Association of Family History of Autoimmune Diseases and Autism Spectrum Disorders

OBJECTIVES: Recent studies suggest that familial autoimmunity plays a part in the pathogenesis of ASDs. In this study we investigated the association between family history of autoimmune diseases (ADs) and ASDs/infantile autism. We perform confirmatory analyses based on results from previous studies, as well as various explorative analyses. METHODS: The study cohort consisted of all of the children born in Denmark from 1993 through 2004 (689 196 children). Outcome data consisted of both inpatient and outpatient diagnoses reported to the Danish National Psychiatric Registry. Information on ADs in parents and siblings of the cohort members was obtained from the Danish National Hospital Register. The incidence rate ratio of autism was estimated by using log-linear Poisson regression. RESULTS: A total of 3325 children were diagnosed with ASDs, of which 1089 had an infantile autism diagnosis. Increased risk of ASDs was observed for children with a maternal history of rheumatoid arthritis and celiac disease. Also, increased risk of infantile autism was observed for children with a family history of type 1 diabetes. CONCLUSIONS: Associations regarding family history of type 1 diabetes and infantile autism and maternal history of rheumatoid arthritis and ASDs were confirmed from previous studies. A significant association between maternal history of celiac disease and ASDs was observed for the first time. The observed associations between familial autoimmunity and ASDs/infantile autism are probably attributable to a combination of a common genetic background and a possible prenatal antibody exposure or alteration in fetal environment during pregnancy. Pediatrics 2009; 124: 687-694