title: Familial aggregation and heritability of pyloric stenosis.
abstract: BACKGROUND
  Pyloric stenosis is the most common condition requiring surgery in the first months of life. Case reports have suggested familial aggregation, but to what extent this is caused by common environment or inheritance is unknown.
  
  
  OBJECTIVE
  To investigate familial aggregation of pyloric stenosis from monozygotic twins to fourth-generation relatives according to sex and maternal and paternal contributions and to estimate disease heritability.
  
  
  METHODS
  Population-based cohort study of 1,999,738 children born in Denmark between 1977 and 2008 and followed up for the first year of life, during which 3362 children had surgery for pyloric stenosis.
  
  
  METHODS
  Familial aggregation of pyloric stenosis, evaluated by rate ratios.
  
  
  RESULTS
  The incidence rate (per 1000 person-years) of pyloric stenosis in the first year of life was 1.8 for singletons and 3.1 for twins. The rate ratios of pyloric stenosis were 182 (95% confidence interval [CI], 70.7-467) for monozygotic twins, 29.4 (95% CI, 9.45-91.5) for dizygotic twins, 18.5 (95% CI, 13.7-25.1) for siblings, 4.99 (95% CI, 2.59-9.65) for half-siblings, 3.06 (95% CI, 2.10-4.44) for cousins, and 1.60 (95% CI, 0.51-4.99) for half-cousins. We found no difference in rate ratios for maternal and paternal relatives of children with pyloric stenosis and no difference according to sex of cohort member or sex of relative. The heritability of pyloric stenosis was 87%.
  
  
  CONCLUSIONS
  Pyloric stenosis in Danish children shows strong familial aggregation and heritability.
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, 5 Artillerivej, DK-2300 Copenhagen S, Denmark. ckr@ssi.dk
authors.forename: Camilla
authors.initials: C
authors.lastname: Krogh
authors.forename: Thea K
authors.initials: TK
authors.lastname: Fischer
authors.forename: Line
authors.initials: L
authors.lastname: Skotte
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Biggar
authors.forename: Nina
authors.initials: N
authors.lastname: Øyen
authors.forename: Axel
authors.initials: A
authors.lastname: Skytthe
authors.forename: Sanne
authors.initials: S
authors.lastname: Goertz
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
authors.forename: Jan
authors.initials: J
authors.lastname: Wohlfahrt
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
mesh_terms: D015331:Cohort Studies; D016208:Databases, Factual; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D040582:Inheritance Patterns; D008297:Male; D011707:Pyloric Stenosis / Q000453:epidemiology / Q000235:genetics*; D014430:Twins, Monozygotic