Clinical Significance of the del(20q) Chromosome in Hematologic Disorders Merja Aatola, Elina Armstrong, Lasse Teerenhovi, and Georg H. Borgstr6m
Patients with hematologic neoplasias often have chromosomal aberrations in the cells of their bone marrow or unstimulated blood. One recurrent abnormality is a deletion of the long arm of chromosome 20, primarily described in polycythemia vera, but later seen in a range of hematologic disorders. We have studied 32 patients with del(2Oq) as the sole chromosomal aberration, investigating significance of this aberration for the clinical diagnoses, hematologic parameters, and prognoses within this patient group. According to our results, del(2Oq) is primarily associated with myeloid disorders, but it is not specific for any certain disease, nor does the proportion of cells with del(2Oq) correlate with prognosis. ABSTRACT:
INTRODUCTION Patients with hematologic neoplasias often have chromosomal aberrations in the cells of their bone marrow or uns t i m u l a t e d blood. These abnormalities often correlate with hematologic findings and prognosis. Kay and coworkers [1] detected a deletion of an F-group c h r o m o s o m e in patients with p o l y c y t h e m i a vera (PV) in 1966. In 1972, Reeves et al. [2] found that this deletion involved the long arm of c h r o m o s o m e 20. In more recent studies, m a n y investigators confirmed that del(20q) is indeed often seen in P. vera, but it has also been detected in other hematologic disorders such as m y e l o d y s p l a s t i c s y n d r o m e s (MDS), agnogenic m y e l o i d metaplasia (AMM), and acute n o n - l y m p h o c y t i c l e u k e m i a (ANLL) [3]. A p p r o x i mately half of the ANLL patients with this marker had erythroleukemia. However, in m a n y cases, other chromosomal aberrations besides the del(20q) were observed in the same mitosis. In the present study, clinical and hematologic data were collected from 32 patients w i t h del(20q) as the sole chromosomal aberration in their bone marrow or u n s t i m u l a t e d blood cells. These 32 patients were found among about 15,000 hematologic cytogenetic examinations carried out during 1978-1989. The p u r p o s e of this study was to evaluate the clinical significance of the del(20q) marker chromo-
From the Department of Medical Genetics (M. A., E.A., G. H. B.), University of Helsinki; and Department of Radiotherapy and Oncology (L. T.), Helsinki University Central Hospital, Helsinki, Finland. Address reprint requests to: G. H. BorgstrOm, M.D., Department of Medical Genetics, University of Helsinki, Haartmaninkatu 3, SF-00290 Helsinki, Finland. Received February 12, 1992; accepted May 1, 1992. ~g 1992 Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas. New York, NY 10010
some by analyzing the clinical diagnoses, hematologic parameters, and prognoses w i t h i n this patient group.
PATIENTS AND METHODS
The patients in this study were referred to the Department of Medical Genetics, University of Helsinki, F i n l a n d or to the Clinical Laboratory Medix, Espoo, F i n l a n d for routine chromosomal examinations because of an overt or suspected hematologic d i s o r d e r during the period of 1978-1989. The total n u m b e r of cytogenetic e x a m i n a t i o n s carried out in these centers during that time was about 15,000. We chose for study patients with del(20q) as the sole a b n o r m a l i t y in their bone m a r r o w (31 patients) or u n s t i m u l a t e d p e r i p h e r a l blood cells (one patient). The samples were referred from hospitals in various parts of Finland. The clinical data of the patients were collected from their medical records, and the patients were followed through September 1989 or until death. The diagnoses and hematologic data given at the time of each c h r o m o s o m a l analysis were recorded. Cytogenetic investigations were performed using the G-banding technique on bone m a r r o w and p e r i p h e r a l blood cells [4]. The n u m b e r of mitoses e x a m i n e d varied from 5 to 27 per patient. A clone was c o n s i d e r e d to be present w h e n two or more cells s h o w e d the del(20q) abnormality. In 15 patients, the c h r o m o s o m a l analysis was performed prior to any radiation or cytostatic treatment. Seventeen patients had been treated with either radioactive p h o s p h o r u s alone or r a d i o t h e r a p y a n d / o r cytostatics. In 11 patients, the cytogenetic analysis was performed more than once (Table 1). Two patients who had a normal k a r y o t y p e at the initial examination were found to have the del(20q) marker in 75 Cancer Genet Cytogenet 62:75 80 (1992) 0165-4608/92/$05.00
76
Table 1
P a t i e n t no.
