Leukemic recombinations involving heterochromatin in myeloproliferative disorders with t(1;9).
The unbalanced t(1;9) is a rare, recurrent rearrangement in polycythemia vera (PV) resulting in trisomy of both 1q and 9p arms, whereas a balanced t(1;9)(q12;q12), to our knowledge, has never been reported before. We studied two patients with PV and one with idiopathic myelofibrosis bearing an unbalanced t(1;9) and one patient with essential thrombocythemia with a balanced t(1;9). In all cases fluorescence in situ hybridization showed that the breakpoints were located within the satellite II family of heterochromatin of chromosome 1 and the satellite III of chromosome 9. Heterochromatin breakage and reunion produce the unbalanced t(1;9) and may contribute to a gene dosage effect due to gains of 1q and 9p. Case 4 with the balanced t(1;9), however, suggests that translocation of heterochromatin close to critical genes could interfere with their function. The molecular event underlying juxtaposition of satellite II of chromosome 1 and the satellite III of chromosome 9 remains to be elucidated.
Sambani
Constantina
C
Laboratory of Health Physics & Environmental Hygiene, NCSR Demokritos, 15310 Aghia Paraskevi, Athens, Greece. csambani@ipta.demokritos.gr
La Starza
Roberta
R
Pierini
Valentina
V
Vandenberghe
Peter
P
Gonzales-Aguilera
Juan J
JJ
Rigana
Helen
H
Koumbi
Daphne
D
Manola
Kalliopi N
KN
Stavropoulou
Chryssa
C
Georgakakos
Vasileios N
VN
Pagoni
Maria
M
Wlodarska
Iwona
I
Mecucci
Cristina
C
D000368:Aged; D002878:Chromosomes, Human, Pair 1; D002899:Chromosomes, Human, Pair 9; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D009196:Myeloproliferative Disorders / Q000235:genetics*; D014178:Translocation, Genetic