DNA fragments

DNA fragments from one particular chromosome.
Probes for all 24 human chromosomes
are hybridized to the metaphase. Two approaches
have proved particularly useful: multiplex
fluorescence in situ hybridization (MFISH,
Speicher et al., 1996) and spectral karyotyping
(SKY, Schröck et al., 1996). Other approaches
and modifications exist; for example,
the use of artificially extended DNA or chromatin
fibers. In comparative genome hybridization
(CGH), the quantitative difference in allelic
sequences on homologous chromosomes is
compared to detect deletions or duplications
and amplifications.