C l i n i c a l a n d c y t o g e n e t i c f i n d i n g s i n 32 p a t i e n t s w i t h d e l ( 2 0 q )
Age/sex
1 2
59/F 58/I*"
3 4 5
62/M 70/F 76/F
6 7 8
70/M 67/F 69/F
9 10 11 12 13
57/M 71/F 71/F 70/M 38/M
14
75/F
15 16 17
48/F 58/M 80/M
18
55/F
19 2O 21 22 23 24
74/F 75/M 77/F 55/F 72/M 67/M
25
81/F
26 27 28 29
79/M 76/F 59/M 76/M
30 31
68/M 61/F
32
75/M
Del(20q) c e l l s % (total no. of mitoses analyzed]
Previous treatment
S u r v i v a l (mont hs )
Diagnoses
40(15) 75{g) 33{15} 80(15) 31(16) 0(5) 65(17) 13(15) 72{11) 100(7) 100(7) 18(17) 13(15) 39(18) 37(19) 0(17) 4(24) 5(22) 82(17) 72(18) 36(22) 20{25) 38{8) 8(12) 18(17] 19(27] 38(13] 60(15) 13(16) 70(20) 53(17] 55(11) 63(19) 93(14) 22(9) 13(15} 79(19) 65(20) 95(19) 5o{18) 10O(lO) 56(18) 47(19} 62{13} 69{16) 42{12) 67(6) 64(11) 45(11) 71{14) 56(18) 16(19)
No No Yes Yes No Yes Yes No No No Yes Yes Yes No No Yes Yes --~' No Yes '~ " ~' " Yes Yes No No No Yes --" Yes Yes No Yes Yes No " " --" --" No ---" No No Yes Yes " Yes Yes " No
46 +
MDS AA ANLL P P MM MDS PV PV AL. u n d e f i n e d AMM PV PV ANLL PPMM MDS ANLL ET ET ET PV PV PV PV Anemia MDS? Anemia PV MDS MDS MDS PV PV PV PV MDS PV PV MDS? MDS? MDS? MDS? MDS MDS MDS MDS? PV PV PPMM P P MM (PV)MDS *' PV PV AL, u n d e f i n e d
7 < 1 1 < 1 < 1 58 108 16 132 + 29 + 3
48 ~
148 + 2 91 +
14 68+ 81 + 15 15 + 72 + 12 +
74 + 14 15 + 16 ~ 108 + 41 6 113 2
" There was no treatment between the chromosomal analyses. J' The patient had been previously diagnosed with PV, but at the time of the first chromosomal analysis the case was diagnosed a MDS. Abbre, viotions: MDS, myelodysplastic syndrome; AA, aplastic anemia; ANLL, acute nonlymphocytic leukemia; PPMM, postpolycy
temic myeloid metaplasia; PV, polycythemia vera; AL, acute leukemia; ET. essential thrombocytopenia.
del(20q) in Hematological Disorders
77
del 20(q11) No.
24 Z
v
27
20 Figure I Schematic presentation of chromosome 20 and partial karyotypes of two patients, one with the common large del(20)(q11) (no. 24) and one with a shorter deletion, probably del(20)(qllq13.2) (no. 27). later studies. All patients had a normal karyotype in stimulated p e r i p h e r a l blood l y m p h o c y t e cultures. The statistical analyses i n c l u d e d the log-rank test (prognostic significance of del(20q)) [5] and correlation analysis (analysis of the relationship between blood values and the n u m b e r of del(20q) positive mitoses).
RESULTS Cytogenetic Findings In the initial 32 samples, the mean percentage of cells with the del(20q) clone was 47%. Two patients had a normal karyotype in the first study, but in follow-up investigations, a clone with del(20q) was detected. Fifteen patients initially had both normal mitoses and mitoses with del(20q). Twelve patients had no normal mitoses; they had clonal del(20q) and in a d d i t i o n m a n y n o n c l o n a l karyotypic abnormalities. Only one patient (No. 8) had the del(20q) marker in all mitoses studied. Two patients also had an a d d i t i o n a l clonal abnormality: 47,XY,del(20q),+C or 47,XY,del(20q), + 9. In 11 patients, the karyotype was e x a m i n e d twice or several times (Table 1). Nine of these patients had the del(20q) clone in the first study. The percentage of mitoses w i t h del(20q) t e n d e d to decrease in subsequent investigations. In the first investigation, this clone was detected in a mean of 71% (SD 17) of the mitoses, whereas in the second investigation the c o r r e s p o n d i n g value was only 61% (SD 18). This difference was, however, statistically nonsignificant. Two patients (Nos. 5 and 13) had a normal karyotype in the first investigation, but exhibited a del(20q) clone in subsequent studies.
Breakpoints The breakpoints were localized in band 2 0 q l l in all 32 patients d e c i d e d u p o n by c o n v e n t i o n a l cytogenetics. The amount of c h r o m o s o m a l material left on the long arm was m i n u t e in 31 patients. In one patient (No. 27), there was clearly a larger portion left in w h i c h no dark band was seen (Fig. 1); the deletion was thus probably del(20)(qllq13.2).
Clinical Findings The m e d i a n age of the patients was 70 years, ranging from 38 to 82 years. There were 17 w o m e n and 15 men. Seventeen patients had received chemo- a n d / o r r a d i o t h e r a p y for their hematologic illness before the first karyotype analysis. The clinical diagnoses after the first karyotype analyses are presented in Table 2. Eighteen patients had a myeloproliferative syndrome, most often diagnosed as PV. The rest of the patients had MDS, ANLL, u n d e f i n e d leukemia, u n d e f i n e d anemia, or aplastic anemia. The initial blood values, i n c l u d i n g hematocrit (Hct), mean corpuscular v o l u m e (MCV), white blood cell count, and platelet count, are given in block diagrams in Fig. 2. It is noteworthy that although 12 patients had a diagnosis of P. vera, only two patients had an a b n o r m a l l y high Hcr value. The MCV of red cells was, with certain exceptions, in the normal range. Low MCV values (fl < 80) were seen in five patients and high values (fl > 96) in six patients. The mean leukocyte count was higher than normal, but the SD was large. The mean platelet count was w i t h i n the
Table 2 Diagnoses of 57 patients in 15 p u b l i s h e d series and of the 32 patients in the present study Disease
Literature
Present study
Polycythemia vera Myelodysplastic syndrome Agnogenic myeloid metaplasia ANLL CML Essential thrombocytosis Undefined leukemia Undefined anemia Aplastic anemia ALL
35%" 26% 16% 14% 6%
37% 22% 13% 6%
2%
6% 6% 6% 3%
2%
" One patient had undefined myeloproliferative disease. Abbreviations: ANLL, acute nonlymphocytic leukemia (AML); CML chronic myeloid leukemia; ALL,acute lymphatic leukemia.
78
M. AatoJa et al. %
,55.
,51
0
o
110.
