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Tracy Hampton, PhD

JAMA. 2007;297:1539-1540.

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

Scientists have generally thought that while humans have varied traits and physical appearances, the DNA sequence among individuals is 99.9% identical. Not so, according to a relatively new field of genetic study that has revealed that many individuals' chromosomes harbor deletions and duplications of large DNA segments varying in size from thousands to millions of DNA bases.

The 23 chromosomes of the human genome contain a variety of copy number variations, deletions and duplications of large DNA segments (indicated in blue). Many copy number variations have no effect on health, but others are associated with occurrence of disease.

Such copy number variations (CNVs) of genetic material can lie within or around genes, leading to gene disruption or dosage imbalances, or outside of genes, which may or may not affect gene expression. Research is beginning to show that CNVs can be involved with disease occurrence and drug response . . . [Full Text of this Article]

TRACKING CNVs