The Human Genome Project, which aims to map out every gene human beings possess, will have effects throughout the biological sciences (Collins and Jegalian, 1999). The complete DNA sequencing of the entire human organism will answer a host of questions on how organisms evolved and how to treat a wide range of medical disorders, as well as determining whether it will ever be possible to completely synthesize human life.
Microsatellites are short sequences of repetitive DNA that are tandemly repeated and qualitatively similar, and are important in gene mapping (Hancock, 1996, p. 191). Other simple short sequences exist, but are not repeated tandemly. Microsatellites are widespread in the human genome. Many microsatellites occur as mono- and dinucleotides, where (A/T)n is the most common motif. Microsatellites containing strings of A bases also dominate the frequency distribution of longer motif satellites.
This review will look at some properties of microsatellites and at some of the information about the human genome that can be gained from the study of microsatellites, what they can tell us about the evolution of mankind, and how they can be used to examine the genetic basis of disease.
Microsatellites are often used as markers in studying the evolution of disease (Macauba, Jin, Hallmayer, Kimura and Mignot, 1997). These researchers looked at the mutation pattern of the microsatellites DQCAR, located in the HLA class II region and tightly linked to HLA-DQB1. While previous studies have shown a very low level of size variation in DQCAR alleles within a subfamily of HLA-DQ subtypes (DQ1), DQCAR alleles in non-(DQ1) subtypes showed a high degree of polymorphism. Using sequence analysis, these researchers showed that DQ1-associated DQCAR alleles have a single C to A nucleotide substitution interrupting a CA repeat array. They also noted frequent CA to GA mutations in DQ1-associated microsatellites with identical allele ...