Homo sapiens

Minisatellites are structures found in centromeric and sub-telomeric regions of the genome. They consist of tandem repeats of a basic sequence motif of about 10 to 100 nucleotides. The size of a minisatellite is of the order of one kilobase. The number of repeat elements varies substantially from one individual to another. The rate of appearance of new alleles is very high; about a dozen loci with a germ-line mutation rate of 0.5 to 0.7% have been described.

These so-called hypermutable minisatellites are very useful for understanding recombination mechanisms and the replication of the human genome. Mutations are initiated by double-strand breaks.
Hypermutable minisatellites have been proposed as markers for the study of exposure to low doses of ionizing irradiation. The sequencing of six cosmids which contain hypermutable minisatellites will help characterize these exceptional sites. This sequence data will make it possible to compare the cosmids, and to identify neighboring genes, which could lead to functional studies of these sites.

This project is a collaboration with the IECH Laboratory, Institut de Genetique et Microbiologie, Universite Paris Sud, 91405 Orsay.