FISH - MDS In-Situ

Function

Fluorescence In Situ Hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only those parts of a nucleic acid sequence with a high degree of sequence complementarity. In the context of Myelodysplastic Syndromes (MDS), FISH is used to detect specific chromosomal abnormalities.

Why it is Ordered

MDS is a group of cancers in which immature blood cells in the bone marrow do not mature or become healthy blood cells. FISH is ordered to identify chromosomal deletions, trisomies, or translocations that are characteristic of MDS. This helps in confirming the diagnosis, determining the specific subtype of MDS, and assessing the prognosis.

Common Abnormalities Detected

• del(5q): Often associated with a better prognosis and response to specific drugs like lenalidomide.
• del(7q) / -7: Associated with a poorer prognosis.
• Trisomy 8 (+8): A common but non-specific abnormality.
• del(20q): Generally carries a favorable prognosis.

Clinical Impact

The results of FISH are integral to the International Prognostic Scoring System (IPSS-R) for MDS, which clinicians use to decide on the aggressiveness of the treatment, ranging from 'watch and wait' to stem cell transplantation.