About one in 200 babies worldwide is born with a chromosomal abnormality and many of these children have mental retardation and learning disabilities. Chromosomal imbalances, such as deletions, microdeletions, translocations or inversions, underlie some of these disorders and the genetic diagnosis of these patients has conventionally relied on cytogenetic chromosomal analysis techniques, such as karyotyping, fluorescence in situ hybridization (FISH) or conventional comparative genomic hybridization (CGH).
