Array Comparative Genomic Hybridization in Cytogenetics and Molecular Genetics

Abstract

Variations in the human genome range from single nucleotide changes to whole chromosomal aneuploidies. De novo single nucleotide changes are estimated to occur at a rate of 1.7 × 10−8 per nucleotide in every generation (Kondrashov, Hum Mutat 21(1):12–27, 2003). These sequence variations include coding and noncoding nucleotide changes that may or may not be important in disease. At the opposite end of the spectrum are large segmental genomic rearrangements (inversions and translocations) and copy number changes (CNCs), that is, aneuploidies, marker chromosomes, and large interstitial deletions and duplications. The portion of the human genome that shows variations in segmental genomic copy numbers between individuals accounts for 12% of the DNA. Moreover, de novo copy number changes in newborns are expected to occur once in every 8 births for deletions and once in every 50 births for duplications (van Ommen, Nat Genet 37(4):333–334, 2005).