DNA Copy Number Plays Role in Autism Spectrum Disorders

Study finds most copy number variants are smaller than microscopic resolution

THURSDAY, March 15 (HealthDay News) -- Patients with autism spectrum disorders are more likely to have extra copies of some DNA regions compared with their parents, suggesting that such germline mutations may play a primary role in the disease, according to the results of a study published March 15 in Sciencexpress, the early online edition of Science.

Jonathan Sebat, Ph.D., of Cold Spring Harbor Laboratory in Cold Spring Harbor, N.Y., and colleagues used array-based DNA technology to identify de novo copy number variation in 264 families with autism. This method can detect variations in DNA copy number in parents and their offspring at a much higher resolution than cytogenetic analyses. The study included 118 "simplex" families having one affected child, 47 "multiplex" families with multiple affected siblings, and 99 unaffected families.

The investigators found that copy number variants, most of which were smaller than microscopic resolution, were present in 10 percent of simplex families, 2 percent of multiplex families and 1 percent of control families. The affected regions were heterogeneous and included mutations of single genes.

"These findings establish de novo germline mutation as a more significant risk factor for autism spectrum disorders than previously recognized," the authors write. "Our findings highlight how methods for directly detecting copy number variation genome-wide provides a powerful alternative to traditional gene-mapping approaches for discovering genetic risk factors in autism and in other disorders of complex etiology."

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