Cytogenetics of acute promyelocytic leukaemia: incidence of t(15;17) at the Royal Marsden Hospital, London

New variant Ph translocation in chronic myeloid leukemia: t(Y;22)(p11;q11)

A 4-year-old boy with chronic myeloid leukemia (CML) was shown to have a variant Ph t(Y;22)(p11;q11). To our knowledge, this is the first report of a variant Ph translocation involving Y. Molecular analysis showed that the breakpoint on chromosome 22 is in the breakpoint cluster region (bcr), typical of CML with the classic t(9;22), suggesting that it might be a complex Ph translocation with the involvement of 9q34.

Cytogenetic studies in acute promyelocytic leukemia: a survey of secondary chromosomal abnormalities

A series of 105 patients with acute promyelocytic leukemia (APL) has been cytogenetically investigated at the Department of Hematology of the Saint-Louis Hospital (Paris) between 1977 and 1990. Sixty-two patients were examined at diagnosis, 32 in relapse, and 11 both at diagnosis and in relapse. The typical t(15;17)(q22;q12) or variants of this translocation were observed in all but four patients. The t(15;17) was the only change in 47 cases at diagnosis and in 21 examined in relapse. The most frequent secondary change was trisomy 8 (17% at diagnosis). More or less complex chromosomal abnormalities in addition to t(15;17) were present in six patients at diagnosis, and in 17 patients in relapse. Rearrangements of 2q35-q37 and del(11p) were observed only in relapse and may thus be nonrandom secondary changes. Cytogenetic studies performed on 19 patients treated with all-trans retinoic acid did not indicate that this treatment induces chromosomal abnormalities.

Cytogenetic peculiarities in chronic myelogenous leukemia

Cytogenetic investigations were performed in 185 patients with chronic myelogenous leukemia (CML) at all stages of the disease; 166 patients were Ph positive-159 (95.8%) of these showing the standard Ph translocation, and 7 (4.2%) variant translocations-17 patients were Ph negative. In 2 patients the cytogenetic analysis was unsuccessful. Additional aberrations were found in 40 (24.1%) of the Ph-positive patients. Nine (52.9%) of the Ph-negative patients showed chromosome anomalies. Besides the well known nonrandom abnormalities (-7, +8, i(17q), +19, +Ph) we found a high frequency of clones with rare or not yet described structural rearrangements--in 14 cases (34.2%) of the Ph-positive patients and in 2 cases (20%) of the Ph-negative patients with other chromosome abnormalities. The clinical significance of these findings is discussed.

A new variant translocation 11;17 in a patient with acute promyelocytic leukemia together with t(7;12)

Bone marrow cells from the majority of patients with acute promyelocytic leukemia (APL) are characterized by t(15;17)(q22;q11-12). At least 12 variant translocations have both also reported, and in each case, either abnormal chromosome 15 or del(17q) or both were involved in complex rearrangements. We report a patient with APL showing two translocations without apparent involvement of chromosome 15 and without del(17q). The karyotype was 46,XY,t(7;12)(p15;p13),t(11;17)(q13;q12). Rearrangement involving t(11;17) is probably associated with APL, while t(7;12) appears to be therapy related.

Cytogenetic and clinical studies in acute promyelocytic leukemia (M3) and cytologic M3 variant (M3V)

Cytogenetic specimens were obtained from bone marrow 24-hour cultured cells in 22 patients with acute promyelocytic leukemia, including six with microgranular variant. A t(15;17) was identified in 10-100% of metaphase cells from 13 patients. We have found no correlation between complete remission percentage and karyotype. Our data suggest that each laboratory, as far as M3 and M3V are concerned, must study its own culture time as it relates to numerous parameters involving tumoral cell kinetics.

Incidence of the 15q+;17q- chromosome translocation in acute promyelocytic leukaemia (APL)

Cytogenetic analysis was carried out on peripheral blood cultures from seven patients with acute promyelocytic leukaemia (APL-M3). A reciprocal 15;17 chromosome translocation, t(15q+;17q-), was found in all cases, and the breakpoints estimated to be 15q22 and 17q12-21. In addition to the t(15q+;17q-), trisomy 10 was found in 50% of cells analysed in one case. These results suggest that the 15;17 chromosome translocation may be observed in most cases of APL where the leukaemic cells are cultured before cytogenetic analysis is performed. The use of conditioned media in the culture of leukaemic cells is also described.