title: Bladder neck mobility is a heritable trait.
abstract: OBJECTIVE
  Congenital connective tissue dysfunction may partly be responsible for female pelvic organ prolapse and urinary incontinence. We undertook a heritability study to determine whether mobility of the bladder neck, one of the main determinants of stress urinary incontinence, is genetically influenced.
  
  
  METHODS
  Heritability study using a twin model and structural equation modelling.
  
  
  METHODS
  Queensland Institute of Medical Research, Brisbane, Australia.
  
  
  METHODS
  One hundred and seventy-eight nulliparous Caucasian female twins and their sisters (46 monozygotic pairs, 24 dizygotic pairs and 38 sisters) aged 18-24 years.
  
  
  METHODS
  We performed translabial ultrasound, supine and after bladder emptying, for pelvic organ mobility. Urethral rotation and bladder neck descent were calculated using the best of three effective Valsalva manoeuvres.
  
  
  METHODS
  Bladder and urethral mobility on Valsalva assessed by urethral rotation, vertical and oblique bladder neck descent.
  
  
  RESULTS
  Genetic modelling indicated that additive genes accounted for up to 59% of the variance for bladder neck descent. All remaining variance appeared due to environmental influences unique to the individual, including measurement error.
  
  
  CONCLUSIONS
  A significant genetic contribution to the phenotype of bladder neck mobility appears likely.
authors.affiliation: University of Sydney, NSW 2751, Australia.
authors.forename: H P
authors.initials: HP
authors.lastname: Dietz
authors.forename: N K
authors.initials: NK
authors.lastname: Hansell
authors.forename: M E
authors.initials: ME
authors.lastname: Grace
authors.forename: A M
authors.initials: AM
authors.lastname: Eldridge
authors.forename: B
authors.initials: B
authors.lastname: Clarke
authors.forename: N G
authors.initials: NG
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D004777:Environment; D005260:Female; D040941:Heredity / Q000502:physiology*; D006801:Humans; D009068:Movement / Q000502:physiology*; D017773:Pelvic Floor; D010641:Phenotype; D011391:Prolapse; D014463:Ultrasonography; D014521:Urethra / Q000000981:diagnostic imaging / Q000502:physiology*; D001743:Urinary Bladder / Q000000981:diagnostic imaging / Q000502:physiology*; D014549:Urinary Incontinence / Q000235:genetics; D014636:Valsalva Maneuver / Q000235:genetics