INTERPHASE FLUORESCENCE IN SITU HYBRIDIZATION TEST FOR HAEMATOLOGICAL MALIGNANCIES

​Refer to Table 1. 

1. A Dual Colour Dual Fusion translocation probe detects the juxtaposition of one gene locus with its translocation gene partner. The translocation event produces a fusion of the two genes on the derivative chromosomes.
2. A Dual Colour Breakapart (BA) probe detects disruptions to gene sequences that are known to be involved in translocations with another partner or disruptions due to other rearrangements such as an inversion.
3. A Single Colour Enumeration probe comprises a locus specific identifier probe or centromeric enumeration probe and detects interstitial deletions or loss/gain of a whole chromosome.

​Blood or Bone marrow in sodium/lithium heparin

​Fluorescence In Situ Hybridization using direct-labelled FISH DNA probes and analysed under fluorescence microscopy.

​Normal or Abnormal signal pattern depending on the probe construction:

1. Dual Fusion probe: Typical abnormal signal pattern is 2 fusions, 1 red and 1 green pattern. Variant pattern is outside the normal range. 
2. Breakapart probe: Typical abnormal signal pattern is 1 fusion, 1 red and 1 green pattern. Variant pattern is outside the normal range.
3. Enumeration probe: Loss or Gain of FISH signal.

FISH findings are reported in accordance to the International System for Human Cytogenomic Nomenclature (ISCN, 2024).

​3 ~ 10 days

​Monday – Saturday (office hours)

​Interphase FISH test may be requested in conjunction with conventional cytogenetic studies (FISH ADD-ON) or as a standalone test (FISH) depending on the disease status. The FISH assay should preferably be done on diagnostic cases prior to treatment so as to determine the baseline pattern.