The Cytogenetics section performs karyotyping using G-banding and FISH (Fluorescence in situ Hybridisation).
Karyotyping using G-banding is performed on the metaphases of cells cultured from bone marrow aspirate samples or peripheral blood collected in sterile bone marrow transport medium (available from the laboratory) or Lithium Heparin. This identifies chromosomal changes, which can be associated with a wide variety of haematological disorders and can be important for classification of the disease and give a guide to disease prognosis.
FISH identifies specific genetic changes using fluorescently labelled chromosomal probes. FISH can be performed as the primary genetic test e.g. as a screening for recurrent cytogenetic abnormalities in a suspected disease, in diseases that cannot easily be cultured (e.g. CLL), or when cytogenetic culture for karyotype analysis fails, in order to confirm or exclude specific cytogenetic abnormalities e.g. BCR-ABL1 rearrangement in CML. For monitoring minimal residual disease in patients with a previously known FISH-detectable rearrangement FISH can be used if more sensitive techniques such as PCR are not applicable. FISH can be performed on metaphase or interphase cells on cultured blood or bone marrow, and on interphase cells from blood and bone marrow smears, and tissue sections.
Bone marrow aspirate (1-2mL) in bone marrow transport medium containing RPMI medium, heparin and antibiotics (available from the laboratory on request). If unavailable, samples should be placed in lithium heparin. Samples for CLL and Multiple Myeloma FISH should be sent in EDTA. In certain instances FISH may be performed on formalin fixed, paraffin embedded tissue sections. Please call the laboratory to arrange for these to be done, and for further details on sample requirements.
The Cytogenetics report will provide the karyotype of the cell population analysed and/or abnormalities detected by FISH. An overall conclusion and interpretation (including prognostic significance where known) will be given.
Anticipated turnaround time
Urgent FISH results are usually available within 48 hours of sample collection and routine results within 5 days.
Karyotype analysis is a time consuming, labour intensive procedure. Urgent samples (e.g. acute leukaemias; CML) will be processed within 14 working days. Non-urgent samples can be processed within 4 weeks; this may take longer depending on laboratory workload. If a result is required by a specific date, please notify the laboratory.