Website Search
ID 552

Copy Number Variants

Humans differ not only at the level of DNA sequence. It has been recently discovered that humans can also differ in the number of copies of each gene. These are called copy number variants.
We carry two copies of most genes – one on the mother’s chromosome and one on the father’s chromosome. Occasionally alterations in a chromosome can lead to the gain or a loss of one copy. A deletion can occur when a fragment of DNA is lost – either during copying, or when the genes are shuffles during meiosis. By the same mechanisms, a duplication can occur, whereby which we gain an additional copy of a gene. Deletions and duplications of greater than 1,000 nucleotides are called copy number variants. A difference in the copy number of a gene can increase or decrease the level of that gene’s activity. For example, when a copy of a gene is deleted, the cell may produce half as much protein as compared to a normal cell. There are many diseases that are cause by changes in gene copy number. The most well-know is Down Syndrome, which is caused by having an extra copy of chromosome 21.
cnv, cnp, cns, cnps, copy number variants, copy number variation, copy number variance, copy number polymorphisms, polymorphisms, mutation, sebat, cshl, autism, Down Syndrome, 21, chromosome
Creative Commons License This work by Cold Spring Harbor Laboratory is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

Related content:

2192. Copy number variants
Professor Judith Rapoport introduces copy number variants, which are deletions and insertions in chromosomes.
553. Whole Genome Association
Special techniques are used for screening each individual’s genome for millions of different SNPs. This kind of comparison is referred to as a genome-wide association study.
2194. Copy number variants - environment
Professor Judith Rapoport discusses the issue of how copy number variants arise. Some are inherited and others are de novo (first occurrence).
2193. Copy number variants - random?
Professor Judith Rapoport discusses how copy number variants may be inherited and are not necessarily random.
2195. De novo variants and genetic screening
Professor Judith Rapoport discusses the use of screening for copy number variants to detect potential problems during pregnancy.
793. Whole Genome Association
Jonathan Sebat, a researcher at Cold Spring Harbor Laboratory, discusses how association studies are used to determine the causes of genetic disorders.
16934. Gene Copy Number Variation in SMA
Dr. Sumner explains copy number variation of the SMN2 gene may influence disease severity.
2197. We All Have Rare Structural Variants
Professor Judith Rapoport explains that we all have rare structural variants, which may have been an evolutionary mechanism driving larger brain sizes,
15897. Down syndrome
People with Down Syndrome (DS) have an excess of genetic material in their cells. The vast majority of people with this syndrome have an extra copy of chromosome 21. Down syndrome is one of the most commonly occurring genetic birth defects, and it is the
15944. What causes Down syndrome?
People with Down Syndrome (DS) have an excess of genetic material in their cells.
Cold Spring Harbor Laboratory
CSHL HomeAbout CSHLResearchEducationPublic EventsNewsstandPartner With UsGiving