Molecular Pathology Laboratory Network

F MDS

EGR1 -5 /5q-, CEP 7 -7/7q-, trisomy 8, del(20)(q12), deletion 20q12

Myelodsyplasia (MDS)

Fluorescence in situ Hybridization (FISH)

88367 x6 – Morphometric analysis, in situ hybridization, automated
88368 x6 – Morphometric analysis, in situ hybridization, manual

3 days

• 2.0 mL (min. 1.0 mL) peripheral blood in sodium heparin preferred, EDTA accepted
• 1.0 mL (min. 0.5 mL) bone marrow in sodium heparin preferred, EDTA accepted
• 5 mm^3 fresh tissue in MPLN RPMI media
• 3.0 mL (min. 2.0 mL) FNA in MPLN RPMI media
• 10% neutral buffered formalin fixed paraffin embedded tissue

• Peripheral blood and bone marrow stable at 18-25°C for 72 hours
• Fresh tissue or FNA stable at 2-8°C for 72 hours

Clotted specimen; Specimens exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells; Improper fixative

See report

Clonal chromosome abnormalities are found at diagnosis in about 60% of patients with de novo MDS and almost 85% of those with AML or secondary MDS. The FISH profile used for detection of chromosome abnormalities in MDS and AML includes probes for chromosomes 5, 7, 8 and 20. Deletion of chromosome 5 is the most common structural abnormality in MDS and AML. The EGR1 probe is localized to 5q31 and detects both deletion of the long arm of 5 and monosomy 5. Similarly, the D7S486 probe, which is located at 7q31, is designed to detect monosomy 7 and deletions of the long arm of 7. The CEP 8 probe detects trisomy 8, the most common numerical abnormality in MDS and AML. Finally, the probe for 20q12 will detect deletions of the long arm of chromosome 20.

Complex karyotypes involving 3 or more of these chromosomes occur in approximately 5% of cases and will also be detected by this profile of probes. Detection of abnormalities involving 5, 7, 8, and 20 are important prognostic indicators in MDS and AML. FISH for these chromosome abnormalities can be performed on interphase or metaphase cells.