Shortened Telomeres Involved in a Case With a Jumping Translocation at
1q21
Shinji Hatakeyama,
Kazuhiro Fujita,
Hiraku Mori,
Mitsuhiro Omine, and
Fuyuki Ishikawa
From the Department of Life Science, Tokyo Institute of Technology,
Yokohama; and the Division of Hematology, Showa University Fujigaoka
Hospital, Yokohama, Japan.
The jumping translocation (JT) is a rare chromosomal abnormality in
which a specific chromosomal segment translocates onto the ends of
various chromosomes (jumps). In most cases, the region distal to 1q21
jumps onto numerous different telomeres. Here we report a molecular
study of the JT involving 1q21 found in a patient with acute
myelomonocytic leukemia that had transformed from myelodysplastic syndrome (MDS). This is the first report describing the analysis of the
molecular structure of the JT. We demonstrated the presence of a
stretch of telomeric repeats at the breakpoint by means of a
fluorescence in situ hybridization experiment, molecular cloning, and
nucleotide sequencing of the fused region. A significant amount of
variant telomeric repeats (a telomeric sequence having one-base mismatch within the authentic telomeric repeat TTAGGG) was found in
this region. The variant telomeric repeat has been shown to be present
in the proximal region of telomeres and does not perform telomeric
functions by itself. Therefore, these results indicated that the
telomeres had already been critically shortened when the jumps
occurred. We suggest that the extended proliferation of cancer cells
during the premalignant stage, such as MDS, results in chromosomal
instability due to the loss of telomeric functions.
Blood, Vol. 91 No. 5 (March 1), 1998:
pp. 1514-1519
© 1998 by The American Society of Hematology.
