Study On The Common Deleted Regions And The Clinical Significances Of Del(20q) In Hematologic Malignancies

Objectives:1.To analyse systematically the clinical and laboratorial characteristics of257hematological malignancy patients with20q-abnormality who received conventionalcytogenetics (CC) analysis in our laboratory from2001to2011and to reveal the uniqueclinical,cytogenetic and prognostic features of these patients in our area.2.To investigatewhether the i(20q-) harbors unique morphological features of the bone marrow cells andprognostic features.3.To analyse if there have significant differences in deletedregions,common deleted regions and amplified regions between different hematologicalmalignancies with20q-abnormality,so as to provide certain information to the analysis oftumor genes within these abnormal DNA copy number regions.4.To understand the clinicaland laboratorial characteristics of hematological malignancy patients with t(20;21)(q11;q11)abnormality which derived from20q-.Methods:1.257cases were studied by R-band karyotypic analysis using direct method and/orshort-term culture for chromosomes preparation.The20q11/12double color FISH probewas used to detect the chromosome abnormalities of the196cases which have thechromosomes reserved.All patients were classified according to the FAB proposals,ofwhich109cases were followed up to take the Kaplan-Meier survival analysis.2.The panelFISH probes,including20q12and20qter were used to detected the abnormality of i(20q-),a retrospective analysis about dysplasias of bone marrow cells was taken between thei(20q-),the isolate20q-,and the20q-accompanied by other chromosomal abnormalitieswho have the bone marrow slides reserved,survile analysis was performed between thethree groups.3.21cases whose cell samples were reserved were sended to ShangHai Biocorporation to take the whole genomic aCGH analysis,ues the normal bone marrow as the experimental control.4.The panel FISH probes,including20q11/12，SE20，SE21，20qter，21qter，WC20，and WC21were used to detected the abnormalities of t(20;12).Results:1.The clinical and cytogenetic features of257cases of hematologic malignancieswith20q-abnormalities257patients(163males/94females) with20q-abnormalty were registered in thisstudy,the ages were mainly in50-59years and60-69years.They suffered from:MPN(n=13)(5.1%),MDS(n=127)(49.4%),AML(n=45)(17.5%),CML(n=5)(2.0%),ALL(n=15)(5.8%),AL(n=6)(2.3%),Eosinophilicsyndrome(n=2)(0.8%),CLL(n=2)(0.8%),MH(n=1)(0.4%),macroglobulinemia(n=1)(0.4%),diagnostic unknown(n=40)(15.6%).CC analyses was performed on all257patients,of which,120patients(46.7%) wereisolate20q-,32patients(12.5%) were20q-accompanied by another one chromosomeabnormalities,72patients(28.0%) were complicated abnormalities with20q-,28patients(10.9%) were i(20q-),5patients(1.9%) were duplication of20q-. The male was domination,no significant differences between the groups were found for ages,median WBC counts,Hb level, PLT counts（P＞0.05）.In the group of20q-accompanied by other chromosomeabnormalities,the other23chromosomes were all involved,the abnormalities ofchromosome5were most frequent(41%),and then the chromosome7(40%) andchromosome9(39.7%) followed.In the FISH analysis of the196patients,there were almosthalf of the patients whose signal was1G1R,demonstrate that both20q11and20q12weredeleted,and there were half the patients whose positive cell percentages were extend50%,as the clone groups are large.As the survival analysis illustrated,the median survivalwas46months for the isolate20q-group,longer than the20q-accompanied by otherchromosome abnormalities group whose median survival was11months（P=0.00）.andlonger than the20q-accompanied with one chromosome abnormalities whose mediansurvival was14months （P=0.001）.No significant differences between the20q-accompanied with one chromosome abnormalities group and20q-complicated group.Themedian survival of20q-with complicated numeral and structural chromosomeabnormalities was11months,which longer than the complicated20q-with isolate structural abnormalities whose median survival was4months（P＜0.05）.The mediansurvival of small clones was longer than the large clones of20q-（P＜0.05）. No significantdifferences between2G1R signal group and1G1R signal group in median survival.2.The morphological and prognostic studies of idic(20q-)28patients(17males/11females) with i(20q-) abnormalty were registered in ourstudy,accounting for10.9%of the20q-patients from2001to2011.The incidences ofhypogranulated and vacuolized neutrophils, hypogranular and vacuolized eosinophils,neutrophil erythrophagocytosis, deeply lobulated and hyperlobulated megakaryocytes inbone marrow cells was higer in i(20q-) group than in