Haematologica 2003 - Supplements

2.3 Molecular cytogenetic and prognostic impact
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CYTOGENETICS AND MULTIPLE MYELOMA: A
SPANISH MULTICENTER STUDY OF 497 PATIENTS
B. Gil Fournier, ML. Martín Ramos, NC. Gutiérrez, E.
Barreiro, FJ. Fernández Martínez, JJ. Lahuerta, JM.
Hernández, C. Grande, R. Martínez, A. Alegre, J. García-
Laraña, J. Bladé, A. Sureda, J. de la Rubia and JF. San
Miguel
On behalf of GEM group.
Introduction: The information about cytogenetics in Multiple
Myeloma (MM) is opened to identify and define the role of
chromosomal abnormalities on prognosis of MM. We have
initiated a National cytogenetics studio with newly diagnosed
MM Spanish patients, in order to permit a more accurate
description of cytogenetics anomalies in MM.
Patients and Methods: 497 untreated MM patients were studied,
recruited from 68 centres in Spain. Cytogenetics analysis was
performed on bone-marrow processed by 72 and 96h
unstimulated cultures. Chromosomes were identified by G
banding. Aberrant chromosomes were examined by FISH, using
painting, region-specific, and/or centromeric probes.
Furthermore, we performed FISH technique with
(RB/LSID13S319/LSID13S25) and LSI 14q32/11q13 loci
probes. Karyotypes were designated according to the ISCN
criteria.
Results: We present cytogenetics results on 318 patients. An
abnormal karyotype was detected in 143 patients (45% of
evaluable patients): 17% of karyotypes were Pseudodyploid, 15%
Hyperdiploid and 11% Hypodiploid. Numerical and structural
abnormalities were found at the same time in the 45% of cases.
Monosomy of chromosome 13 was the most common numerical
abnormalities (22%), following of trisomy of chromosomes 5, 9
and 7 (17, 18 and 10% of cases). The most frequent recurrent
chromosomal anomalies were del(13)(q14) detected in 53
patients (37%), and 14q32 abnormalities detected in 22 patients
(15%), 15 of them as t(11;14)(q13;q32). The 45% of del(13)(q14)
and the 53% of t(11;14)(q13;q32) showed additional
abnormalities on karyotypes. FISH analysis showed del(13)(q14)
and t(11;14)(q13;q32) in a 42% (n=22) and in a 40% (n=6) of
cases that have been no detected by conventional cytogenetics.
The 43% (n=62) of clonal karyotypes were complex.
Chromosome 1 abnormalities represent the most frequent
aberration, observed in 31% of cases (n=45), implicated in
translocations with others chromosomes, detecting trisomies 1q
and monosomies 1p near with many chromosomal abnormalities.
FISH technique allowed more complete description of
karyotypes.
Conclusions: 1) The simultaneous analysis of conventional and
molecular cytogenetics allowed the detection of 45% clonal
karyotypes. 2) We detected del(13)(q14) and t(11;14)(q13;q32)
with many others chromosomics abnormalities in a high
frequency of cases (98%). 3) FISH analysis were more
perceptible for detection of del(13)(q14) and t(11;14)(q13;q32).
4) Chromosome 1 abnormalities represented the most frequent
cytogenetics anomalies. They could be secondary aberrations
associated to complex karyotypes, suggesting that chromosome 1
could be implicated in a more aggressibity of tumour. 5) The
great heterogeneity and complexity of newly diagnosed MM
karyotypes suggest that when the tumour is diagnosed it is
already in an advanced state of disease.
Our experience showed the necessity to carry out not only
specific FISH study but conventional cytogenetics in order to
permit: a) looking for cytogenetics abnormalities specifics of
MM, and b) establish the true role of recurrent anomalies:
del(13)(q14) and t(11;14), and will arrive to define which of them
or others, are primary or secondary abnormalities.
(Supported by Grant from Spanish FIS G03/136)
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Hierarchical clustering for the analysis of chromosome
aberration patterns in Multiple Myeloma.
Borja Sáez2, José I Martín-Subero1, Francisco Guillen3,
María D. Odero2, Felipe Prosper4, Juan C. Cigudosa5,
María J. Calasanz2, Reiner Siebert1
1. Institute of Human Genetics, University Hospital Schleswig-
Holstein Campus Kiel, Kiel, Germany. 2. Department of Genetics,
University of Navarra, Pamplona, Spain. 3. Department of Health
Science, Public University of Navarra, Pamplona, Spain. 4.
Department of Hematology, University Hospital, Pamplona, Spain
and 5. Cytogenetics Unit, Centro Nacional de Investigaciones
Oncológicas, Madrid, Spain;
The knowledge of chromosome aberration patterns in Multiple
Myeloma have been hampered by the low proportion of clonal
abnormalities found by conventional cytogenetics, and by the
high complexity of those cases with altered karyotypes.
Nevertheless, karyotypes of around 1000 cases have been
reported, and the main chromosomal features may be summarized
as follow: (1) abnormal clones appear to be divided into those
with modal chromosome numbers in the hypodiploid,
pseudodiploid and hyperdyploid range, being hyperdiploidy more
common (approximately 46-68%) than pseudo- or hypodiploidy.
The main numerical imbalances reported by conventional
cytogenetics are gains of chromosomes 3, 5, 7, 9, 11, 15 and 19,
and losses of 13, X (females), 14, 6q, 8, 16, and Y. (2) The
chromosome bands most commonly affected by structural
abnormalities are 13q14, mainly as deletions and 14q32, which is
involved in various translocations like t(11;14)(q23;q32) or
complex rearrangements with unidentified chromosomal partners.
Moreover, a prognostic implication has been postulated for some
of these aberrations, e.g 13q deletions have been described as an
adverse prognostic factor in MM. In order to better understand
the biological relevance of abnormal karyotypes in myeloma
cells, a systematic characterization of the karyotypic patterns is
required. Thus, the aim of our study was to identify distinct
subgroups of cytogenetic patterns among myeloma patients using
appropriate statistical approaches. A total of 276 myeloma cases,
all of them with abnormal karyotypes, were retrieved from our
own database and from previously published series. The presence
or absence of chromosomal aberrations by G-banding of all cases
were recorded, and those abnormalities present in more than 5%
of the cases entered the statistical analysis. A total of 43 variables
were included for the first approach. Chromosomal abnormalities
are asymmetrical binary data, thus, hierarchical clustering
analysis was performed. For these kind of variables the most
adequate method for computing distances is the Jaccard
coefficient or any of its variants like Dice or Sokal. For genetic
data usually two methods of hierarchical clustering are used,
average linkage or CAST (Cluster Affinity Search Technique).
As the last one is still experimental we have choosen average
linkage using three measures of distance, i.e. Jaccard´s, Dice´s
and Sokal´s coefficients. The three cluster trees resulting from
these analysis were analysed using the Stata and Clustan
software. Our preliminary results are in good concordance with
those recently published by Fonseca et al.(2003). Two major
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