Genomic Gain at 6P21: a New Cryptic Molecular Rearrangement in Secondary Myelodysplastic Syndrome and Acute Myeloid Leukemia

Genomic gain at 6p21: a new cryptic molecular rearrangement in secondary myelodysplastic syndrome and acute myeloid leukemia

R La Starza1, A Aventin2, C Matteucci1, B Crescenzi1, S Romoli1, N Testoni3, V Pierini1, S Ciolli4, C Sambani5, A Locasciulli6, E Di Bona7, M Lafage-Pochitaloff8, MF Martelli1, P Marynen9 and C Mecucci1

1Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy; 2Servei de Hematologia, Hospital De La Santa Creu I Sant Pau, Barcelona, Spain; 3‘Istituto Seragnoli’, Hospital S Orsola, Bologna, Italy; 4Hematology Unit, University of Firenze, Firenze, Italy; 5Laboratory of Health Physics and Environmental Hygiene, NCSR ‘Demokritos’, Athens, Greece; 6Hematology, Hospital ‘S Camillo’ of Rome, Rome, Italy; 7Hematology, Hospital ‘S Bortolo’ Vicenza, Vicenza, Italy; 8Laboratoire de Biopathologie, Institut Paoli-Calmettes, INSERM U119, Marseille, France and 9Center for Human Genetics and Flanders Interuniversity Institute for Biotechnology (VIB), University of Leuven, Campus Gasthuisberg, Leuven, Belgium

