title: Obstructive sleep apnoea syndrome and HLA in the North of Portugal.
abstract: BACKGROUND
  The obstructive sleep apnoea syndrome (OSAS) is a common, complex and polygenic disease with diverse aetiologies interacting to produce a single phenotype. OSAS occurs throughout the entire lifespan and familial aggregation has been suggested. Several predisposing factors, as age, gender and obesity have been described. Associations between HLA polymorphisms and sleep disorders are confirmed, in European and Non-European descendent populations. However the associations found between HLA alleles and OSAS have not been consistent and have no informative value for sleep disorder classification.
  
  
  OBJECTIVE
  To explore the genetic association of HLA with OSAS in a northern Portuguese population and to evaluate the role of obesity in the context of HLA in OSAS.
  
  
  METHODS
  A cohort of 131 patients with OSAS was studied. Patients followed up in an Outpatient Sleep Clinic were assessed by clinical history, night sleep polygraphic recording, multiple sleep latency test (when necessary for differential diagnosis), laboratorial and demographic studies. A control population (CP) of 223 healthy individuals was used for comparison. HLA-DRB1 genotyping was performed using a polymerase chain reaction with sequence specific primers methodology.
  
  
  RESULTS
  In this cohort, the HLA-DRB1*03 allele was identified as a susceptibility factor for OSAS (24% OSAS vs. 15% CP; p = 0.025; odds ratio = 1.861; 95% CI = 1.081-3.205). No significant differences were found for other HLA-DBR1* alleles.
  
  
  CONCLUSIONS
  HLA-DRB1*03 is a susceptibility factor for OSAS in Portuguese population.
authors.forename: Luís
authors.initials: L
authors.lastname: Silva
authors.forename: João
authors.initials: J
authors.lastname: Lopes
authors.forename: João
authors.initials: J
authors.lastname: Ramalheira
authors.forename: Daniela
authors.initials: D
authors.lastname: Cunha
authors.forename: Cláudia
authors.initials: C
authors.lastname: Carvalho
authors.forename: Andreia
authors.initials: A
authors.lastname: Bettencourt
authors.forename: Sandra
authors.initials: S
authors.lastname: Bras
authors.forename: Sandra
authors.initials: S
authors.lastname: Costa
authors.forename: M Berta
authors.initials: MB
authors.lastname: Silva
authors.affiliation: Hospital de Santo Antonio/Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Martins-da-Silva
mesh_terms: D015331:Cohort Studies; D005260:Female; D005805:Genes, MHC Class I; D005802:Genes, MHC Class II; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006680:HLA Antigens / Q000235:genetics*; D059811:HLA-DRB1 Chains / Q000235:genetics; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology; D010044:Outpatient Clinics, Hospital / Q000706:statistics & numerical data; D011174:Portugal / Q000453:epidemiology; D012307:Risk Factors; D012494:Sampling Studies; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*
chemical_list: D006680:HLA Antigens; D059811:HLA-DRB1 Chains