Autism spectrum disorders in relation to parental occupation in technical fields.

A previous study reported that fathers of children with autism spectrum disorders (ASD) were more likely to work as engineers, requiring "systemizing skills," and suggesting a distinct phenotype, but alternatively this may have been related to selection biases. We conducted a population-based study to explore whether fathers, or mothers, of children with ASD are over-represented in fields requiring highly technical skills. Subjects included 284 children with ASD and 659 gender-matched controls, born in 1994 in the San Francisco Bay Area. Parental occupation and industry were abstracted verbatim from birth certificates. Engineering, computer programming, and science were examined as highly technical occupations. To limit bias by parental socio-economic status, we selected a referent group of occupations that seemed professionally similar but of a less technical nature. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated by logistic regression, adjusting for parental age, education, and child race. Mothers of cases were somewhat more likely to work in hi-tech occupations (6.7%) than mothers of controls (4.0%, P=0.07), but little difference was observed among fathers, nor for engineering separately. Compared to parents in other "white collar" occupations, the adjusted OR for highly technical occupations among mothers was 2.5 (95% CI: 1.2-5.3) and among fathers was 1.3 (95% CI: 0.79-2.1), with no evidence of a joint effect observed. Our results regarding maternal occupation in technical fields being associated with ASD in offspring suggest further study to distinguish parental occupation as a phenotypic marker of genetic loading vs. other social or exposure factors.