Fluorescence in situ hybridization and comparative genomic ter aberrantly activates the cyclin D3, which is overexpressed;5,6 hybridization characterized 6p rearrangements in eight primary in MM with t(6;14)(p25;q32), the IgH gene juxtaposes to MUM/ and in 10 secondary myeloid disorders (including one patient IRF4.7 with Fanconi anemia) and found different molecular lesions in In secondary myelodysplastic syndrome (MDS) and AML, 6p each group. In primary disorders, 6p abnormalities, isolated in six patients, were highly heterogeneous with different break- rearrangements account for less than 2% of cytogenetic 8 points along the 6p arm. Reciprocal translocations were found abnormalities. Although mainly found in complex karyotypes, in seven. In the 10 patients with secondary acute myeloid which also bear À5/del(5)(q) and/or À7/del(7)(q), rare cases of leukemia/myelodysplastic syndrome (AML/MDS), the short arm isolated 6p rearrangements have been observed.9–11 Deletions, of chromosome 6 was involved in unbalanced translocations in balanced and unbalanced translocations, insertions and dupli- 7. The other three patients showed full or partial trisomy of the cations have been described with a der(1)t(1;6) change as the 6p arm, that is, i(6)(p10) (one patient) and dup(6)(p) (two 12–14 patients). In 5/7 patients with unbalanced translocations, DNA only recurrent abnormality. No specific correlations have sequences were overrepresented at band 6p21 as either cryptic been found with previous exposure because 6p rearrangements duplications (three patients) or cryptic low-copy gains (two have been linked not only to chemo- and/or radiotherapy, but patients). In the eight patients with cytogenetic or cryptic 6p also to different environmental agents.9,10 gains, we identified a common overrepresented region extend- We used a molecular cytogenetic approach to characterize 6p ing for 5–6 megabases from the TNF gene to the ETV-7 gene. 6p rearrangements in primary and secondary myeloid disorders and abnormalities were isolated karyotype changes in four patients. Consequently, in secondary AML/MDS, we hypothesize that 6p found different molecular lesions in each clinical subgroup. gains are major pathogenetic events arising from acquired and/ or congenital genomic instability. Leukemia (2006) 20, 958–964. doi:10.1038/sj.leu.2404208; Patients, materials and methods published online 13 April 2006 Keywords: primary and secondary myeloid malignancies; 6p Patients rearrangements; genomic gain Inclusion criteria were diagnosis of a myeloid disorder, a 6p rearrangement and availability of fixed cells for fluorescence in situ hybridization (FISH) studies. Patients were retrieved from the Departments of Hematology, Universities of Florence, Bologna, Perugia, the ‘S Bortolo’ Hospital in Vicenza, and the Introduction ‘San Camillo’ Hospital in Rome, Italy; the Servei of Hemato- logia, Hospital Sant Pau, Barcelona, Spain; the Health Physics In hematological malignancies, rearrangements at the short arm and Environmental Hygiene Lab, NCSR Demokritos, Athens, of chromosome 6 are characterized by heterogeneous chromo- Greece; the Laboratoire de Biopathologie, Institut Paoli-Calm- some abnormalities, breakpoints and partner chromosomes. In ettes, INSERM U119, Marseille, France. primary disorders, specific clinical–hematological and genetic entities have been identified. In acute myeloid leukemia (AML), Cytogenetics the t(6;9)(p23;q34)/DEK-CAN is associated with bone marrow Bone marrow cells were cultured for 24–48 h. Metaphases were dysplasia and basophilia, a high incidence of FLT3 mutations G-banded with Wright stain, and karyotypes were described and unfavorable prognosis;1,2 in B-cell non-Hodgkin’s lympho- according to the International System for Human Cytogenetic ma (B-NHL), the H4 or SRP20 gene deregulates the BCL-6 Nomenclature.15 oncogene as a result of t(3;6)(q26;p21);3,4 in B-NHL and multiple myeloma (MM) with t(6;14)(p21;q32), the IgH promo- Fluorescence in situ hybridization Correspondence: Professor C Mecucci, Hematology and Bone Marrow Metaphase FISH was performed as described16 with a panel of Transplantation Unit, Policlinico Monteluce, via Brunamonti 51, 6p DNA clones ordered from band p25 to band p12 as shown in 06122 Perugia, Italy. E-mail: [email protected] Table 1. To fully characterize 6p unbalanced translocations, Received 11 October 2005; revised 13 February 2006; accepted 27 whole chromosome painting (WCP) for chromosomes 1, 6, 8, February 2006; published online 13 April 2006 16, 18, 19 and for the short arm of 20, probes for the alpha 6p changes in myeloid disorders R La Starza et al 959 Table 1 Breakpoint restriction in three primaryK and in seven trisomy/splitting (3p14/FHIT 1.5%, 5q33/CSF1R 0.5%, 7q31/ secondary* AML/MDS D7S486 0.5%, 12p13/ETV6 2.5%, 13q14/D13S25 1%, 17p13/ TP53 2%, 21q22/AML1 2.5%) were