0
9590-
'35 t
,31
0
500.
25-
II
80 ,25J
.
20-
O
"]"
4001
15. " ~
300.
10
200.
75. 0 0
600.
30-
0
100-
,41
109/L 700
0
105-
,451
109/L 35.
FL 115.
--1
100]
0
70 o
,15
,
H~
65
|
MCV
0
8 ,
WBC
O/
Platelets
Figure 2 Block diagrams of hematocrit, mean cellular volume, and white blood cell and platelet counts at the time of the first karyotype study of 32 patients. Highest WBC (74 x 10~/L) and platelet (999 and 980 x 109/L) values are not shown in respective box plot pictures.
normal range (140-350 × 10~/L), but abnormally high or low values were m e a s u r e d in 8 and 12 patients, respectively. A regression analysis was done to correlate the initial blood values with the proportion of mitoses with del(20q), but no significant association was found in any of the analyses. Clinical Evolution
Only three patients in this study s h o w e d clinical evolution. One patient had MDS at the time of first c h r o m o s o m a l analysis, but later d e v e l o p e d an ANLL. A n o t h e r patient progressed from aplastic a n e m i a to ANLL w i t h i n 5 months and a third patient from PV to MDS within 8 years (Table 1). Survival and Causes of Death
The period of survival ranged from 2 days to over 148 months (Table 1), as calculated from the time of chromosomal analysis. By the end of the study period, 19 patients had died. The m e a n survival period was 52 months. A high or low count of mitoses with del(20q) had no prognostic significance for survival. Survival actually tended to be longer in patients having a high proportion of mitoses with del(20q) than in those with a low proportion. This difference was, however, statistically nonsignificant. The diagnoses at the time of death were ANLL or undefined l e u k e m i a (five patients), AMM (five patients), PV (four patients), MDS (four patients), and breast cancer (one patient). The i m m e d i a t e causes of death were infection in seven, bleeding in three, and t h r o m b o e m b o l i c complications in two patients.
DISCUSSION
The clinical significance of del(20q) was evaluated in patients with del(20q) as the sole abnormality. A literature review y i e l d e d 57 such cases in 15 studies [6-21]. The clinical diagnoses of these patients are p r e s e n t e d in Table 2. The data collected from the literature show a disease profile very similar to that found in the present study; most of the patients had PV, AMM, MDS, or ANLL. These disorders are related to each other, as untreated P. vera can develop into A M M and ANLL. The so-called spent phase of PV often mimics genuine MDS. MDS can also precede the d e v e l o p m e n t of ANLL in PV patients. Although del(20q) is not a specific marker of any certain disease, it seems to be a marker of related disease entities, as mentioned above. Three CML patients with del(20q) as the sole cytogenetic a b e r r a t i o n - - t h e s e patients did not have the P h i l a d e l p h i a c h r o m o s o m e - - h a v e been described in the literature [8, 20]. As there are no precise m o r p h o l o g i c criteria for CML, the diagnosis of this disease should be based, together with certain hematologic findings, on the presence of the Philad e l p h i a c h r o m o s o m e or on the detection of a BCR gene rearrangement. The latter was not s t u d i e d in these three patients. Because there is only one p u b l i s h e d case of ALL with del(20q) as the sole aberration [7], del(20q) appears to be associated almost solely with m y e l o i d disorders. Two patients (Nos. 5 and 13) in the present s t u d y had a normal karyotype at the first c h r o m o s o m a l analysis and d e v e l o p e d a clone with del(20q) later in the course of the disease (Table 3). The aberration m a y therefore not be primarily related to the cause of hematologic disorders. The
del(20q) in Hematological Disorders
Table 3 Patient no.
79
Karyotype evolution Age/sex
Date (month/year)
Karyotype
5
76/F
8
69/F
13
38/M
14
75/F
3/8O 2/85 9/8O 2/81 9/78 2/83 10/85 5/78
46,XX 46,XX/46,XX,del(20)(q11.2) 46,XX,del(20)(q11) 46,XX,del(20)(p), del(20)(q11),- 12,-C, + 2mar 46,XY 46,XY 46,XY/46,XY,del(20)(q11.2) 46,XX/46,XX,deI(20)(q11.2) 46,XX/46,XX,del(20)(q11.2) 46,XX/46,XX,del(20)(q11.2) 46,XX/46,XX,deI(20)(q11.2) 46,XX/46,XX,deI(20)(q11.2) 46,XX/46,XX,del(20)(q11.2)/47,XX, + 8,del(20)(q11.2)) 46,XY/46,XY,deI(20)(q11.2) 46,XY/46,XY,del(20)(q11.2) 46,XY/46,XY,del(20)(ql 1.2), - 20, + mar ( + variations)
5/79
17
80/M
12/81 1/82 4/82 4/86 12/81 3/82 11/82
Patient 17 was untreated. Patients 14 and 17 also showed clinical evolution.
