Excision and then reinsertion or attachment of DNA, only in the opposite orientation.
Chromosomal inversions are a consequence of breakage and then subsequent repair of DNA, only with repair occurring with the DNA inadvertently in reverse. Alternatively, inversion can be a consequence of recombinational errors involving sequence similarity at either end of the to-be-inverted gene.
Inversions can result in errors during meiosis due to inappropriate crossing over between homologues. Nevertheless, inversions more or less by definition do not involve a loss of DNA and therefore, unless a gene has been directly disrupted, do not necessarily result in a loss of organism fitness.
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