set at the upper limits Band DNA clones Loci/genes for false positive results as established by our laboratory standard.16,17 Telomere p25 RP3-409kg CHLC.GGAT14C06 p24 RP1-233G22 AFMa272zb5 p23 RP3-511E16 AFMa296zb1 KK Comparative genomic hybridization RP3-366E2 AFM337wg9 KK Comparative genomic hybridization (CGH) was performed as 18 p22 RP1-135L22 WI-5592 already reported. Chromosomal regions were considered RP1-73M23 SSADH * overrepresented if the corresponding green/red ratio exceeded RP3-501N12 WI-4509 1.17 and underrepresented if the ratio was below 0.83. Negative RP1-45P21 StSG2643 control thresholds were established on profiles from hybridiza- p21 RP1-153G14 ZNF184 RP1-15D7 WI-2632 * tion of two differently labeled DNA samples from healthy RP1-97D16 TRMI1 donors. FISH and CGH analyses were carried out using a RP3-408B2O OR2W6P, OR2B6, 0R2W4P * fluorescence microscope (Provis, Olympus, Milan, Italy) RP1-313I6 ZNF165, OR2W2P, equipped with a cooled CCD camera (Sensys, Photometrics) OR2B7P, 0R2B8P run by PathVysion softwares (Vysis, Stuttgart, Germany). RP1-265C24 ZNF435, ZNF192 RP11-424I5 C60RF194 * RP5-874C20 KIAA0426 Results RP5- GPX5 1186N24 RP11-60E24 D6S248 Patients Chromosome6 RP1-111M5 RFP Tables 2 and 3 report, respectively, clinical, hematological and RP1-88J8 HS6M1-15, 0R2W1 * cytogenetic data in 10 patients with secondary and eight with RP5-974I11 HS6M1-6, 0R2U1P primary AML/MDS. cosmid Cah5 TNF RP1-22011 HSET **K RP1-160J11 KNLS2 Cytogenetics RP1-28OE11 StSG28858 K RP1-99J17 HMGA1 In secondary AML/MDS, 6p rearrangements were isolated in RP3-329A5 ZNF76 four cases and included in complex karyotypes in six. The 6p RP1-109F14 FANCE changes included i(6)(p10) (patient 1), 6p duplication (patients 2 RP1-124L9 WI-10190, WI-73111 and 3) and unbalanced translocations (patients 4–10) with RP1-162J16 WI-6620, R12494 diverse chromosome partners or unidentified material (Table 2). RP1-50J22 ETV7 In primary AML/MDS 6p abnormalities were isolated in six RP5-1043E3 StSG22477 RP5-904F15 CBF-A cases, associated with one numerical change in 1 and included RP5-1106P1 CCND3 in complex karyotype in 1. Balanced translocations with diverse RP5-895C5 WI-8795 K chromosome partners were present in patients 11–17. Patient 18 RP3-374I13 RUNX2 had add(6)(p) (Table 3). p12 RP3-381E2 AFM123xe1 K RP4-753D5 TFAP2B Centromere Metaphase fluorescence in situ hybridization and Abbreviations: AML, acute myeloid leukemia; MDS, myelodysplastic multi-color FISH syndrome; TNF, tomor necrosis factor. Secondary acute myeloid leukemia/myelodysplastic syndrome. In patient 1, all 6p probes were present in three copies as expected: one on normal 6 and two on each arm of i(6)(p10) (Figure 1a). In patients 2 and 3 with dup(6)(p), both satellite region of chromosomes 1/5/19 (D1Z7/D5Z2/D19Z3) duplications fell within band p21 and extended, respectively, to and chromosome 6 (D6Z1) were used (Oncor, Appligene include clones RP1-153G14 to RP3-381E2 and cosmid CAH5 to Gaithersburg, MD, USA; Vysis, Stuttgart, Germany; ListarFish, RP4-753D5 (Figure 1b). Breakpoints of 6/7 unbalanced trans- Milan, Italy). Multi-color FISH (M-FISH) experiments with the locations (patients 4–8 and 10) clustered at band p21; the other 24XCyte human multi-color FISH probe kit (MetaSystem, Zeiss, breakpoint in patient 9 was at band p23 (Table 1). Altlussheim, Germany) were performed in patient 8 (Table 2). In patients 4, 6 and 7, with unbalanced translocations, FISH Five to ten abnormal metaphases were evaluated by FISH and showed cryptic duplications of a genomic region contiguous to G-banding in each experiment. the translocation breakpoints, at band p21 (Figure 1c and d). In Eleven patients were investigated by interphase-FISH with patients 5 and 8, a low-copy gain with five copies of DNA RP11-888J3 for FHIT/3p14, cos148B6 and cos179A6 for ETV6/ clones mapping at band p21, was present on der(6) and/or 12p13, RP11-199F11 for TP53/17p13, RP5-1106L7 for AML1/ inserted in other derivative chromosomes (Figure 1e and f). In all 21q22 and with the LSI CSF1R SO/D5S721:D5S23 SG/5q33, LSI cases, the 6p21 gain was narrowed to a 5–6 megabase DNA D7S486 SO/CEP 7 SG/7q31 and LSI D13S25 SO 13q14/D13S25 segment extending from the tumor necrosis factor (TNF) gene (LSI probes by Vysis, Downers Grove, IL, USA). Analysis of 200 (cosmid CAH5 at the telomeric side) to ETV-7 (RP1-50J22 at the nuclei was carried out for each probe. Bone marrow samples centromeric side) (Tables 1 and 4). Patients 9 and 10 showed no from healthy donors were added in each experiment as controls. 6p21 gain. The cutoffs for monosomy/deletion (3p14/FHIT 5%, 5q33/ In patients 5–8 and 10, WCP, centromeric probes and multi- CSF1R 2%, 7q31/D7S486 1.96%, 12p13/ETV6 6%, 13q14/ FISH fully characterized complex karyotypes and classified 6p D13S25 4.3%, 17p13/TP53 4.7%, 21q22/AML1 4.7%) and for changes (Table 2).

