All aberrations (gaps, breaks, translocations, deletions, inversions, duplications, rings, derivatives, additions, minutes/double minutes, fragile sites, marker chromosomes) were listed, even when present in a single cell only.
MSCs from Artemis-deficient mice exhibited more frequent double-strand breaks, translocations and fragmentations than did their WT littermates, yet retained a normal growth rate and ability to differentiate along the usual trilineage pathways.
Cytological studies by Barbara McClintock revealed that these phenotypes were the result of large scale chromosomal aberrations such as deletions, breaks, translocations, and initiation of breakage fusion cycles that lead to ring chromosomes, dicentrics, and other unstable chromosome features (McClintock 1931 , 1932 1938a, 1939; Rhoades and McClintock 1935; Stadler and Roman 1948).
In comparison, cells overexpressing Rad51 showed higher recombination frequencies (Lambert and Lopez, 2001), reduced DNA break frequencies, translocations, chromosome aberrations, decreased induction of apoptosis (Grandy et al, 2002; Raderschall et al, 2002b), stimulated tumorigenesis (Bertrand et al, 2003) and increased resistance to IR (Vispe et al, 1998).
The 200 kb breakage zone at ABL contains translocation break sites distributed anywhere between alternative exons 1a and 1b.
These may cause mutagenic damage (chromatid breaks, chromosome translocations, ane-uploidy, etc).
Since chromosomal breaks and translocations were considered random until recently (33), several mechanisms of random breakage have been proposed as causes of BFB.
Also, the targeted mutation of the Terc gene, which encodes the RNA subunit of TERT, results in telomere shortening that, in turn, leads to end-to-end fusions and subsequent chromosome breaks and translocations.
High or dysregulated levels of cyclin E are known to cause mitotic defects such as centrosome amplification and increases in chromosome breaks and translocations (Hinchcliffe et al. 1999; Lacey et al. 1999; Loeb et al. 2005; Bagheri-Yarmand et al. 2010).
Little is specifically known about the effects of Po exposure to the embryo and fetus, however, fetal exposure could cause failure of implantation or miscarriage or major malfunctions (Jefferson et al. 2009), as well an increased incidence of chromosomal breaks and translocations resulting in childhood cancer.
