Sex differences and within-family associations in the broad autism phenotype.

While there is a strong sex bias in the presentation of autism, it is unknown whether this bias is also present in subclinical manifestations of autism among relatives, or the broad autism phenotype. This study examined this question and investigated patterns of co-occurrence of broad autism phenotype traits within families of individuals with autism. Pragmatic language and personality features of the broad autism phenotype were studied in 42 fathers and 50 mothers of individuals with autism using direct assessment tools used in prior family studies of the broad autism phenotype. Higher rates of aloof personality style were detected among fathers, while no sex differences were detected for other broad autism phenotype traits. Within individuals, pragmatic language features were associated with the social personality styles of the broad autism phenotype in mothers but not in fathers. A number of broad autism phenotype features were correlated within spousal pairs. Finally, the associations were detected between paternal broad autism phenotype characteristics and the severity of children's autism symptoms in all three domains (social, communication, and repetitive behaviors). Mother-child correlations were detected for aspects of communication only. Together, the findings suggest that most features of the broad autism phenotype express comparably in males and females and raise some specific questions about how such features might inform studies of the genetic basis of autism.