Leukemia 6p changes in myeloid disorders R La Starza et al 960 Table 2 Clinical, hematological and cytogenetic features of 10 secondary myeloid disorders

Pts S/A Diagnosis (FAB) Sources of exposure Karyotypes I-FISH studies

1 F/70 RAEB-T CMF, radiotherapy 43,XX,del(5)(q),add(10)(p),À12,add(14)(p),À16,À17[4] ND (breast cancer) 44,XX,add(1)(p36),del(5)(q),i(6)(p10),add(10)(p),À11,À12[6] 2 M/32 RAEB-T Glues, solvents 46,XY,dup(6)(p12p23)[10]/46,XY[10] Normal 3 M/20 RA Fanconi’s anemia 46,XY,dup(6)(p12p21)[15] Normal 4 F/23 AML-M4 Spray paint 46,XX,der(6)t(1;6)(q12;p21)[20] Normal 5 F/78 AML-M1 Insecticides, pesticides 44,XX,À5,der(6)t(6;8)(p21;q13),i(8)(q10),der(17) ND t(5;17)(p13;q11.2), À18[15] i(8)(q10). ish der(8)ins(8;6)(p?;p21)(D6Z1À,WCP6+,WCP8+) 6 M/69 RAEB Spray paint 44,XY,À5,dic(6;19)(p21;p13),del(7)(q),À19[10/20]/46,XY[10] Monoallelic loss dic(6;19)(p21;p13). ish der(19)t(6;19) 5q33/CSF1R (D6Z1-, D1Z7/D5Z2/D19Z3+,WCP6+,WCP19+) 7q31/D7S486 7 M/80 RAEB Chlorambucil (CLL) 45,XY,add(6)(p22),der(12)t(6;12)(p22;p11),À18[21] Monoallelic loss add(6).ish der(6)t(6;19)(p21;?)(WCP6+,WCP19+) 12p13/ETV6 8 M/44 MDS ABVD+auto-BMT (HD) 42–45,XY,add(1)(p36),À3,À5,À6,del(7)(q),der(9)t(6;9) Monoallelic loss (p21;q34),add(12)(p13),add(15)(p),+2À4 markers [cp 10] 3p14/FHIT multi-fish. 42–45,XY,der(1)t(1;6)(p36;?),À3,À5,À6,der(7) 5q33/CSF1R del(7)t(3;7)(?;q?),der(9)t(9;6;?)(q34;p21;?),der(12)t(3;12) 7q31/D7S486 (?;p13),der(15)t(5;15)(p11;p11),+2–4 markers 9 M/70 RARS Insecticides, pesticides 46,XY,der(6)t(2;6)(p13;p23)[9]46,XY[2] Normal 10 M/57 AML-M4 CTX, MX, VCR (NHL) 42,XY,add(6),À7,À16,À18,add(19)(p13),À20[2] ND 42,XY,add(3)(q29),+iso(3)(p),add(6),À16,À18,add(19)(p13),À20[20] 46,XY[4] add(6).ish der(6)t(6;20)(p21;p11)(D6Z1+,WCP6+, CAP20+) Abbreviations: A, age; ABVD, doxorubicin, bleomycin, dacarbazine, vinblastine; AML, acute myeloid leukemia; auto-BMT, autologous bone marrow transplantation; CLL, chronic lymphocytic leukemia; CMF, cyclophosphamide, metotrexate, fluorouracil; CTX, cyclophosphamide; F, female; FAB, French–American–British classification; HD, Hodgkin’s disease; M, male; MDS, myelodysplastic syndrome; MX, mitoxantrone; NHL, non-Hodgkin’s lymphoma; Pts, patients, RA, refractory anemia;RAEB, refractory anemia with excess of blasts; RAEB-T, refractory anemia with excess of blasts in transformation; S, sex; RARS, refractory anemia with ringed sideroblasts; VCR, vincristine; I-FISH studies were carried out with a panel of DNA clones for 3p14/FHIT, 5q33/CSF1R, 7q31/D7S486, 12p13/ETV6, 13q14/D13S25, 17p13/TP53 and 21q22/AML1; normal indicates that all DNA clones gave a normal hybridization pattern (see Results section for details); ND, not done.

