Research continues to try and pinpoint the etiological role of particular genes and brain structure in autistic spectrum disorder (ASD), but despite a host of biological, genetic and neuropsychological research, the symptom profile of pervasive developmental disorders (PDDs) are not yet linked to etiological theory. Debate continues around whether…

We tested whether developmental coordination disorder (DCD) and mixed receptive expressive language disorder (RELD) are valid diagnoses by assessing whether they are separated from each other, from other childhood disorders, and from normality by natural boundaries termed zones of rarity. Standardized measures of intelligence, language, motor…