| The apparent increase in the prevalence of the autistic spectrum disorders (ASD) indicates an urgent public health concern which has sparked intense study of the possible etiologies of the condition. One area of interest is how parental age at delivery can affect an offspring's risk of developing an ASD. Maternal age at delivery was evaluated in a retrospective chart review of 226 individuals with an autistic spectrum disorder. A bimodal distribution of maternal age was seen, especially in a subgroup with low cognitive ability and another with a family history of psychiatric disorders. A similar bimodal distribution has been previously established in the maternal age distribution of individuals with Down syndrome. Therefore, this finding suggests an etiologic mechanism of non-disjunction in a subgroup of the individuals with an ASD. It also suggests a pathophysiologic mechanism of abnormal gene dosage, either from low-level mosaicism or imprinting abnormalities caused by uniparental dismay. |