Table 3 Clinical, hematological and cytogenetic features of eight primary myeloid disorders

Pts S/A Diagnosis (FAB) Karyotypes I-FISH studies

11 M/33 AML-M2 46,XY,t(2;6)(q22;p23)[10] ND 46,XY,t(2;6)(q22;p23),t(7;12)(p11;p13)[5] 12 M/61 AML 46,XY,t(2;6)(p11;p21)[17] Normal 46,XY,t(2;6)(p11;p21),del(15)(q22)[3] 13 M/61 AML-M2 46,XY,t(4;6)(q21;p23)[20] Normal 14 F/72 AML 46,XX,t(6;12)(p21;p13)[10] Splitting 73,XX,complex[10] 12p13/ETV6 15 M/31 AML-M3 47,XY,der(4)t(4;?)(q21;?),der(6)t(6;?)(p21;?),+8,del(13)(q14),der(15)(q), ND der(17)t(4;17) (q21;q12)[20] 16 M/35 RAEB 46,XY,t(6;16)(p23;p13)[15] ND 46,XY[7] 17 M/86 AML-M2 47,XY,t(6;17)(p21;p13),+11[20] Normal 18 M/74 AML 46,XY,add(6)(p23)[13] ND 46,XY[2] Abbreviations: A, age; AML, acute myeloid leukemia; CML, chronic myeloid leukemia; F, female; FAB, French–American–British classiﬁcation; M, male; Pts, patients; RAEB, refractory anemia with excess of blasts; S, sex; I-FISH studies were carried out with a panel of DNA clones for: 3p14/ FHIT, 5q33/CSF1R, 7q31/D7S486, 12p13/ETV6, 13q14/D13S25, 17p13/TP53 and 21q22/AML1; normal indicates that all DNA clones gave a normal hybridization pattern (see Results section for details); ND, not done.

Primary acute myeloid leukemia/myelodysplastic syn- 5q33/CSF1R, and 7q31/D7S486, in patient 8, with one signal in drome. 6p breakpoints were mapped at bands p24–p23 in 40–90% of nuclei, was in accord with the karyotype showing four cases and at band p21 in the other four (Table 1). partial or full loss of the corresponding chromosomes (Table 2). In patient 14, probes for 12p13/ETV6 gave split signals in 50% of nuclei indicating its involvement in t(6;12)(p21;p13), which was Interphase ﬂuorescence in situ hybridization further demonstrated by metaphase FISH (data not shown). No This study was performed in patients 2–4 and 6–9 (Table 2) with cryptic genomic rearrangements were found in the other patients. secondary and in patients 12–14 and 17 (Table 3) with primary AML/MDS. In patient 7, probes for 12p13/ETV6 were mono- somic in 92% of nuclei, concurring with the presence of an Comparative genomic hybridization unbalanced 12p translocation. Monoallelic loss of probes for Comparative genomic hybridization was performed in patients 5q33/CSF1R and 7q31/D7S486, in patient 6, and for 3p14/FHIT, 1 and 8. In patient 1, CGH detected gains of chromosome

Leukemia 6p changes in myeloid disorders R La Starza et al 961

Figure 1 Double-color ﬂuorescence in situ hybridization in patients 1, 2, 5, 6, 7 and 8 with secondary acute myeloid leukemia/myelodysplastic syndrome using DNA clones RP1-22O11 (red signals) and RP1-50J22 (green signals) showed three or ﬁve red/green fusion signals. In all cases, one red/green signal is present on normal 6 (arrow): (a) patient 1: one fusion signal on each arm of i(6)(q10) (arrowhead); (b) patient 2: two fusion signals on dup(6)(p12p23) (arrowhead); (c) patient 6: two fusion signals on der(19)t(6;19) (arrowhead); (d) patient 7: two fusion signals on der(6)t(6;19) (arrowhead); (e) patient 5: three fusion signals on der(6)t(6;8) and one on a marker chromosome (arrowheads); (f) patient 8: four signals were inserted within diverse derivative chromosomes (arrowheads).

