title: Family aggregation of upper airway soft tissue structures in normal subjects and patients with sleep apnea.
abstract: BACKGROUND
  Sleep apnea is believed to be a genetic disorder. Thus, we hypothesized that anatomic risk factors for sleep apnea would demonstrate family aggregation.
  
  
  OBJECTIVE
  We used volumetric magnetic resonance imaging in a sib pair "quad" design to study the family aggregation of the size of upper airway soft tissue structures that are associated with increased risk for obstructive sleep apnea.
  
  
  METHODS
  We examined 55 sleep apnea probands (apnea-hypopnea index [AHI]: 43.2 +/- 26.3 events/h), 55 proband siblings (AHI: 11.8 +/- 16.6 events/h), 55 control subjects (AHI: 2.1 +/- 1.7 events/h), and 55 control siblings (AHI: 4.2 +/- 4.0 events/h). The study design used exact matching on ethnicity and sex, frequency matching on age, and statistical control for visceral neck fat and craniofacial dimensions.
  
  
  RESULTS
  The data support our a priori hypothesis that the volume of the important upper airway soft tissue structures is heritable. The volume of the lateral pharyngeal walls (h(2) = 36.8%; p = 0.001), tongue (h(2) = 36.5%; p = 0.0001), and total soft tissue (h(2) = 37.5%; p = 0.0001) demonstrated significant levels of heritability after adjusting for sex, ethnicity, age, visceral neck fat, and craniofacial dimensions. In addition, our data indicate that heritability of the upper airway soft tissue structures is found in normal subjects and patients with apnea. Thus, it is not simply a consequence of the prevalence of apnea.
  
  
  CONCLUSIONS
  This is the first time family aggregation of size of the upper airway soft tissue structures has been demonstrated.
authors.affiliation: Center for Sleep and Respiratory Neurobiology, 893 Maloney Building, University of Pennsylvania Medical Center, 3600 Spruce Street, Philadelphia, PA 19104-4283, USA. rschwab@mail.med.upenn.edu
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Schwab
authors.forename: Michael
authors.initials: M
authors.lastname: Pasirstein
authors.forename: Laura
authors.initials: L
authors.lastname: Kaplan
authors.forename: Robert
authors.initials: R
authors.lastname: Pierson
authors.forename: Adonna
authors.initials: A
authors.lastname: Mackley
authors.forename: Robert
authors.initials: R
authors.lastname: Hachadoorian
authors.forename: Raanan
authors.initials: R
authors.lastname: Arens
authors.forename: Greg
authors.initials: G
authors.lastname: Maislin
authors.forename: Allan I
authors.initials: AI
authors.lastname: Pack
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010160:Palate, Soft / Q000473:pathology*; D010614:Pharynx / Q000473:pathology*; D012891:Sleep Apnea Syndromes / Q000235:genetics* / Q000473:pathology*; D014059:Tongue / Q000473:pathology*