Brief Report: Relationship between non-verbal IQ and gender in autism.

It has been proposed that females at risk for autism are protected in some way, so that only those with the greatest genetic liability are affected. Consequently, affected male siblings of females with autism should be more impaired than affected male siblings of male probands. One hundred and ninety-four (194) families with a single child with autism (simplex, SPX) and 154 families with more than one child with autism (multiplex, MPX) were examined on measures of severity, including non-verbal IQ.

Investigating the structure of the restricted, repetitive behaviours and interests domain of autism.

Background: The Restricted, Repetitive Behaviours and Interests (RRBIs) are represented in the DSM-IV and measured by the Autism Diagnostic Interview-Revised (ADI-R) as one of the three homogeneous symptom categories of Pervasive Developmental Disorders. Although this conceptualisation is well accepted in the field, the grouping of symptoms is based primarily on clinical judgment rather than on empirical evidence.

Methods: The objective of this study was to examine the factor structure of the RRBI domain of autism.

Pregnancy and birth complications in autism and liability to the broader autism phenotype.

Objective: To understand better the relationship between pregnancy and birth complications and genetic factors in autism.

Method: The sample included 78 children with an autism spectrum disorder and 88 unaffected siblings. A standardized interview was used to ask mothers about the pregnancy and birth of each child, and an overall index reflecting freedom from complications (termed "optimality") was determined.