Practice question

M-FISH uses combinatorial fluorescence strategy where each chromosome is painted with a unique combination of fluorochromes, creating a distinct spectral signature decoded by software. Down syndrome results from trisomy 21. In M-FISH, chromosome 21 probes labeled with a specific fluorochrome combination appear thrice per metaphase spread instead of twice, readily identified by extra same-colored chromosome and automated image analysis. Color-coded fluorophores thus enable rapid whole-karyotype screening without chromosome-specific conventional G-banding expertise. Probe size, RNA tagging, and secondary antibody use are not primary discriminators for aneuploidy detection speed.