Neuropsychological functioning of 30 siblings of children with autism (AU-S), 28 siblings of children with mental retardation of (MR-S), and 30 siblings of children with developmental language delay (DLD-S) was compared. Two siblings, both AU-S, received diagnoses of pervasive developmental disorder (PDD). More siblings with cognitive disabilities were found in DLD-S than in AU-S. However, these differences disappeared after excluding diagnosed siblings or after accounting for family membership. In sum, despite the elevated incidence of PDD among AU-S, the neuropsychological functioning of the remaining siblings did not convey specific characteristics related to the genetic risk associated with autism, in contrast to the cognitive functioning of the DLD-S, which did reflect a genetic risk.
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Acknowledgments This study was supported by the United States-Israel Binational Science Foundation (BSF) grants number 94-66/3 and 97-00073, the Diller Foundation, and by fellowships to Tammy Pilowsky from the Silvia and Milton Bard Fund for Pediatric Neuropsychology, and the Levin Center for the Normal and Psychopathological Development of the Child and Adolescent. We are grateful to the families who participated in the study, to Idit Paran, Yasmin Gover, Osnat Doppelt, and to Dee B. Ankonina for her editorial assistance. These data were presented at the International Meeting For Autism Research, Sacramento, USA, May 2004, and were a part of the doctoral dissertation of Tammy Pilowsky.
- Behavioral genetics
- Broad phenotype
- Neuropsychological functioning