Mini- and Microsatellites
Claes Ramel
Department of Genetic and Cellular Toxicology, Stockholm University, Stockholm, Sweden
Abstract
While the faithful transmission of genetic information requires a fidelity and stability of DNA that is involved in translation into proteins, it has become evident that a large part of noncoding DNA is organized in repeated sequences, which often exhibit a pronounced instability and dynamics. This applies both to longer repeated sequences, minisatellites (about 10-100 base pairs), and microsatellites (mostly 2-4 base pairs). Although these satellite DNAs are abundantly distributed in all kinds of organisms, no clear function has been discerned for them. However, extension of trinucleotide microsatellite sequences has been associated with several severe human disorders, such as Fragile X syndrome and Huntington's disease. Rare alleles of a minisatellite sequence have been reported to be associated with the ras oncogene leading to an increased risk for several human cancers. A dynamic behavior of repeated DNA sequences also applies to telomeres, constituting the ends of the chromosomes. Repeated DNA sequences protect the chromosome ends from losing coding sequences at cell divisions. The telomeres are maintained by the enzyme telomerase. Somatic cells, however, lose telomerase function and gradually die. Cancer cells have activated telomerase and therefore they acquire immortality. -- Environ Health Perspect 105(Suppl 4):781-789 (1997)
Key words: minisatellites, microsatellites, amplification, genetic instability, fingerprinting, transpositions, recombination, mismatch repair, telomere
This paper was prepared as background for the Workshop on Susceptibility to Environmental Hazards convened by the Scientific Group on Methodologies for the Safety Evaluation of Chemicals (SGOMSEC) held 17-22 March 1996 in Espoo, Finland. Manuscript received at EHP 5 November 1996; accepted 18 November 1996.
Address correspondence to Dr. C. Ramel, Department of Genetic and Cellular Toxicology, University of Stockholm, S-106 91 Stockholm, Sweden. Telephone: 46 8 16 20 51. Fax: 46 8 612 40 04. E-mail: claes.ramel@genetics.su.se
Abbreviations used: AR, androgen receptor; HNPCC, hereditary nonpolyposis colon cancer; IDDM, type I diabetes mellitus; IGM, immunoglobulin heavy-chain gene; INS, insulin gene; LINE, long interspersed element; MVR, minisatellite variant repeat; PCR, polymerase chain reaction; RAP, repeat associated point mutations; RIP, repeat-induced point mutations; VNTR, variable number of tandem repeats.
[Table of Contents]
[Full Article]
Last Update: June 16, 1997