observation that 16 of the 32 patients in the present series had the del(20q) marker before any irradiation or cytostatic treatment is in agreement with the findings in other series and indicates that the marker is not secondary to these treatments. The etiology of the del(20q) marker remains obscure. Karyotype evolution took place in five patients in the present series (Table 3). A c h r o m o s o m a l analysis was performed only once in 21 patients and twice or several times in 11 patients. In one patient (No. 14), karyotype evolution c o i n c i d e d with clinical evolution from PV to suspected MDS. A m o n g 57 patients p r e s e n t e d in the literature, only one patient exhibited karyotype evolution, a clone with del(1)(q427) to a clone with del(20)(q11) [20]. Clinical evolution was found in five patients, all initially having PV; the n e w diagnoses were chronic megakaryocytic-granulocytic myelosis, osteomyelofibrosis/myelosclerosis, myeloid metaplasia, and acute l e u k e m i a after m y e l o i d metaplasia [13, 19]. These findings support previous studies w h i c h i n d i c a t e d that the presence of new cytogenetically abnormal clones d i d not allow p r e d i c t i o n of the evolution of the disease [6]. The period of survival varied from 12 days to over 148 months among the five patients with clonal evolution in the present study. The patient with the longest survival was still alive 148 months after the initial analysis despite the clonal evolution. Previous studies report survival periods of 1 6 - 7 9 months for del(20q) patients [12]. A high proportion of mitoses with a del(20q) a b n o r m a l i t y is not, in itself, a bad prognostic sign. In the present series, patients with the most cells containing the del(20q) marker lived longer than patients in w h o m only a small p r o p o r t i o n of cells contained the del(20q) marker. The only patient in w h o m all mitoses exhibited the del(20q) marker actually lived 108 months (mean survival in the present series was 52 months). These results are s o m e w h a t c o n t r a d i c t o r y to the suggestion made
by Jarosova et al. [13] that the absence of cells w i t h a normal karyotype w o u l d i m p l y a poor prognosis. In the present study, the p r o p o r t i o n of mitoses with the del(20q) marker tended not to increase, but to decrease in subsequent investigations. The d i s a p p e a r a n c e of del(20q) has been reported twice in the literature [8, 22]. The del(20q) breakpoint is reported to be in band 20q11. Whether the del(20q) is interstitial or terminal cannot be d e t e r m i n e d using cytogenetic techniques. Le Beau et al. [15], using DNA methods, observed that del(20q) was interstitial rather than terminal. They s h o w e d that the SRC locus, encoding the c-src oncogene n o r m a l l y located in the most distal band of 20q, was conserved in del(20q). However, this was not the case in two patients w i t h del(20q) studied by Morris et al. [16]. By in situ h y b r i d i z a t i o n they found loss of one allele of c-src in both patients s t u d i e d suffering from Ph positive ALL and PV d e v e l o p i n g into AML and M5, respectively. Thus the role of the c°src oncogene in patient with del(20q) remains obscure. The a m o u n t of material remaining in bands 2 0 q l l and 20q13 was minimal in 31 of the patients in the present series, with no obvious variation. In one patient (No. 27], the d e l e t i o n was smaller (Fig. 1). It was not possible to d e t e r m i n e w h i c h of the two bands m e n t i o n e d was present more extensively in this patient. Based on this study and on reports in the literature, the del[20q) marker appears to be p r i m a r i l y associated with m y e l o i d disorders. It is not a marker of any specific disease but rather of certain disease entities: PV, AMM, MDS, and ANLL. del(20q) occurs in both treated and untreated patients and thus it is not i n d u c e d by therapy. The proportion of ceils with the del(20q) marker does not correlate with prognosis. Clinical evolution is rarely seen in conjunction with karyotype evolution. The deletion is c o n s i d e r e d to be interstitial, based on m o l e c u l a r studies, and in most cases it is large, with very little r e m a i n i n g of b a n d s 2 0 q l l
80
and 20q13. The role of the src o n c o g e n e , w h i c h is situated in the b r e a k p o i n t area, is still u n c l e a r in the p a t h o g e n e s i s of the a b o v e disorders.
REFERENCES 1. Kay HEM, Lawler SD, Millard RE (1966): The chromosomes in polycythaemia vera. Br l Haematol 12:507-582. 2. Reeves BR, Lobb DS, Lawler SD (1972): Identity of the abnormal F-group chromosome associated with polycythaeinia vera. Humangenetik 14:159-16l. 3. Helm S, Mitelman F (1986): Secondary chromosome aberrations in acute leukemias. Cancer Genet Cytogenet 22:331-338. 4. Seabright M (1971): A rapid banding technique for human chromosomes. Lancet ii:971-972. 5. Peto R, Pike MC, Armitage P, Breslow NE, Cox DR, Howard SV, Mantel N, McPherson K, Peto [, Smith PG (1977): Design and analysis of randomized clinical trials requiring prolonged observation of each patient. II. Analysis and examples. Br J Cancer 35:1-39. 6. Berger R, Bernheim A, Le Coniat M, Vecchione D, Flandrin G, Dresch C, Najean Y (1984): Chromosome studies in polycythemia vera patients. Cancer Genet Cytogenet 12:217-223. 7. Colon-Otero G, Li C-H, Dewald GW, White WL (1981): Erythrophagocytic acute lymphocytic leukemia with B-cell markers and with a 20q-chromosome abnormality. Mayo Clin Proc 59:678-682. 8. Davis MP, Dewald GW, Pierre RV, Hoagland HC (1984): Hematologic manifestations associated with deletions of the long arm of chromosome 20. Cancer Genet Cytogenet 12:63-71. 9. Demory JL, Dupriez B, Fenaux P, Lai JL, Beauscart R, Jouet JP, Deminatti M, Bauters F (1988): Cytogenetic studies and their prognostic significance in agnogenic myeloid metaplasia: A report of 47 cases. Blood 72:855-859. 10. Findley L, Kurnick JE, Peakman DC, Robinson A (1979): Chromosome deletion [46, XX, del(20)(q11)] in agnogenic myeloid metaplasia. Hum Genet 47:207-211.
M. A a t o l a et al.
11. Fleichman EW, Prigogina EL, Volkova MA, Kulagina OE (1979): Chromosomal marker 2 0 q - in cases of osteomyeh)sclerosis and CML. Hum Genet 50:101-I04. 12. Jacobs RH, Cornbleet MA, Vardiman JW, Larson RA, LeBeau MM, Rowley JD (1986): Prognostic implications of morphology and karyotype in primary myelodysplastic syndromes. Blood 67:1765-1772.
