   Monday 3 September 2007  Fragile sites are specific genomic
loci that are particularly prone to chromosomal breakage. Based
on their incidence in the human population, they are divided
into rare fragile sites occurring in less than 5% of all
individuals and common fragile sites being a constitutional
feature of the genome of probably all individuals.  The
chromosomal subband 11q23.3 harbors both the common fragile site
FRA11G and the rare fragile site FRA11B. FRA11G maps 0.8 Mb
proximal to the genomic region previously defined to be affected
by expression of FRA11B. Thus, the common and the rare fragile
sites at 11q23.3 encompass distinct genomic regions.  The region
of FRA11G is known to be involved in somatic and germline
recurrent aberrations, and it is conceivable that genetic damage
resulting from this fragile site might contribute to clinical
phenotypes.   - Fechter A, Buettel I, Kuehnel E, Savelyeva L,
Schwab M. Common fragile site FRA11G and rare fragile site
FRA11B at 11q23.3 encompass distinct ge