Reverse painting highlights the origin of chromosome aberrations.

Reverse chromosome painting, as the opposite of forward chromosome painting, means that an abnormal chromosome of interest is recovered by flow sorting or by chromosome microdissection, amplified and labelled by DOP-PCR and hybridized onto normal metaphases of optimal quality. This provides rapid and unequivocal information about the chromosomal origin on the aberrant chromosome in one hybridization. Not only will the specific chromosome(s) involved be identified, but also the subchromosomal origin, including the breakpoints. The method has been used for over 10 years and has proven to be very useful for resolving complex chromosome rearrangements in a variety of different applications, both as a research tool and for clinical purposes in pre- and postnatal diagnosis.