13, )arosova M, lndrak K, Dusek ], Kapustova M (1988): Cytogenetic studies in polycythemia vera. Neoplasma 35:221-227. 14. Knapp RH, Dewald GW, Pierre RV (1985): Cytogenetic studies in 174 consecutive patients with preleukemic or myelodysplastic syndromes. Mayo Clin Proc 60:507-516. 15. Le Beau MM, Westbrook CA, Diaz MO, Rowley JD ( 1985): c-src is consistently conserved in the chromosomal deletion (20ql observed in myeloid disorders. Proc Natl Acad Sci USA 82:6692 6696. 16. Morris CM, Honeybone LM, Hollings PE, Fitzgeraht PH (1989): Localization of the SRC oncogene to chromosome band 20qll .2 and loss of this gene with deletion (20q) in twa leukemic patients. Blood 74:1768-1773. 17. Miller B, Testa JR, Liugren V, Rowley ID (1985): The pattern and clinical significance of karyotypic abnormalities in patients with idiopathic and postpolycythemic myelofibrosis. Cancer 55:582-591. 18. Rege-Gambrin G, Mecucci C, Tricot G, Michaux J-L, Louwagie A, Van Hove W, Francart H, Van den Berghe H (1987): A chromosomal profile of polycythemia vera. Cancer Genet Cytogenet 25:233-245. 19. Swolin B, Weinfeld A, Westin l (1988): A prospective longterm cytogenetic study in polycythemia vera in relation to treatment and clinical course. Blood 72:386-395. 20. Testa JR, Kinnealey A, Rowley JD, Golde DW, Potter D (1978]: Deletion of the long arm of chromosome 20 [del(20)[q11)] in myeloid disorders. Blood 52:868-877. 21. Zech L, Gahrton C, Killander D, Franzen S, Haglund U (1976): Specific chromosomal aberrations in polycythemia vera. Blood 48:687-696. 22. Lawler SD (1980): Cytogenetic studies in Ph chromosomenegative myeloproliferative disorders, particularly PV. Clin Haematol 9:159-174.
Patients with hematologic neoplasias often have chromosomal aberrations in the cells of their bone marrow or unstimulated blood. One recurrent abnormality is a deletion of the long arm of chromosome 20, primarily described in polycythemia vera, but later seen in a range of hematologic disorders. We have studied 32 patients with del(2Oq) as the sole chromosomal aberration, investigating significance of this aberration for the clinical diagnoses, hematologic parameters, and prognoses within this patient group. According to our results, del(2Oq) is primarily associated with myeloid disorders, but it is not specific for any certain disease, nor does the proportion of cells with del(2Oq) correlate with prognosis. ABSTRACT:
INTRODUCTION Patients with hematologic neoplasias often have chromosomal aberrations in the cells of their bone marrow or uns t i m u l a t e d blood. These abnormalities often correlate with hematologic findings and prognosis. Kay and coworkers [1] detected a deletion of an F-group c h r o m o s o m e in patients with p o l y c y t h e m i a vera (PV) in 1966. In 1972, Reeves et al. [2] found that this deletion involved the long arm of c h r o m o s o m e 20. In more recent studies, m a n y investigators confirmed that del(20q) is indeed often seen in P. vera, but it has also been detected in other hematologic disorders such as m y e l o d y s p l a s t i c s y n d r o m e s (MDS), agnogenic m y e l o i d metaplasia (AMM), and acute n o n - l y m p h o c y t i c l e u k e m i a (ANLL) [3]. A p p r o x i mately half of the ANLL patients with this marker had erythroleukemia. However, in m a n y cases, other chromosomal aberrations besides the del(20q) were observed in the same mitosis. In the present study, clinical and hematologic data were collected from 32 patients w i t h del(20q) as the sole chromosomal aberration in their bone marrow or u n s t i m u l a t e d blood cells. These 32 patients were found among about 15,000 hematologic cytogenetic examinations carried out during 1978-1989. The p u r p o s e of this study was to evaluate the clinical significance of the del(20q) marker chromo-
From the Department of Medical Genetics (M. A., E.A., G. H. B.), University of Helsinki; and Department of Radiotherapy and Oncology (L. T.), Helsinki University Central Hospital, Helsinki, Finland. Address reprint requests to: G. H. BorgstrOm, M.D., Department of Medical Genetics, University of Helsinki, Haartmaninkatu 3, SF-00290 Helsinki, Finland. Received February 12, 1992; accepted May 1, 1992. ~g 1992 Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas. New York, NY 10010
some by analyzing the clinical diagnoses, hematologic parameters, and prognoses w i t h i n this patient group.
PATIENTS AND METHODS
The patients in this study were referred to the Department of Medical Genetics, University of Helsinki, F i n l a n d or to the Clinical Laboratory Medix, Espoo, F i n l a n d for routine chromosomal examinations because of an overt or suspected hematologic d i s o r d e r during the period of 1978-1989. The total n u m b e r of cytogenetic e x a m i n a t i o n s carried out in these centers during that time was about 15,000. We chose for study patients with del(20q) as the sole a b n o r m a l i t y in their bone m a r r o w (31 patients) or u n s t i m u l a t e d p e r i p h e r a l blood cells (one patient). The samples were referred from hospitals in various parts of Finland. The clinical data of the patients were collected from their medical records, and the patients were followed through September 1989 or until death. The diagnoses and hematologic data given at the time of each c h r o m o s o m a l analysis were recorded. Cytogenetic investigations were performed using the G-banding technique on bone m a r r o w and p e r i p h e r a l blood cells [4]. The n u m b e r of mitoses e x a m i n e d varied from 5 to 27 per patient. A clone was c o n s i d e r e d to be present w h e n two or more cells s h o w e d the del(20q) abnormality. In 15 patients, the c h r o m o s o m a l analysis was performed prior to any radiation or cytostatic treatment. Seventeen patients had been treated with either radioactive p h o s p h o r u s alone or r a d i o t h e r a p y a n d / o r cytostatics. In 11 patients, the cytogenetic analysis was performed more than once (Table 1). Two patients who had a normal k a r y o t y p e at the initial examination were found to have the del(20q) marker in 75 Cancer Genet Cytogenet 62:75 80 (1992) 0165-4608/92/$05.00
76
Table 1
P a t i e n t no.
