Molecular Pathology Laboratory Network

F D20

20q-, deletion 20q12

Acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), myeloproliferative disorder (MPD)

Fluorescence in situ Hybridization (FISH)

88367 x1 - Morphometric analysis, in situ hybridization, automated
88368 x1 - 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

• Whole blood and bone marrow, ship ambient
• Fresh tissue, FNA or paraffin embedded tissue, ship in a Styrofoam container with an ice pack (Do not allow ice pack to directly contact sample)

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

In a normal cell, the expected pattern is the two orange signal pattern. In an abnormal cell containing the deletion, the one orange signal pattern is observed.

Deletions of the long arm of chromosome 20 represent a common chromosomal abnormality associated with myeloid disorders, in particular with myeloproliferative disorders (MPD), myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). The deletion is rarely seen in lymphoid malignancies. Other chromosome changes commonly occurring with deletion 20q are monosomy 5/5q-, monosomy 7/7q-, and trisomy 8. FISH can detect this abnormality in either interphase or metaphase cells.

1. Brezinova Jana et al. (2005). Cancer Genetics and Cytogenetics. 160:188–192.
2. Bilhou-Nabera C. (2000). del(20q) in myeloid malignancies. Atlas Genet Cytogenet Oncol Haematol.
3. Wang PW et al. (1998). Refinement of the commonly deleted segments in myeloid leukemias with del(20q). Gene Chromosomes Cancer. 21(2):75.