1. National Human Genome Research Institute National Institutes of Health Bethesda Maryland USA
2. Department of Genetic Medicine Johns Hopkins University School of Medicine Baltimore Maryland USA
3. Department of Pediatrics Johns Hopkins University School of Medicine Baltimore Maryland USA
4. Department of Neurogenetics Kennedy Krieger Institute Baltimore Maryland USA
5. Molecular Genetics Laboratory, Molecular Diagnostics Division London Health Sciences Centre London Ontario Canada
6. Greenwood Genetic Center Greenwood South Carolina USA
7. Department of Pathology and Laboratory Medicine Western University London Ontario Canada