title: Sibling sex ratio of individuals diagnosed with autism spectrum disorder as children.
abstract: OBJECTIVE
  To study the sex ratio (proportion of males) in siblings of individuals diagnosed with autism spectrum disorders (ASDs) as children.
  
  
  METHODS
  In the current study, we extended previous studies dealing with the androgen theory of autism and examined sex ratios in the siblings of 326 individuals with ASD (245 males, 81 females) who had been consecutively assessed at two Danish university clinics of child psychiatry during the 25-year period from 1960 to 1985.
  
  
  RESULTS
  Among the 513 siblings, 300 were males and 213 females. This yields a sex ratio of 0.585, which is significantly higher than the Danish live-birth sex ratio over the same period (0.514, p=0.001). The sibling sex ratio was not associated with the IQ in the autistic probands.
  
  
  CONCLUSIONS
  Our findings suggest a potential indirect confirmation of the androgen theory of autism.
authors: Department of Child and Adolescent Psychiatry, Bispebjerg University Hospital, Copenhagen, Denmark. sem01@bbh.hosp.dk
authors: Svend Erik
authors: SE
authors: Mouridsen
authors: Bente
authors: B
authors: Rich
authors: Torben
authors: T
authors: Isager
mesh_terms: D000653:Amniotic Fluid / Q000737:chemistry; D020817:Asperger Syndrome / Q000453:epidemiology* / Q000235:genetics / Q000378:metabolism; D001321:Autistic Disorder / Q000453:epidemiology* / Q000235:genetics / Q000378:metabolism; D002391:Catchment Area, Health; D002648:Child; D002675:Child, Preschool; D041321:Chromosomes, Human, X / Q000235:genetics; D003718:Denmark / Q000453:epidemiology; D005260:Female; D047109:Fetal Development; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000706:statistics & numerical data; D017678:Sex Distribution; D035781:Siblings; D013739:Testosterone / Q000032:analysis / Q000378:metabolism
chemical_list: D013739:Testosterone