Fragile sites

Pathology
A high level of cytogenetic expression of the rare folate-sensitive fragile site FRA12A is significantly associated with mental retardation. (#17236128#)
DIP2B, a brain-expressed gene, may mediate the neurocognitive problems associated with FRA12A. (#17236128#)
References
Winnepenninckx B, Debacker K, Ramsay J, Smeets D, Smits A, FitzPatrick DR, Kooy RF. CGG-repeat expansion in the DIP2B gene is associated with the fragile site FRA12A on chromosome 12q13.1. Am J Hum Genet. (...)

Common fragile sites (cFSs) are related to cancer development.
FRA16D localized in the tumor-suppressor gene WWOX that is altered by deletions or loss of heterozygosity (LOH) in many cancers.
References
Sbrana I, Veroni F, Nieri M, Puliti A, Barale R. Chromosomal fragile sites FRA3B and FRA16D show correlated expression and association with failure of apoptosis in lymphocytes from patients with thyroid cancer. Genes Chromosomes Cancer. 2006 May;45(5):429-36. PMID: (...)

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 (...)

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 (...)

CFS
Common fragile sites (CFS) are nonstaining gaps or breaks in chromosomes that are expressed under conditions inducing replicative stress. CFS have been suggested to play a role in epithelial cancers by their association with loss of heterozygosity, loss of gene expression, and/or gene amplification in the form of homogeneously staining regions (hsrs).
Pathology
In oral squamous-cell carcinomas (OSCC), amplification of chromosomal band 11q13 occurs in the form of an hsr. CFS flanking (...)

The novel aphidicolin-inducible common fragile site FRA9G maps to chromosomal band 9p22.2.
The fragile DNA sequence extends over a genomic region of approximately 300 kb within the C9orf39 (chromosome 9 open reading frame 39) gene.
Analysis of incidence in healthy individuals showed that FRA9G is commonly expressed in the population.
Heterozygous BRCA2 mutation carriers exhibit an almost sevenfold increase of FRA9G expression compared to an unrelated control population group.
See also (...)

References
Letessier A, Garrido-Urbani S, Ginestier C, Fournier G, Esterni B, Monville F, Adelaide J, Geneix J, Xerri L, Dubreuil P, Viens P, Charafe-Jauffret E, Jacquemier J, Birnbaum D, Lopez M, Chaffanet M. Correlated break at PARK2/FRA6E and loss of AF-6/Afadin protein expression are associated with poor outcome in breast cancer. Oncogene. 2007 Jan 11;26(2):298-307. PMID: #16819513#
See also
common fragile sites (...)

Common fragile sites (CFSs) are regions of chromosomal break that may play a role in oncogenesis. The most frequent alteration occurs at FRA3B, within the FHIT gene, at chromosomal region 3p14.
FRA3B localized in the tumor-suppressor gene FHIT that is altered by deletions or loss of heterozygosity (LOH) in many cancers.
References
Sbrana I, Veroni F, Nieri M, Puliti A, Barale R. Chromosomal fragile sites FRA3B and FRA16D show correlated expression and association with failure of (...)

CFS

The molecular basis of the fragility of common fragile sites (CFS) and their role in chromosome instability and in altered expression of associated genes in cancer cells have not yet been clarified.
FRA1H is the first characterized CFS the expression of which is not induced by aphidicolin but instead by DAPI. 5-azaC, 5-azadC, and Ad12 induce a CFS with the same cytogenetic location.
This CFS extends for approximately 10 Mb, and is therefore one of the largest characterized CFSs.
FRA1H (...)