What Is Microsatellite DNA?

The genomes of many living organisms have sections made up of short sequences of DNA that are repeated. These sections have certain characteristics, such as differences in their bases and molecular densities, that help distinguish them from other forms of DNA. These sorts of satellite DNA, which include minisatellite DNA and microsatellite DNA, have helped with DNA analysis techniques.

Microsatellite DNA

• Microsatellite DNA, also known as simple sequence repeats, is smaller than the minisatellite variety and is more uniformly distributed in the genome. They consist of short repeats that tend to be random and are two to four nucleotides long. They account for about 2 percent of a genome. Scientists believe that such sequences have come about as a result of slippage during DNA replication.

Examples

• Repeats of dinucleotide sequences are the most common of microsatellite sequence repeats, and make up about 0.5 percent of the genome. Of the bases that make up the human genome, repeats of sequences made up of cytosine and adenine, as well as sequences made up of thymine and guanine are more common than repeats of other sequences. Repeats of adenine and guanine sequences, and sequences of cytosine and thymine are also common. However, repeats of cytosine and guanine sequences, as well as guanine and cytosine sequences, are very rare.

Uses

• Considering that microsatellites provide a distinctive genetic marker, they have uses in identifying individuals and their backgrounds. They help to identify the genetic differences between individuals and populations. Microsatellite DNA is also useful in forensic applications to identify the origin of animals and of wildlife-based products.

Limitations

• While microsatellite DNA has its uses in identifying genetic differences between individuals, researchers must be careful about interpreting results from such tests. Microsatellite DNA can be highly variable and researchers can incorrectly interpret results. Also, microsatellite DNA analysis could lead researchers to wrongly conclude that there is not much genetic variability within a population, when in fact this is not true. Also, the genetic data that microsatellite DNA contain may not be the most representative of an organism's overall genetic makeup for study purposes.