Between missing chunks of chromosomes and single nucleotide polymorphisms (SNPs) lies a vast middle ground of genomic alterations. Among these are copynumber variations (CNVs) - the differences between individuals in the number of copies of a genomic region. "The total nucleotide content that is encompassed by CNVs most certainly exceeds that of SNPs," says Stephen Scherer of The Hospital for Sick Children in Toronto.
The recent surge of interest in CNVs has induced a proliferation of technologies designed to detect them in normal DNA, congenital diseases, and cancer cells, in which copynumber changes may induce their unruly divisions.
Scientists have largely turned to comparative genomic hybridization (CGH) arrays, which involve hybridizing two genomes - one as a reference and one to be tested - that fluoresce in different colors. Measuring the color that dominates at a given region determines whether the test genome contains an insertion or deletion at that ...
