Summary. Between 1986 and 2001, 220 patients with polycythaemia vera (PV) were studied using conventional cytogenetics. Of 204 evaluable patients, 52 (25AE4%) had clonal abnormalities. The recurrent chromosomal rearrangements were those of chromosome 9 (21AE1%), del(20q) (19AE2%), trisomy 8 (19AE2%), rearrangements of 13q (13AE4%), abnormalities of 1q (11AE5%), and of chromosomes 5 and 7 (9AE6%). Subsequent analysis of 32 patients, performed at follow-up of up to 14AE8 years, revealed new clonal abnormalities in five patients and the disappearance of an abnormal clone in four. Eleven patients remained normal up to 11AE5 years and seven patients maintained an abnormality for over 10 years. Fifty-three patients were studied retrospectively using interphase fluorescence in situ hybridization (I-FISH), utilizing probes for centromere enumeration of chromosomes 8 and 9, and for 13q14 and 20q12 loci. Conventional cytogenetics demonstrated clonal chromosome abnormalities in 23% of these 53 patients. The addition of I-FISH increased the detection of abnormalities to 29% and permitted clarification of chromosome 9 rearrangements in an additional 5AE6% of patients. FISH uncovered rearrangements of chromosome 9 in 53% of patients with an abnormal FISH pattern, which represented the most frequent genomic alteration in this series.

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Transient donor cell derived myelodysplastic syndrome with monosomy 7 after unrelated cord blood transplantation. European Journal of Haematology, 77, 259-263.

Variants of the t(15;17)(q22;q12-q21) chromosomal rearrangement associated with acute promyelocytic leukemia (APL) have been previously described and they frequently involve either chromosome 15 and/or 17. Previously we reported a rare variant t(11;17). We now describe two patients with myelodysplastic syndrome (MDS) that transformed to APL-like leukemia. Both had trisomy 11 at the diagnosis of APL-like leukemia. Following treatment for APL, patient 1 reverted to MDS and showed a normal karyotype. When leukemia recurred, his bone marrow karyotype was 47,XY,t(4;11), +11,der(22)t(1;22). Both patients were treated with all-trans retinoic acid (ATRA) for APL for 5 weeks, but failed to respond. The karyotype of patient 1 after ATRA treatment was 46,XY,t(4;11); the trisomy 11 had been lost and the bone marrow was replaced with immature myeloblasts without promyelocytes. In patient 2, the karyotype remained the same as at diagnosis, i.e., 47,X,-Y,dir ins(4;7),del(5), +6,del(7), +8, + 11,-18. Molecular analysis by reverse transcriptase PCR analysis showed the presence of wild type retinoic acid receptor alpha (RARA) and the absence of the PML-RARA chimeric gene associated with t(15;17). Additional analysis of PLZF, a new zinc finger gene associated with t(11;17), also showed the absence of this hybrid gene. These data support the concept that APL is a heterogeneous disorder and that variants with chromosome 11 rearrangement exist that do not respond to ATRA.

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