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.
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- ID: 552
- Source: DNALC.G2C
Professor Judith Rapoport introduces copy number variants, which are deletions and insertions in chromosomes.
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.
Professor Judith Rapoport discusses the issue of how copy number variants arise. Some are inherited and others are de novo (first occurrence).
Professor Judith Rapoport discusses how copy number variants may be inherited and are not necessarily random.
Professor Judith Rapoport discusses the use of screening for copy number variants to detect potential problems during pregnancy.
Jonathan Sebat, a researcher at Cold Spring Harbor Laboratory, discusses how association studies are used to determine the causes of genetic disorders.
Dr. Sumner explains copy number variation of the SMN2 gene may influence disease severity.
Professor Judith Rapoport explains that we all have rare structural variants, which may have been an evolutionary mechanism driving larger brain sizes,
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
People with Down Syndrome (DS) have an excess of genetic material in their cells.