Genetic marker

A genetic marker is a specific discovered single nucleotide polymorphism or SNP (or simply "mutation") of certain section of DNA of a specific genome. The SNP can either be associated with a known genetic disease, or, it can be in junk DNA that occurs in many individuals and thus be useful for population studies. For the later case, such a mutation would have had to have originated many of hundreds of generations previously and become widespread. Another kind of genetic marker would be a counted short tandem repeats (STRs), where the exact counts are generally inherited.

Related Topics:
Single nucleotide polymorphism - DNA - Genome - Junk DNA - Short tandem repeat

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Genetic markers are used in the studies of populations, such as studies of the migrations of peoples. In particular, genetic markers associated with the Y-chromosome persist along paternal lines and the genetic markers identified in mitochondrial DNA persist along maternal lines. Note that the Y-chromosome has about 25 million base pairs where mitochondrial DNA has about 16 thousand. This persistence is due to the fact that the Y-chromosome in male offspring and the mitochondria in all offspring are clones of the corresponding parent. Note that these SNP's are often in a region of junk DNA and so have no known impact on expressed genetic traits and no implications for biological function.

Related Topics:
Y-chromosome - Mitochondrial DNA - Clone

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STRs on the Y-chromosome are also widely used and are known as DNA Y-chromosome Segment (DYS). They necessarily fall in the category of junk DNA.

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A paternal example of a genetic marker would be the M343 marker. This mutation would have originated in a Y chromosome replication in a cell of an individual male and then ended up in at least one of his sperm cells which subsequently achieved fertilization in his mate and live birth of a male offspring.

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