EGR1 -5 /5q-, -7/7q-, +8, 20q-
Fluorescence in situ Hybridization (FISH)
5p15.31 (D5S630,D5S2064)/5q31.2 (EGR1)
7q22 (D7S796,D7S658)/7q31.2 (D7S486)
CEP8 (D8Z2)/8q12.1-q12.2 (CHD7)
20q12 (D20S108)/20q13.12 (D20S43,D20S150)
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
Whole blood and bone marrow, ship ambient
Clotted specimen; Specimens exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells;
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.