Investigators:
- N. Carolyn Schanen, MD, PhD
- Naghmeh Dorrani, MS
- Suzanne M. Mann, PhD
Background: Numerous reports have implicated maternally-derived rearrangements of proximal chromosome 15q as significant risk factors for autism and autism-related disorders. The region undergoes gametic imprinting and thus, parent-of-origin specific gene expression. Whether it is dosage of a particular interval or gene, or involvement of a particular breakpoint that leads to the phenotype is unclear at present. We are currently studying the molecular characteristics of chromosome 15 duplications in a large patient cohort to delineate the relationship between these duplications and the clinical presentation.
What We're Doing
We are using a combination of molecular, cytogenetic, and microarray approaches to characterize the duplication regions. Roughly half of the duplication events arise because of the presence of a supernumerary marker chromosome while the remaining are interstitial duplications of the long arm.
Analysis of these unique patients may provide insight into the understanding of the autism spectrum disorders in chromosomally normal individuals. This project is part of the NIH-funded Collaborative Programs for Excellence in Autism Research and is being conducted with researchers at the University of California, Los Angeles.
Some of What We've Found
We have examined the duplications from more than 50 people with idic(15) or int dup(15) chromosomes. We have found that most, but not all, patients carrying duplications that are derived from their mothers copy of chromosome 15 are autistic. More than half have seizures at some point and for many children, the seizures are difficult to manage. Clinically, most children experience language delays with some improvement in language skills in childhood.
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