Spectral karyotyping (SKY) is a molecular cytogenetic tool which allows scientists to visualize all chromosomes in a cell at once by using different fluorescent colors. It is a useful tool for studying complex karyotypes, which involve multi-chromosomal rearrangements, e.g., in some tumor cell lines. Contrary to black and white traditional karyotypes, visualization of chromosomal rearrangements with spectral karyotyping is straightforward as one or more colors will show within a single chromosome.

Cell line from a male patient is initially karyotyped (traditional) as a loss of Y chromosome and a deletion of chromosome 18.

Further investigation using spectral karyotyping (SKY) also reveals a translocation between chromosomes Y and 18. Results confirmed by genome-wide SNP array (not shown). [45,X,-Y,der(18)t(Y:18)(p11;q21.31)]