Evidence for autism spectrum disorder in Jacobsen syndrome: identification of a candidate gene in distal 11q.

PURPOSE: Jacobsen syndrome, also called the 11q terminal deletion disorder, is a contiguous gene disorder caused by the deletion of the end of the long arm of chromosome 11. Intellectual skills range from low average to severe/profound intellectual disability and usually correlate with deletion size. Comprehensive genotype/phenotype evaluations are limited, and little is known about specific behavioral characteristics associated with 11q terminal deletion disorder.
METHODS: In this prospective study, 17 patients with 11q terminal deletion disorder underwent cognitive and behavioral assessments. Deletion sizes were determined by array comparative genomic hybridization.
RESULTS: Deletion sizes ranged from 8.7 to 14.5 Mb across the patients. We found that 8 of 17 patients (47%) exhibited behavioral characteristics consistent with an autism spectrum disorder diagnosis. There was no correlation between deletion size and the presence of autism spectrum disorder, implicating at least one predisposing gene in the distal 8.7 Mb of 11q. The findings from three additional patients with autistic features and "atypical" distal 11q deletions led to the identification of an autism "critical region" in distal 11q containing four annotated genes including ARHGAP32 (also known as RICS), a gene encoding rho GTPase activating protein.
CONCLUSION: Results from this study support early autism spectrum disorder screening for patients with 11q terminal deletion disorder and provide further molecular insights into the pathogenesis of autism spectrum disorder.