Using gene map science to evaluate the genetic map and eliminate disease

Locating Genes That Cause Genetic Diseases

When medical researchers want to investigate serious genetic diseases, they have to find ways to locate the corresponding risk genes. There are relatively few of these risk genes out of the 100,000 genes in the human cell, so it obviously is not an easy task. In order to find specific genes, they resort to analysis of genetic linkages and genetic associations.

Genetic Linkage analysis enables researchers to limit their search zone to areas in the genetic map with high probabilities of risk genes being present. In this procedure, researchers use genetic markers, which are essentially landmarks in the genetic map of the human DNA. A marker describes the variations that may be observed when a mutation occurs at a particular location, as for example, in a gene for a visible characteristic like hair color or a not-so-visible characteristic like a disease.

Researchers look for markers that consistently occur in persons having a disease and consistently do not occur in persons without that disease. When they find such a marker, they infer that the risk gene must be near the marker. Researchers will need DNA from closely-related individuals, both affected and unaffected by the disease.

Having identified its general location, researchers then perform Genetic Association analysis to get closer to the specific location of the risk gene. The testing here is done on candidate genes or small sub-sections of the identified genetic region, again comparing the DNA of affected and unaffected groups, all of whom are unrelated.

In genetic linkage analysis, it is like finding the district in a large city where a person you know only as David might be residing, and in association analysis, it is narrowing your search to one or two nearby streets. The only thing left to do is knock on doors until you find David.


 

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Genetic Markers

You know how an interstate map can guide you from one city to another. A genetic map is like that, and it guides researchers toward their target gene. Just as there are landmarks in interstate maps, there also are landmarks in genetic maps known as genetic markers...
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Gene

A hereditary unit that occupies a certain position on a chromosome; a unit that has one or more specific effects on the phenotype, and can mutate to various allelic forms.

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