The extent to which all four mutational mechanisms contribute to CNV formation is highlighted in recent findings from the 1000 genomes project (Mills et al., 2011). Approximately 70.8% of the deletions were attributed to either a non homology based mechanism (i.e., NHEJ) or MMBIR. 89.6% of small insertions were attributable to retrotransposition activity. Most tandem duplications displayed microhomology of 2–17 basepairs at breakpoints, indicating that they are likely formed by FoSTeS/MMBIR. Large deletions or duplications showed extensive stretches of sequence of >95% identity at breakpoints, suggesting that they were generated by NAHR.