C l i n i c a l a n d c y t o g e n e t i c f i n d i n g s i n 32 p a t i e n t s w i t h d e l ( 2 0 q )
Age/sex
1 2
59/F 58/I*"
3 4 5
62/M 70/F 76/F
6 7 8
70/M 67/F 69/F
9 10 11 12 13
57/M 71/F 71/F 70/M 38/M
14
75/F
15 16 17
48/F 58/M 80/M
18
55/F
19 2O 21 22 23 24
74/F 75/M 77/F 55/F 72/M 67/M
25
81/F
26 27 28 29
79/M 76/F 59/M 76/M
30 31
68/M 61/F
32
75/M
Del(20q) c e l l s % (total no. of mitoses analyzed]
Previous treatment
S u r v i v a l (mont hs )
Diagnoses
40(15) 75{g) 33{15} 80(15) 31(16) 0(5) 65(17) 13(15) 72{11) 100(7) 100(7) 18(17) 13(15) 39(18) 37(19) 0(17) 4(24) 5(22) 82(17) 72(18) 36(22) 20{25) 38{8) 8(12) 18(17] 19(27] 38(13] 60(15) 13(16) 70(20) 53(17] 55(11) 63(19) 93(14) 22(9) 13(15} 79(19) 65(20) 95(19) 5o{18) 10O(lO) 56(18) 47(19} 62{13} 69{16) 42{12) 67(6) 64(11) 45(11) 71{14) 56(18) 16(19)
No No Yes Yes No Yes Yes No No No Yes Yes Yes No No Yes Yes --~' No Yes '~ " ~' " Yes Yes No No No Yes --" Yes Yes No Yes Yes No " " --" --" No ---" No No Yes Yes " Yes Yes " No
46 +
MDS AA ANLL P P MM MDS PV PV AL. u n d e f i n e d AMM PV PV ANLL PPMM MDS ANLL ET ET ET PV PV PV PV Anemia MDS? Anemia PV MDS MDS MDS PV PV PV PV MDS PV PV MDS? MDS? MDS? MDS? MDS MDS MDS MDS? PV PV PPMM P P MM (PV)MDS *' PV PV AL, u n d e f i n e d
7 < 1 1 < 1 < 1 58 108 16 132 + 29 + 3
48 ~
148 + 2 91 +
14 68+ 81 + 15 15 + 72 + 12 +
74 + 14 15 + 16 ~ 108 + 41 6 113 2
" There was no treatment between the chromosomal analyses. J' The patient had been previously diagnosed with PV, but at the time of the first chromosomal analysis the case was diagnosed a MDS. Abbre, viotions: MDS, myelodysplastic syndrome; AA, aplastic anemia; ANLL, acute nonlymphocytic leukemia; PPMM, postpolycy
temic myeloid metaplasia; PV, polycythemia vera; AL, acute leukemia; ET. essential thrombocytopenia.
del(20q) in Hematological Disorders
77
del 20(q11) No.
24 Z
v
27
20 Figure I Schematic presentation of chromosome 20 and partial karyotypes of two patients, one with the common large del(20)(q11) (no. 24) and one with a shorter deletion, probably del(20)(qllq13.2) (no. 27). later studies. All patients had a normal karyotype in stimulated p e r i p h e r a l blood l y m p h o c y t e cultures. The statistical analyses i n c l u d e d the log-rank test (prognostic significance of del(20q)) [5] and correlation analysis (analysis of the relationship between blood values and the n u m b e r of del(20q) positive mitoses).
RESULTS Cytogenetic Findings In the initial 32 samples, the mean percentage of cells with the del(20q) clone was 47%. Two patients had a normal karyotype in the first study, but in follow-up investigations, a clone with del(20q) was detected. Fifteen patients initially had both normal mitoses and mitoses with del(20q). Twelve patients had no normal mitoses; they had clonal del(20q) and in a d d i t i o n m a n y n o n c l o n a l karyotypic abnormalities. Only one patient (No. 8) had the del(20q) marker in all mitoses studied. Two patients also had an a d d i t i o n a l clonal abnormality: 47,XY,del(20q),+C or 47,XY,del(20q), + 9. In 11 patients, the karyotype was e x a m i n e d twice or several times (Table 1). Nine of these patients had the del(20q) clone in the first study. The percentage of mitoses w i t h del(20q) t e n d e d to decrease in subsequent investigations. In the first investigation, this clone was detected in a mean of 71% (SD 17) of the mitoses, whereas in the second investigation the c o r r e s p o n d i n g value was only 61% (SD 18). This difference was, however, statistically nonsignificant. Two patients (Nos. 5 and 13) had a normal karyotype in the first investigation, but exhibited a del(20q) clone in subsequent studies.
Breakpoints The breakpoints were localized in band 2 0 q l l in all 32 patients d e c i d e d u p o n by c o n v e n t i o n a l cytogenetics. The amount of c h r o m o s o m a l material left on the long arm was m i n u t e in 31 patients. In one patient (No. 27), there was clearly a larger portion left in w h i c h no dark band was seen (Fig. 1); the deletion was thus probably del(20)(qllq13.2).
