Acquired Robertsonian translocations in hematologic malignancy

Pathogenetic insight and prognostic information from standard and molecular cytogenetic studies in the BCR-ABL-negative myeloproliferative neoplasms (MPNs)

“…143 In total eight cases have been reported, of which six underwent leukaemic and one a myelofibrotic transformation. [144][145][146][147][148] Similar findings have been reported for der(1)t(1;9) in PV and PMF 149 and for t(6;10)(q27;q11) in PMF. 150 Structural abnormalities of the long arm of chromosome 12, non-random findings in myelofibrosis, confers a poor prognosis because of early blast transformation, 151 whereas Strasser-Weipel et al 152 reported the poor prognosis of chromosome 7 deletions (À7/7qÀ), although somewhat surprisingly this was not related to leukaemic transformation.…”

Acute Myelogeneous Leukemia (M5a) that Demonstrated Chromosomal Abnormality of Robertsonian 13;21 Translocation at Onset

“…However, this phenomenon is postulated to be a mechanism for producing partial trisomy or tetrasomy, contributing to clonal evolution by increasing gene dosage (9). Though fourteen of sixteen cases in the literature revealed numerous additional chromosomal abnormalities other than Robertsonian translocation, no other additional chromosomal abnormalities were observed in the present case at the onset and the same Robertsonian translocation alone in the blood cells was observed at the relapse.…”

Robertsonian translocation as an acquired karyotypic abnormality in leukaemia

“…The two remaining cases reveal G;G translocation in the form of t(21;21). However, as pointed out by the authors (Horsman & Kalousek, 1990), a homologous acquired Robertsonian translocation of the G;G type can be morphologically indistinguishable from an acrocentric isochromosome, especially in the presence of normal chromosome 21. The reason for the rarity of acquired Robertsonian translocations in leukaemia remains uncertain, but may suggest that chromosomal recombinations leading to Robertsonian translocations probably occur more frequently in meiosis than in mitosis.…”

“…There are three possible mechanisms for formation: fusion at the centromere, union following breakage in one short arm and one long arm, and union following breakage in both short arms (Guichaoua et al, 1986). Although it is conceivable that Robertsonian translocations may occur in leukaemia, a review of the literature has identified only eight previously reported cases of acquired Robertsonian translocations (Levitt et al, 1978;Mitelman et al, 1981;Morgan et al, 1987;Fan et al, 1988;Horsman & Kalousek, 1990;Ino et al, 1994) (Table I), making it a rare phenomenon in leukaemia. The Robertsonian translocation occurs as a sole karyotypic abnormality in our patient.…”

“…The reason for the rarity of acquired Robertsonian translocations in leukaemia remains uncertain, but may suggest that chromosomal recombinations leading to Robertsonian translocations probably occur more frequently in meiosis than in mitosis. How acquired Robertsonian translocations contribute to leukaemogenesis remains unclear, although they have been postulated as a mechanism for producing partial trisomy or tetrasomy and thus contribute to clonal evolution by increasing gene dosage (Horsman & Kalousek, 1990). This is analogous to numerical aberrations, for example trisomy 8.…”