M-FISH is most suitable for:
M-FISH generates a comprehensive spectral karyotype where each chromosome pair exhibits a distinct combinatorial fluorescent code. This permits detection of numerical aneuploidies, unbalanced translocations, marker chromosomes, and cryptic rearrangements that underlie inherited syndromes such as Down, Turner, Klinefelter, and microdeletion disorders. Because it interrogates entire genomes at chromosomal resolution rather than single nucleotide changes or protein interactions, it excels for constitutional cytogenetic screening. SNP identification requires sequencing or arrays, while transcript length measurement and protein interaction studies employ entirely different transcriptomic and proteomic platforms.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.