title: Heritability of OSA in a Rural Population.
abstract: BACKGROUND
  OSA has a familial aggregation pattern indicating that it can be partially caused by a genetic component. However, the heritability of OSA has been estimated based on the study of families of obese probands of urban populations with established OSA diagnosis. The objective of this genetic-epidemiologic study is to study families ascertained from a general rural population to determine an unbiased estimate of OSA heritability.
  
  
  METHODS
  We studied a sample of families living in Baependi, a small rural southeastern Brazilian city. Participants were assessed for anthropometric measurements, physical examination, Epworth Sleepiness Scale, blood samples for glucose and cholesterol determination, and overnight home portable monitoring.
  
  
  RESULTS
  We studied 587 participants (399 women) from 91 families, with a median (interquartile range [IQR]) of 4 (2-8) participants per family. The median age of the population was 44 years (IQR, 29-55 years) and median BMI was 25.0 kg/m(2) (IQR, 22.1-28.6 kg/m(2)). OSA, defined by apnea-hypopnea index (AHI) > 5/h, was diagnosed in 18.6% of the sample. Two polygenic models, model I (no covariate effects) and model II (with covariate effects), were fitted to the data in all analyses. Heritability estimates for AHI were 0.23 and 0.25 for model I and II, respectively. Covariates (age, sex, and BMI) showed no significant effects on the heritability estimate for AHI.
  
  
  CONCLUSIONS
  The heritability of AHI in a rural population with low levels of obesity is intermediate (25%).
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Lilian K G
authors.initials: LK
authors.lastname: de Paula
authors.affiliation: Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Rafael O
authors.initials: RO
authors.lastname: Alvim
authors.affiliation: Hospital Metropolitano Sul Dom Hélder Câmara - IMIP Hospitalar, Cabo de Santo Agostinho, Pernambuco, Brazil.
authors.forename: Rodrigo P
authors.initials: RP
authors.lastname: Pedrosa
authors.affiliation: Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Andrea R V R
authors.initials: AR
authors.lastname: Horimoto
authors.affiliation: Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: José E
authors.initials: JE
authors.lastname: Krieger
authors.affiliation: Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Camila M
authors.initials: CM
authors.lastname: Oliveira
authors.affiliation: Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Alexandre C
authors.initials: AC
authors.lastname: Pereira
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil. Electronic address: geraldo.lorenzi@gmail.com.
authors.forename: Geraldo
authors.initials: G
authors.lastname: Lorenzi-Filho
mesh_terms: D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D001938:Brazil; D005260:Female; D006801:Humans; D040582:Inheritance Patterns; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012423:Rural Health / Q000706:statistics & numerical data*; D012737:Sex Factors; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*
keywords: OSA, families; heritability; rural population