Test Directory

20q12/20q13.1

Deletion 20q is seen in a very large spectrum of hematological malignancies such as myelodysplastic syndromes (MDS), acute myeloid leukemias (AML), polycythemia vera, and chronic neutrophilic leukemia. Interstitial or terminal deletion of the long arm of chromosome 20 (20q-) has been described as the second most frequent sole clonal structural abnormality (5 %) behind t(9.22). In MDS, 20q- alone is associated with a good prognosis regarding survival and potential for AML evolution, as defined by the International Prognostic Scoring System (IPSS) for MDS prognosis. In de novo acute leukemia, a poor response to treatment and a reduced survival is observed. In myeloproliferative disorders, the presence of deletion 20q does not appear to adversely affect survival. 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.

Specimen Types: Leukemic Blood or Bone Marrow

Preferred Collection Container: Green Top (Sodium Heparin)

Alternate Collection Container: Lavendar Top (EDTA)

Desired Specimen Volume: 3 - 5 mL

Minimum Acceptable Volume: 1 mL

• Lithium heparin is not acceptable.
• Specimens must be collected in a sterile collection container.

Each specimen must be accompanied by a requisition form, script, electronic order or physician note. Each order must indicate the reason for testing (diagnosis).

• Transport to the laboratory at room temperature.
• Store specimen as whole blood, in original tube, at room temperature and deliver to lab within 24 hours.
• If specimen cannot be delivered within 24 hours, store in refrigerator. Do not freeze specimen.
• Specimens collected on the weekends must be refrigerated upon arrival at HNL Lab Medicine.

• Specimen frozen
• Specimen arriving without any form of patient identification (unlabeled)
• Specimen with attached needles
• Specimen arriving with broken or leaking collection tube
• Unfixed specimen treated with fixative

In a normal cell, the expected signal pattern is two red signals and two green signals. In an abnormal cell containing the deletion, the expected signal patterns are one red signal and two green signals or one red signal and one green signal.

• FISH Deletion 20q
• Del(20q)