Clinical Findings The m e d i a n age of the patients was 70 years, ranging from 38 to 82 years. There were 17 w o m e n and 15 men. Seventeen patients had received chemo- a n d / o r r a d i o t h e r a p y for their hematologic illness before the first karyotype analysis. The clinical diagnoses after the first karyotype analyses are presented in Table 2. Eighteen patients had a myeloproliferative syndrome, most often diagnosed as PV. The rest of the patients had MDS, ANLL, u n d e f i n e d leukemia, u n d e f i n e d anemia, or aplastic anemia. The initial blood values, i n c l u d i n g hematocrit (Hct), mean corpuscular v o l u m e (MCV), white blood cell count, and platelet count, are given in block diagrams in Fig. 2. It is noteworthy that although 12 patients had a diagnosis of P. vera, only two patients had an a b n o r m a l l y high Hcr value. The MCV of red cells was, with certain exceptions, in the normal range. Low MCV values (fl < 80) were seen in five patients and high values (fl > 96) in six patients. The mean leukocyte count was higher than normal, but the SD was large. The mean platelet count was w i t h i n the
Table 2 Diagnoses of 57 patients in 15 p u b l i s h e d series and of the 32 patients in the present study Disease
Literature
Present study
Polycythemia vera Myelodysplastic syndrome Agnogenic myeloid metaplasia ANLL CML Essential thrombocytosis Undefined leukemia Undefined anemia Aplastic anemia ALL
35%" 26% 16% 14% 6%
37% 22% 13% 6%
2%
6% 6% 6% 3%
2%
" One patient had undefined myeloproliferative disease. Abbreviations: ANLL, acute nonlymphocytic leukemia (AML); CML chronic myeloid leukemia; ALL,acute lymphatic leukemia.
78
M. AatoJa et al. %
,55.
,51
0
o
110.
0
9590-
'35 t
,31
0
500.
25-
II
80 ,25J
.
20-
O
"]"
4001
15. " ~
300.
10
200.
75. 0 0
600.
30-
0
100-
,41
109/L 700
0
105-
,451
109/L 35.
FL 115.
--1
100]
0
70 o
,15
,
H~
65
|
MCV
0
8 ,
WBC
O/
Platelets
Figure 2 Block diagrams of hematocrit, mean cellular volume, and white blood cell and platelet counts at the time of the first karyotype study of 32 patients. Highest WBC (74 x 10~/L) and platelet (999 and 980 x 109/L) values are not shown in respective box plot pictures.
normal range (140-350 × 10~/L), but abnormally high or low values were m e a s u r e d in 8 and 12 patients, respectively. A regression analysis was done to correlate the initial blood values with the proportion of mitoses with del(20q), but no significant association was found in any of the analyses. Clinical Evolution
Only three patients in this study s h o w e d clinical evolution. One patient had MDS at the time of first c h r o m o s o m a l analysis, but later d e v e l o p e d an ANLL. A n o t h e r patient progressed from aplastic a n e m i a to ANLL w i t h i n 5 months and a third patient from PV to MDS within 8 years (Table 1). Survival and Causes of Death
The period of survival ranged from 2 days to over 148 months (Table 1), as calculated from the time of chromosomal analysis. By the end of the study period, 19 patients had died. The m e a n survival period was 52 months. A high or low count of mitoses with del(20q) had no prognostic significance for survival. Survival actually tended to be longer in patients having a high proportion of mitoses with del(20q) than in those with a low proportion. This difference was, however, statistically nonsignificant. The diagnoses at the time of death were ANLL or undefined l e u k e m i a (five patients), AMM (five patients), PV (four patients), MDS (four patients), and breast cancer (one patient). The i m m e d i a t e causes of death were infection in seven, bleeding in three, and t h r o m b o e m b o l i c complications in two patients.
DISCUSSION
The clinical significance of del(20q) was evaluated in patients with del(20q) as the sole abnormality. A literature review y i e l d e d 57 such cases in 15 studies [6-21]. The clinical diagnoses of these patients are p r e s e n t e d in Table 2. The data collected from the literature show a disease profile very similar to that found in the present study; most of the patients had PV, AMM, MDS, or ANLL. These disorders are related to each other, as untreated P. vera can develop into A M M and ANLL. The so-called spent phase of PV often mimics genuine MDS. MDS can also precede the d e v e l o p m e n t of ANLL in PV patients. Although del(20q) is not a specific marker of any certain disease, it seems to be a marker of related disease entities, as mentioned above. Three CML patients with del(20q) as the sole cytogenetic a b e r r a t i o n - - t h e s e patients did not have the P h i l a d e l p h i a c h r o m o s o m e - - h a v e been described in the literature [8, 20]. As there are no precise m o r p h o l o g i c criteria for CML, the diagnosis of this disease should be based, together with certain hematologic findings, on the presence of the Philad e l p h i a c h r o m o s o m e or on the detection of a BCR gene rearrangement. The latter was not s t u d i e d in these three patients. Because there is only one p u b l i s h e d case of ALL with del(20q) as the sole aberration [7], del(20q) appears to be associated almost solely with m y e l o i d disorders. Two patients (Nos. 5 and 13) in the present s t u d y had a normal karyotype at the first c h r o m o s o m a l analysis and d e v e l o p e d a clone with del(20q) later in the course of the disease (Table 3). The aberration m a y therefore not be primarily related to the cause of hematologic disorders. The
del(20q) in Hematological Disorders
Table 3 Patient no.
