Rearrangements of all sizes in genomes, genes and exons can result from a glitch in DNA copying that occurs when the process stalls at a critical point and then shifts to a different genetic template, duplicating and even triplicating genes or just shuffling or deleting part of the code within them, said researchers from Baylor College of Medicine in a recent report in the journal Nature Genetics. The report further elucidated the effect of the fork stalling and template switching mechanism involved in some forms of copy number variation.