La revue Epidemiology propose un dossier sur l’autisme dans son numéro de juillet 2011. Les articles traitents d’éventuels facteurs de risque et des questions étiologiques.

Les articles peuvent être consultés sur le site de l’éditeur.

1. Engel SM, Daniels JL. On the complex relationship between genes and environment in the etiology of autism. Epidemiology ;2011 (Jul) ;22(4):486-488.

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2. Schmidt RJ, Hansen RL, Hartiala J, Allayee H, Schmidt LC, Tancredi DJ, Tassone F, Hertz-Picciotto I. Prenatal vitamins, one-carbon metabolism gene variants, and risk for autism. Epidemiology ;2011 (Jul) ;22(4):476-485.

BACKGROUND : Causes of autism are unknown. Associations with maternal nutritional factors and their interactions with gene variants have not been reported. METHODS : Northern California families were enrolled from 2003 to 2009 in the CHARGE (CHildhood Autism Risks from Genetics and Environment) population-based case-control study. Children aged 24-60 months were evaluated and confirmed to have autism (n = 288), autism spectrum disorder (n = 141), or typical development (n = 278) at the University of California-Davis Medical Investigation of Neurodevelopmental Disorders Institute using standardized clinical assessments. We calculated adjusted odds ratios (ORs) for associations between autism and retrospectively collected data on maternal vitamin intake before and during pregnancy. We explored interaction effects with functional genetic variants involved in one-carbon metabolism (MTHFR, COMT, MTRR, BHMT, FOLR2, CBS, and TCN2) as carried by the mother or child. RESULTS : Mothers of children with autism were less likely than those of typically developing children to report having taken prenatal vitamins during the 3 months before pregnancy or the first month of pregnancy (OR = 0.62 [95% confidence interval = 0.42-0.93]). Significant interaction effects were observed for maternal MTHFR 677 TT, CBS rs234715 GT + TT, and child COMT 472 AA genotypes, with greater risk for autism when mothers did not report taking prenatal vitamins periconceptionally (4.5 [1.4-14.6] ; 2.6 [1.2-5.4] ; and 7.2 [2.3-22.4], respectively). Greater risk was also observed for children whose mothers had other one-carbon metabolism pathway gene variants and reported no prenatal vitamin intake. CONCLUSIONS : Periconceptional use of prenatal vitamins may reduce the risk of having children with autism, especially for genetically susceptible mothers and children. Replication and mechanistic investigations are warranted.

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3. Stoltenberg C. Autism spectrum disorders : is anything left for the environment ?. Epidemiology ;2011 (Jul) ;22(4):489-490.

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4. Zerbo O, Iosif AM, Delwiche L, Walker C, Hertz-Picciotto I. Month of conception and risk of autism. Epidemiology ;2011 (Jul) ;22(4):469-475.

BACKGROUND : Studies of season of birth or season of conception can provide clues about etiology. We investigated whether certain months or seasons of conception are associated with increased risk of autism spectrum disorders, for which etiology is particularly obscure. METHODS : The study population comprises 6,604,975 children born from 1990 to 2002 in California. Autism cases (n = 19,238) were identified from 1990 through 2008 in databases of the California Department of Developmental Services, which coordinates services for people with developmental disorders. The outcome in this analysis was autism diagnosed before the child’s sixth birth date. The main independent variables were month of conception and season of conception (winter, spring, summer, and fall). Multivariate logistic regression models were used to estimate odds ratios (ORs) with their 95% confidence intervals (CIs) for autism by month of conception. RESULTS : Children conceived in December (OR = 1.09 [95% CI = 1.02-1.17]), January (1.08 [1.00-1.17]), February (1.12 [1.04-1.20]), or March (1.16 [1.08-1.24]) had higher risk of developing autism compared with those conceived in July. Conception in the winter season (December, January, and February) was associated with a 6% (OR = 1.06, 95% CI = 1.02-1.10) increased risk compared with summer. CONCLUSIONS : Higher risks for autism among those conceived in winter months suggest the presence of environmental causes of autism that vary by season.

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