isolate20q-group(P＜0.05). Nosignificant differences between i(20q-) group and20q-accompanied by other chromosomeabnormalities group in frequency of hypogranulated and vacuolized neutrophils,theincidences of other three type of morphological changes were higher in i(20q-) group（P＜0.05）. No significant differences between the three groups in frequency of the othererythroid or myeloid morphological changes, the incidences of nuclear fragmentation,megaloblastic change, vacuolized changes and hypogranulated changes in i(20q-) groupwere higher than in other two groups. In megakaryocyte,the incidence of smallmegakaryocyte in i(20q-) group and20q-accompanied by other chromosomeabnormalities group were both higher than the isolate20q-group. The incidence ofmorphological changes in megakaryocyte which PMCC＞10%was most frequent ini(20q-) group,suggest that the bone marrow cells of i(20q-) group were easily to involvedin megakaryocyte. The incidence of morphological changes in erythroid and myeloidwhich PMCC＞10%was most frequent in20q-accompanied by other chromosomeabnormalities group,it may resulted from the complexity of the kayrotype. The mediansurvival time of isolate20q-group is longer than the i(20q-) group,and the20q-accompanied by other chromosome abnormalities group has the shortest median survivaltime.3.The DNA aCGH study on hematoligic malignancies with20q-abnormalityThe whole genomic aCGH analysis of21cases showed that,17cases had interstitial deletion of the long arm of chromosome20,of which8cases were two consecutive partialdeletions,9cases were continuity of large deletions.The overlap region of deleted regionsin the10cases of MDS was20q11.23, the overlap region of deleted regions in4cases ofAML was20q11.22-q13.2, the overlap region of deleted regions in2cases of ALL was20q11.21-q13.13,the deleted region in MPN was20q11.21-q13.2.We defined three CDRsand two CRRs, CDR1(14/17patients) spanned3.05Mb and was located in20q11.23(34,560,497-37,608,229). CDR2(16/17patients) spanned1.76Mb and waslocated in20q12(37,851,501-39,615,698). CDR3(14/17patients) spanned116kb and waslocated in20q13.13(48,120,412-48,236,791). CRR1(14/17patients)spanned1.1Mb, locatedin20q11.11(29,374,726-30,428，250).CRR2(14/17patients) spanned2.5Mb and waslocated in20q13.33(60,484,668-62,963,548). we used the UCSC Genome Browser andBioGPS based on their function and expression pattern (expression in bone marrow orblood cells) to pinpoint putative pathogenic genes of interest. CDR1,CDR2and CDR3spanned33、1and0genes known to be expressed in hematopoietic tissues, while CRR1and CRR2encompassed5and38genes, respectively.4.The clinical and laboratorial features of hematologic malignancies with t(20;21)The6cases with t(20;21) abnormalty accounting for2.3%of the20q-patients from2001.A panel FISH probes confirmed the existence of the20q-.The translocation breakingpoints of chromosome20which was translocated with chromosome21was20q11.Theelderly patient was domination(median age was55years old), and20q-is mainlyassociated with myeloid malignancies,especially with MDS(5cases of MDS,1case ofALL), the outcome is usually poor.Conclusions:Deletion of the long arm of chromosome20is a common abnormality associated withmyeloid malignancies,it is rarely seen in lymphoid malignancies,the elderly male weredomination. We can perform FISH test for those patients suspected of20q-by CC.Themedian survival of isolate20q-is relatively longer, but the outcome is inferior even ifone additional chromosome abnormality is present.The median survival in20q-smallclones is longer than in the large clones.so it can provide some prognostic information by following up the clone population changes.Although there’s no specific bone marrow morphological changes in i(20q-), theincidences of some morphological changes were significantly higher than in otherchromosome abnormalities groups,when we found those certain characteristicmorphological changes,we should take i(20q-) into account first.We defined3CDRs and2CRRs in20q-patients by aCGH, but it is still unknown thatwhether20q-cause the loss of several different tumor suppressor genes which result in thedistinct clinical and laboratorial features. So we need further study to reveal the pathogenicmechanism of the candidate genes.so as to provide some information to therapeutic targets.As i(20q-),der(20)del(20)(q11q12)t(20;21)(q11;q11) is a rare but recurringabnormality which derived from20q-, the elderly male patient was domination,and ismainly associated with myeloid malignancies,especially in MDS,rarely occurred inALL.The outcome of this abnormalty is poor. Translocation may play an important role insuch disorders by causing a new fusion gene.