Williams-Beuren syndrome is a microdeletion syndrome involving genes at 7q11.23. DNA testing consists of deletion analysis of the ELN gene. Deletions or mutations in the ELN gene are thought to underlie the cardiovascular phenotype. Haplosufficiency for other genes close to ELN, that are typically involved in the microdeletion, are thought to underlie the visuospatial disibility and some of the other features frequently observed in individuals with this syndrome. Among patients with the clinical features of Williams-Beuren syndrome, MLPA will detect a deletion in greater than 90%.