title: A timing-of-birth effect on multiple sclerosis clinical phenotype.
abstract: BACKGROUND
  A month-of-birth (MOB) effect has been shown in multiple sclerosis (MS).
  
  
  METHODS
  Our chi(2) analyses looked at whether this MOB effect differed by MS phenotype ("bout onset," "primary progressive").
  
  
  RESULTS
  The MOB effect was derived from "bout onset" MS patients (May/November ratio = 1.43; chi(2) = 17.32, df = 1, p = 0.000032).
  
  
  CONCLUSIONS
  An unspecified environmental effect in early development can influence both multiple sclerosis susceptibility and phenotype.
authors.affiliation: Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada. sadovnik@infinet.net
authors.forename: A D
authors.initials: AD
authors.lastname: Sadovnick
authors.forename: P
authors.initials: P
authors.lastname: Duquette
authors.forename: B
authors.initials: B
authors.lastname: Herrera
authors.forename: I M L
authors.initials: IM
authors.lastname: Yee
authors.forename: G C
authors.initials: GC
authors.lastname: Ebers
mesh_terms: D002170:Canada / Q000453:epidemiology; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D008297:Male; D020528:Multiple Sclerosis, Chronic Progressive / Q000453:epidemiology*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000453:epidemiology*; D036801:Parturition; D010641:Phenotype; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012621:Seasons; D012744:Sex Ratio; D035781:Siblings