Test BackgroundFISH involves the application of fluorescent DNA probes specific to genes or genetic regions of interest that highlight abnormalities involving these regions.
Conventional cytogenetic analysis is carried out routinely on diagnostic T-ALL samples. If a normal karyotype is found, further FISH is applied using a panel of probes for common recurrent abnormalities in this disease, comprising:
Sample Required See notes section
Sample Volume Samples would not be rejected on the basis of small volume, however, 5 mL is ideal.
Turnaround Time • Urgent referrals (at diagnosis)- 95% should be reported within 10 calendar days.• Rapid test by FISH 95% should be reported within 3 working days. • Routine referrals (follow-up) 95% should be reported within 21 calendar days.
Bone marrow in cytogenetic transport medium (preferred) or lithium heparin is usually the sample of choice, but peripheral blood in lithium heparin may be suitable if there are circulating blasts and/or a high white blood cell count. EDTA samples are only suitable in cases requiring FISH only (eg follow-up samples from patients with FISH-detectable abnormalities). If in doubt please use lithium heparin. Samples which are non-sterile, clotted or collected in sodium citrate, fixative or saline are not suitable.
To ensure appropriate analysis and interpretation it is important to provide clear and concise clinical information.