1 at bands 1p31–p32 and 1p36, a gain of the entire short arm secondary AML/MDS. Primary AML/MDS showed a low of chromosome 6 and losses of the 5q11–q23 region, the incidence of complex karyotypes and a high incidence of 12q21 band, the long arm of chromosome 16 and the 22q13 reciprocal translocations, conﬁrming other observations.19 In band. In patient 8, we observed gains of the short arm of secondary AML/MDS, complex karyotypes in 60% of patients chromosome 5 and band 6p21, and losses of chromosome 3 in included at least one numerical or structural aberration that is the 3p11–p21 and 3q11–q23 regions, 5q13.3–qter, 6p24–pter typically associated with therapy-related AML/MDS (À5/5qÀ in and 7q31–qter. four patients, À7/7qÀ in three, monosomy 18 in three) (Table 2). The short arm of chromosome 6 was involved in unbalanced translocations in 7/10 patients. In the other three, the 6p arm Discussion gains included full or partial trisomy, that is, i(6)(p10) (patient 1) and dup(6)(p) (patients 2 and 3). In patients 4–9 with unbalanced Cytogenetic and molecular ﬁndings indicate two distinct translocations, DNA sequences were overrepresented at band genotypes underlying 6p rearrangements in primary and 6p21 as either cryptic duplications or cryptic low-copy gains

Leukemia 6p changes in myeloid disorders R La Starza et al 962 Table 4 6p gains in eight sAML/MDS. (each black line indicates the overrepresented region. Patient number as in Table 2

(Figure 1). Gains varied in size; the smallest common over- tion–recombinations in secondary AML/MDS might mirror represented region extended for 5–6 megabases. congenital events. As duplications/low-copy gains occurred in secondary AML Duplicons, which localize in multiple regions of the human and in the Fanconi anemia (FA) patient, external toxic insults genome, appear to mediate homologous recombinations which and congenital instability appear to share the same genetic may change chromosome structure.25 In acquired transloca- pathway. In fact no association emerged with specific toxic tions, one example is the 76 kb identical duplicon at both 9q34 agents, as both environmental/professional exposure and and 22q11 breakpoints in t(9;22)(q34;q11).26 chemo-/radiotherapy were documented in all our patients: three Olfactory receptor (OR) gene clusters are duplicons dispersed had undergone chemotherapy, one chemo- and radiotherapy, throughout the genome, which mediate chromosomal rearran- two were farmers exposed to pesticides and insecticides, two gements in congenital syndromes.27,28 In our patients five OR were spray painters, one was a plumber exposed to solvents and clusters are located close to or within the 6p21 common glues. The patient with FA had congenital chromosomal overrepresented region. Their genomic instability could account instability.20 for the intra-chromosomal (duplications and amplifications) and Here, we demonstrate for the first time that a gain of a 5–6 inter-chromosomal recombinations (translocations). Whether megabases genomic segment at 6p21 is recurrent and underlies toxic insults or congenital defects of DNA repair worsen the heterogeneous chromosomal changes. Cytogenetically, amplifi- genomic instability at 6p21 needs to be investigated. cations are frequently associated with double minutes or Whatever the mechanism, 6p gains impact on the onset and homogenously staining regions.21,22 which were never observed development of many tumors such as NHL, osteosarcoma, lung, in our series. We found cryptic 6p gains at the translocation breast and ovarian carcinoma, retinoblastoma and uveal breakpoints of der(6) in cases with duplications and/or within melanoma.29–35 In the U937-I cell line, with its unbalanced derivative chromosome partners in cases with low-copy gains. 6p translocation at karyotype,18 we detected a cryptic 6p21 As genomic duplications occur at breakpoints of abnormal duplication/amplification spanning the DNA segment from the chromosomes in several genetic disorders,23,24 the 6p duplica- BAK/6p21 gene to RUNX2/6p21, which is partially overlapping

