Deletions of the long arm of chromosome 20 represent a common chromosomal abnormality associated with myeloid malignancies, in particular with myeloproliferative disorders (MPD), myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). Using G-banding cytogenetic techniques, we found clones with del(20q) in 36 patients with hematological malignancies examined in our laboratory during the years 2001-2003: in 23 patients as a sole cytogenetic aberration and in 13 patients together with other chromosomal changes. Fluorescence in situ hybridization (FISH) with a probe specific for the 20q12 region was used in all cases to confirm the presence of the clone with deletion. For patients with additional or complex chromosomal rearrangements, multicolor FISH (M-FISH) analysis was performed. Statistical evaluation of the prognostic impact of sex, age, diagnosis, and karyotype was performed. The survival time correlated with the type of chromosomal aberration; no significant differences in survival were found for sex, age, and diagnosis.
"Accordingly, del(20q) as an isolated abnormality must be distinguished from cases of other chromosomal rearrangements for better stratification of prognosis. For de novo AML, isolated del(20q) is known to be associated with poor response to treatment and reduced survival [1, 3]. "
[Show abstract][Hide abstract] ABSTRACT: Prognosis is known to be better in cases with isolated chromosomal abnormalities than in those with complex karyotypes. Accordingly, del(20q) as an isolated abnormality must be distinguished from cases in which it is associated with other chromosomal rearrangements for a better stratification of prognosis. We report a case of an isolated del(20q) abnormality with additional genomic aberrations identified using whole-genome single nucleotide polymorphism array (SNP-A)-based karyotyping. A 39-yr-old man was diagnosed with AML without maturation. Metaphase cytogenetic analysis (MC) revealed del(20)(q11.2) as the isolated abnormality in 100% of metaphase cells analyzed, and FISH analysis using D20S108 confirmed the 20q deletion in 99% of interphase cells. Using FISH, other rearrangements such as BCR/ABL1, RUNX1/RUNX1T1, PML/RARA, CBFB/MYH11, and MLL were found to be negative. SNP-A identified an additional copy neutral loss of heterozygosity (CN-LOH) in the 11q13.1-q25 region. Furthermore, SNP-A allowed for a more precise definition of the breakpoints of the 20q deletion (20q11.22-q13.31). Unexpectedly, the terminal regions showed gain on chromosome 20q. The patient did not achieve complete remission; 8 months later, he died from complications of leukemic cell infiltrations into the central nervous system. This study suggests that a presumably isolated chromosomal abnormality by MC may have additional genomic aberrations, including CN-LOH, which could be associated with a poor prognosis. SNP-A-based karyotyping may be helpful for distinguishing true isolated cases from cases in combination with additional genomic aberrations not detected by MC.
Annals of Laboratory Medicine 11/2012; 32(6):445-9. DOI:10.3343/alm.2012.32.6.445 · 1.48 Impact Factor
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