authors.initials: A
authors.lastname: Izbirak
mesh_terms: D003430:Cross-Sectional Studies; D015870:Gene Expression / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics; D016753:Interleukin-10 / Q000235:genetics*; D058011:Multifactor Dimensionality Reduction; D011110:Polymorphism, Genetic / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012016:Reference Values; D017422:Sequence Analysis, DNA; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000235:genetics*
chemical_list: D005819:Genetic Markers; D016753:Interleukin-10
keywords: DNA sequencing analysis; IL-10 gene; Multifactor dimensionality reduction; Obstructive sleep apnea syndrome; Pathogenesis; Polymorphism