To test the spectrum hypothesis--postulating that clinical and non-clinical samples are primarily differentiated by mean-level differences--, this study evaluates differences in parent-rated temperament, personality and maladjustment among a low-symptom (N = 81), a high-symptom (N = 94) ASD-group, and a comparison group (N = 500). These classic…

The broad autism phenotype (BAP) is a set of personality and language characteristics that reflect the phenotypic expression of the genetic liability to autism, in non-autistic relatives of autistic individuals. These characteristics are milder but qualitatively similar to the defining features of autism. A new instrument designed to measure the…

To probe the specificity of traits that might be conceptualised as the broader phenotype of autism, parents of subjects with autism from simplex and multiplex families as well as parents of subjects with obsessive-compulsive disorders (OCD), early onset schizophrenia (EOS) and mental retardation (MR) were assessed using the Personality Style and…

The present paper documents the development of autism/autistic spectrum disorder in a consecutive series of nine high-risk infants followed prospectively from 6 months of age. Evidence is provided for two broadly defined subgroups: the first subgroup (n = 6) showed a decrease in IQ between 12 and 24 or 36 months (from average/near average to…

Autism susceptibility genes likely have effects on continuously distributed autism-related traits, yet few measures of such traits exist. The Broader Phenotype Autism Symptom Scale (BPASS), developed for use with affected children and family members, measures social motivation, social expressiveness, conversational skills, and flexibility. Based…

In contrast to typically developing children, children with autism rarely exhibit cooperative social behavior. To examine whether this problem reflects global developmental delays or autism-specific deficits, the present study compared cooperation, emotional understanding, personality characteristics, and social behavior of 10 children with autism…

The objective of this review is to clarify the role of matching in family genetic studies of autism as a way of defining endophenotypes for linkage analysis. The concept of a confounding variable is reviewed and the importance of considering these in family studies of three endophenotypes in autism are considered: cognitive/language impairments,…