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What Is Gene Mapping?

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  • Written By: Mary Elizabeth
  • Edited By: Bronwyn Harris
  • Last Modified Date: 25 September 2014
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A gene is a set of instructions for making a molecule given through a set of nucleotides in a molecule of DNA or RNA, with most of the DNA existing on the 23 pairs of chromosomes in the nucleus of each human cell. The bases of the nucleotides—which are adenine, cytosine, guanine, and thymine—define the information in the gene and the molecular product, often a protein.

Gene mapping refers to one of two different ways of definitively locating the gene on a chromosome. The first type of gene mapping is also called genetic mapping. Genetic mapping refers to the use of linkage analysis to determine how two genes on a chromosome relate in their positions. Physical mapping, the other type of gene mapping, locates genes by their absolute positions on a chromosome using any technique available. Once a gene is located, it can be cloned, its DNA sequence determined, and its molecular product studied.

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The first report of mapping a gene to a human autosome was published in 1968 by Roger Donahue and associates. Using a linkage analysis, he was able to estimate the genetic distance of 2.5 map units between two loci or gene locations on chromosome 1. In 1971, chromosome banding techniques were developed, which opened the way for researchers to be able to identify more types of alterations, included insertions, deletions, and translocations, as well as mapping to position. In connection with this, restriction fragment length polymorphism (RFLP) analysis was developed and led by the early 1990s to the identification of a number of genes associated with disease in humans. A complementary technique, fluorescence in situ hybridization, developed about the same time, also contributed to the mapping efforts.

An example of this process in application is the work done with the gene for cystic fibrosis. The cystic fibrosis gene was mapped by linkage analysis in 1985. This paved the way for its cloning in 1989 by Francis Collins and his associates. This led to a better understanding of the cause of the disease.

The foundation of gene mapping also laid the foundation for the Human Genome Project. The idea of sequencing the entire human genome was explored in the 1980s, but was not universally thought to be feasible. Impetus from the U.S. Department of Energy along with the National Institutes of Health (NIH) helped foster the 1990 launch of the project. The technical achievements mentioned above contributed to the project’s momentum. The project was completed in 2003.

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PinkLady4
Post 3

In addition to using genetic mapping to break the genetic code,there are other studies to determine how to conquer some diseases.

Telemeres are attached to the ends of all the chromosomes. They are protective bits of DNA. Dr. Elizabeth Blackburn, PhD has found links between shorter telomeres and risk for cardiovascular disease, diabetes, some cancers, depression, osteoarthritis, and osteoporosis.

Research continues to find out how telomeres are so important at the cellular stage to prevent stress, aging and chronic diseases.

poppyseed
Post 2

You know it does seem that any day now we are going to be able to find the cures for such diseases as AIDS and cancer, and it is all because of the revelation of the mapping of human genes!

I truly believe with all of my heart that before my generation dies out (and I’m a thirty something) that we will see these cures. That is if we can quit fighting each other over silly things long enough to focus on the knowledge that could get us there.

It truly is a miracle and utterly amazing to me that we have been given such aptitude to discover these teeny, tiny, wonderful pieces of creation to study and learn from. What a blessing!

oscar23
Post 1

Wait, people were mapping genes back in the 1960s? I thought this was a very modern development. What was gene mapping like back then? I have to admit, whenever I think about it today I picture some very futuristic process, but perhaps I'm off? Does anybody know?

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