Leukemia 6p changes in myeloid disorders R La Starza et al 963 with the common overrepresented region in the present series translocations to immunoglobulin loci in multiple myeloma. Blood of secondary AML/MDS. Interestingly, array CGH found a 2001; 98: 217–223. 6p21–22 gain in two relapsed AML with unbalanced 6p 7 Iida S, Rao PH, Butler M, Corradini P, Boccadoro M, Klein B et al. translocations.36 Deregulation of MUM/IRF4 by chromosomal translocation in multiple myeloma. Nat Genet 1997; 17: 226–230. Putative candidate genes in the leukemogenic pathway of 8 Johansson B, Mertens F, Heim S, Kristoffersson U, Mitelman F. secondary AML/MDS with 6p21 gains include the MHC Cytogeentics of secondary myelodysplasia (sMDS) and acute complex, NOTCH-4, BAK, FANCE, ETV-7, HMGIY and nonlymphocytic leukemia (sANLL). Eur J Haematol 1991; 47: 17–27. FKBP51. It is worth noting that the HMGIY protein is over- 9 Mecucci C, Michaux J-L, Louwagie A, Boogaerts M, Van Den expressed in uterine leiomyomata with complex rearrangements Berghe H. The short arm of chromosome 6 is nonrandomly involving the 6p arm,37 whereas FKBP51 is overexpressed in rearranged in secondary myelodysplastic syndromes. Cancer Genet Cytogenet 1988; 31: 147–155. megakaryocytes derived from CD34 þ cells of patients with 10 Huret JL, Schoenwald M, Brizard A, Guilhot F, Vilmer E, Tanzer J. 38 idiopathic myelofibrosis. Chromosome 6p rearrangements appear to be secondary changes In our patients, 6p gains sometimes occur as isolated in various haematological malignancies. Leukemia Res 1989; 13: karyotypic changes. They are never associated with cryptic 819–824. genomic rearrangements of putative suppressor/oncogenes, 11 Mancini M, Mecucci C, Cedrone M, Rondinelli MB, Aloe-Spiriti A, which are known to be involved in therapy-related AML/MDS Alimena G. Unbalanced 6p translocation as primary karyotipic anomaly in secondary acute nonlymphocytic leukemia. Cancer or with TP53 deletions such as are observed in secondary AML/ Genet Cytogenet 1992; 60: 93–95. 39,40 MDS with MLL and AML1 duplications/amplifications. 12 Jacob AK, Sreekantaiah C, Baer MR, Sandberg AA. Translocation Consequently, we hypothesize that 6p gains are major (1;6)(p12;p23) in ANLL. Cancer Genet Cytogenet 1990; 45: pathogenetic events arising from acquired and/or congenital 67–71. genomic instability. 13 Michalova` K, Lemez P, Bartsch O, Brezinova J, Zemanova Z, Jelinek J et al. Derivative (6)t(1;6)(q22;p21) revealed in bone marrow cells by FISH 9 months before diagnosis of acute Acknowledgements T-lymphoblastic leukemia. Cancer Genet Cytogenet 1996; 86: 131–135. 14 Mathew S, Head D, Rodriguez-Galindo C, Raimondi S. Trisomy of PAC and BAC clones were obtained from the Roswell Park Cancer the long arm of chromosome 1 resulting in a dicentric derivative Institute libraries RPCI-1, RPCI-3, RPCI-5 and RPCI-11, http:// (6)t(1;6) chromosome in a child with myelodysplastic syndrome www.chori.org/BACPAC. RP5-1106L7 was kindly provided by Dr following treatment for a primitive neuroectodermal tumor. M Rocchi, University of Bari, Italy; cosmid Cah5 by Dr E Weiss, Leukemia Lymphoma 2000; 37: 213–218. Ludwig Maximilians Universita¨t, Mu¨nchen, Germany; and clones 15 Mitelman F (ed) An International System for Human Cytogenetic RP1-22O11, RP1-99J17, RP1-162J16, RP1-124L9 and RP3-329A5 Nomenclature (ISCN). Basel: S Karger, 1995. 16 Crescenzi B, La Starza R, Romoli S, Beacci D, Matteucci C, Barba by Dr I Ragoussis King’s College, London, UK. We thank Dr G et al. Submicroscopic deletions in 5qÀ associated malignancies. Geraldine Anne Boyd for assistance in preparing the manuscript. 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