79
Karyotype evolution Age/sex
Date (month/year)
Karyotype
5
76/F
8
69/F
13
38/M
14
75/F
3/8O 2/85 9/8O 2/81 9/78 2/83 10/85 5/78
46,XX 46,XX/46,XX,del(20)(q11.2) 46,XX,del(20)(q11) 46,XX,del(20)(p), del(20)(q11),- 12,-C, + 2mar 46,XY 46,XY 46,XY/46,XY,del(20)(q11.2) 46,XX/46,XX,deI(20)(q11.2) 46,XX/46,XX,del(20)(q11.2) 46,XX/46,XX,del(20)(q11.2) 46,XX/46,XX,deI(20)(q11.2) 46,XX/46,XX,deI(20)(q11.2) 46,XX/46,XX,del(20)(q11.2)/47,XX, + 8,del(20)(q11.2)) 46,XY/46,XY,deI(20)(q11.2) 46,XY/46,XY,del(20)(q11.2) 46,XY/46,XY,del(20)(ql 1.2), - 20, + mar ( + variations)
5/79
17
80/M
12/81 1/82 4/82 4/86 12/81 3/82 11/82
Patient 17 was untreated. Patients 14 and 17 also showed clinical evolution.
observation that 16 of the 32 patients in the present series had the del(20q) marker before any irradiation or cytostatic treatment is in agreement with the findings in other series and indicates that the marker is not secondary to these treatments. The etiology of the del(20q) marker remains obscure. Karyotype evolution took place in five patients in the present series (Table 3). A c h r o m o s o m a l analysis was performed only once in 21 patients and twice or several times in 11 patients. In one patient (No. 14), karyotype evolution c o i n c i d e d with clinical evolution from PV to suspected MDS. A m o n g 57 patients p r e s e n t e d in the literature, only one patient exhibited karyotype evolution, a clone with del(1)(q427) to a clone with del(20)(q11) [20]. Clinical evolution was found in five patients, all initially having PV; the n e w diagnoses were chronic megakaryocytic-granulocytic myelosis, osteomyelofibrosis/myelosclerosis, myeloid metaplasia, and acute l e u k e m i a after m y e l o i d metaplasia [13, 19]. These findings support previous studies w h i c h i n d i c a t e d that the presence of new cytogenetically abnormal clones d i d not allow p r e d i c t i o n of the evolution of the disease [6]. The period of survival varied from 12 days to over 148 months among the five patients with clonal evolution in the present study. The patient with the longest survival was still alive 148 months after the initial analysis despite the clonal evolution. Previous studies report survival periods of 1 6 - 7 9 months for del(20q) patients [12]. A high proportion of mitoses with a del(20q) a b n o r m a l i t y is not, in itself, a bad prognostic sign. In the present series, patients with the most cells containing the del(20q) marker lived longer than patients in w h o m only a small p r o p o r t i o n of cells contained the del(20q) marker. The only patient in w h o m all mitoses exhibited the del(20q) marker actually lived 108 months (mean survival in the present series was 52 months). These results are s o m e w h a t c o n t r a d i c t o r y to the suggestion made
by Jarosova et al. [13] that the absence of cells w i t h a normal karyotype w o u l d i m p l y a poor prognosis. In the present study, the p r o p o r t i o n of mitoses with the del(20q) marker tended not to increase, but to decrease in subsequent investigations. The d i s a p p e a r a n c e of del(20q) has been reported twice in the literature [8, 22]. The del(20q) breakpoint is reported to be in band 20q11. Whether the del(20q) is interstitial or terminal cannot be d e t e r m i n e d using cytogenetic techniques. Le Beau et al. [15], using DNA methods, observed that del(20q) was interstitial rather than terminal. They s h o w e d that the SRC locus, encoding the c-src oncogene n o r m a l l y located in the most distal band of 20q, was conserved in del(20q). However, this was not the case in two patients w i t h del(20q) studied by Morris et al. [16]. By in situ h y b r i d i z a t i o n they found loss of one allele of c-src in both patients s t u d i e d suffering from Ph positive ALL and PV d e v e l o p i n g into AML and M5, respectively. Thus the role of the c°src oncogene in patient with del(20q) remains obscure. The a m o u n t of material remaining in bands 2 0 q l l and 20q13 was minimal in 31 of the patients in the present series, with no obvious variation. In one patient (No. 27], the d e l e t i o n was smaller (Fig. 1). It was not possible to d e t e r m i n e w h i c h of the two bands m e n t i o n e d was present more extensively in this patient. Based on this study and on reports in the literature, the del[20q) marker appears to be p r i m a r i l y associated with m y e l o i d disorders. It is not a marker of any specific disease but rather of certain disease entities: PV, AMM, MDS, and ANLL. del(20q) occurs in both treated and untreated patients and thus it is not i n d u c e d by therapy. The proportion of ceils with the del(20q) marker does not correlate with prognosis. Clinical evolution is rarely seen in conjunction with karyotype evolution. The deletion is c o n s i d e r e d to be interstitial, based on m o l e c u l a r studies, and in most cases it is large, with very little r e m a i n i n g of b a n d s 2 0 q l l
80
and 20q13. The role of the src o n c o g e n e , w h i c h is situated in the b r e a k p o i n t area, is still u n c l e a r in the p a t h o g e n e s i s of the a b o v e disorders.
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11. Fleichman EW, Prigogina EL, Volkova MA, Kulagina OE (1979): Chromosomal marker 2 0 q - in cases of osteomyeh)sclerosis and CML. Hum Genet 50:101-I04. 12. Jacobs RH, Cornbleet MA, Vardiman JW, Larson RA, LeBeau MM, Rowley JD (1986): Prognostic implications of morphology and karyotype in primary myelodysplastic syndromes. Blood 67:1765-1772.
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