title: Risk of Psychiatric and Neurodevelopmental Disorders Among Siblings of Probands With Autism Spectrum Disorders.
abstract: Previous research has focused on examining the familial clustering of schizophrenia, bipolar disorder, and autism spectrum disorders (ASD). Little is known about the clustering of other psychiatric and neurodevelopmental disorders among siblings of persons with ASD.
  
  
  
  To examine the risk for psychiatric and neurodevelopmental disorders among full siblings of probands with ASD.
  
  
  
  The Finnish Prenatal Study of Autism and Autism Spectrum Disorders used a population-based cohort that included children born from January 1, 1987, to December 31, 2005, who received a diagnosis of ASD by December 31, 2007. Each case was individually matched to 4 control participants by sex and date and place of birth. The siblings of the cases and controls were born from January 1, 1977, to December 31, 2005, and received a diagnosis from January 1, 1987, to December 31, 2009. This nested case-control study included 3578 cases with ASD with 6022 full siblings and 11 775 controls with 22 127 siblings from Finnish national registers. Data were analyzed from March 6, 2014, to February 12, 2016.
  
  
  
  The adjusted risk ratio (RR) for psychiatric and neurodevelopmental disorders among siblings of probands with ASD vs siblings of matched controls. Additional analyses were conducted separately for ASD subgroups, including childhood autism, Asperger syndrome, and pervasive developmental disorders not otherwise specified. Analyses were further stratified by sex and intellectual disability among the probands.
  
  
  
  Among the 3578 cases with ASD (2841 boys [79.4%]) and 11 775 controls (9345 boys [79.4%]), 1319 cases (36.9%) and 2052 controls (17.4%) had at least 1 sibling diagnosed with any psychiatric or neurodevelopmental disorder (adjusted RR, 2.5; 95% CI, 2.3-2.6). The largest associations were observed for childhood-onset disorders (1061 cases [29.7%] vs 1362 controls [11.6%]; adjusted RR, 3.0; 95% CI, 2.8-3.3), including ASD (374 cases [10.5%] vs 125 controls [1.1%]; adjusted RR, 11.8; 95% CI, 9.4-14.7), tic disorders (28 cases [0.8%] vs 24 controls [0.2%]; adjusted RR, 4.3; 95% CI, 2.3-8.2), attention-deficit/hyperactivity disorder (189 cases [5.3%] vs 180 controls [1.5%]; adjusted RR, 3.7; 95% CI, 2.9-4.7), learning and coordination disorders (563 cases [15.7%] vs 697 controls [5.9%]; adjusted RR, 3.2; 95% CI, 2.8-3.6), intellectual disability (104 cases [2.9%] vs 137 controls [1.2%]; adjusted RR, 3.1; 95% CI, 2.3-4.2), conduct and oppositional disorders (180 cases [5.0%] vs 221 controls [1.9%]; adjusted RR, 2.8; 95% CI, 2.2-3.5), and emotional disorders with onset specific to childhood (126 cases [3.5%] vs 157 controls [1.3%]; adjusted RR, 2.6; 95% CI, 1.9-3.4). Autism spectrum disorders were also associated with schizophrenia spectrum disorders, affective disorders, anxiety disorders, and other neurotic and personality disorders among siblings.
  
  
  
  Psychiatric and neurodevelopmental disorders cluster among siblings of probands with ASD. For etiologic research, these findings provide further evidence that several psychiatric and neurodevelopmental disorders have common risk factors.
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Jokiranta-Olkoniemi
authors.affiliation: Department of Psychiatry, Columbia University Medical Center, New York State Psychiatric Institute, New York, New York.
authors.forename: Keely
authors.initials: K
authors.lastname: Cheslack-Postava
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland.
authors.forename: Dan
authors.initials: D
authors.lastname: Sucksdorff
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland.
authors.forename: Auli
authors.initials: A
authors.lastname: Suominen
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland.
authors.forename: David
authors.initials: D
authors.lastname: Gyllenberg
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland.
authors.forename: Roshan
authors.initials: R
authors.lastname: Chudal
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland.
authors.forename: Susanna
authors.initials: S
authors.lastname: Leivonen
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland3National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.affiliation: Department of Psychiatry, Columbia University Medical Center, New York State Psychiatric Institute, New York, New York4Department of Epidemiology, Columbia University Mailman School of Public Health, New York, New York.
authors.forename: Alan S
authors.initials: AS
authors.lastname: Brown
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku University Hospital, Turku, Finland2Department of Psychiatry, Columbia University Medical Center, New York State Psychiatric Institute, New York, New York.
authors.forename: Andre
authors.initials: A
authors.lastname: Sourander
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D020817:Asperger Syndrome / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D000067877:Autism Spectrum Disorder / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D016022:Case-Control Studies; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D065886:Neurodevelopmental Disorders / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D012306:Risk; D035781:Siblings / Q000523:psychology; D055815:Young Adult