2008 Barcelona - European Society of Human Genetics

Cancer genetics
P04.094
Grafting outcome prediction by optimizing the protocol for
molecular monitoring of leukaemia patients
A. M. Constantinescu 1 , C. M. Constantinescu 1 , G. Girbea 1 , D. Iancu 1 , B.
Iancu 1 , E. Neagu 1 , A. Tanase 2 , S. Varady 3 , L. Barbarii 1 ;
1 National Institute of Legal Medicine, Bucharest, Romania, 2 Bone Transplant
Unit-Clinic of Fundeni Hospital, Bucharest, Romania, 3 Bone Marrow Transplant
Unit-Clinicof Fundeni Hospital, Bucharest, Romania.
Introduction . Disease relapse represents the major cause of treatment
failure after allogeneic hematopoietic stem cell transplantation (allo-
HSCT) . The aim of our study was to optimise the testing protocol for
establishing the chimeric status of patients performing allo-HSCT . We
compared the efficacy of two different multiplex STR-PCR kits, focusing
on their sensitivity and sensibility .
Method . DNA samples, provided by 17 patients and their haploidentical
donors were tested at various intervals in order to determine the
chimeric status . The samples were analysed using two different commercial
kits, each of them containing a set of 16 STRs (AmpFlSTR
Identifiler, Applied Biosystems; PowerPlex 16 System, Promega). For
each case, the most informative markers were selected and analysed
in dynamics. Artificial mixtures prepared from recipients and their donors
samples were analysed to set up reconstruction curves .
Results . Complete chimerism was detected for 15 patients, while 2
patients exhibited mixed profiles. Both commercial kits gave similar results
concerning the chimeric status . The reconstruction curves showed
a slightly higher sensitivity for the Identifiler kit, which quantified more
accurately the low concentrations of minor DNA component .
Conclusions . Our data indicate that both commercial STR-PCR kits
were able to establish an accurate chimeric status . A kit selection
should be performed in an objective manner, after analyzing its performances
regarding the typing sensitivity and sensibility for artificial
mixtures . Thus, precise monitoring of post-transplant hematopoietic
chimeric status becomes of outmost interest for the clinical follow-up
of leukaemia patients .
P04.095
tracking the natural history of leukaemic clone in mLL-driven
childhood acute leukaemias
J. Zuna 1 , T. Burjanivova 1 , E. Mejstrikova 1 , E. Fronkova 1 , Z. Zemanova 2 , K.
Muzikova 1 , C. Meyer 3 , S. W. Horsley 4 , L. Kearney 4 , H. Ptoszkova 5 , D. Mendelova
6 , R. Marschalek 3 , O. Hrusak 1 , J. Stary 1 , M. Greaves 4 , J. Trka 1 ;
1 CLIP, Charles University Prague, 2nd Medical School, Prague 5, Czech
Republic, 2 Center of Oncocytogenetics, Institute of Clinical Biochemistry and
Laboratory Diagnostics, General University Hospital and 1st Medical School,
Charles University, Prague, Czech Republic, 3 Institute of Pharmaceutical Biology/DCAL,
JWG University of Frankfurt, Frankfurt/Main, Germany, 4 Institute of
Cancer Research, Sutton, Surrey, United Kingdom, 5 University Hospital Ostrava,
Ostrava, Czech Republic, 6 University Hospital Brno, Brno, Czech Republic.
We and others have previously documented prenatal origin of paediatric
acute lymphoblastic leukaemias (ALL) by demonstrating identical
clonal changes in monozygotic twins/triplets and/or backtracking
of the (pre)leukaemic clone to neonatal blood spots or cord blood of
patients . We have also detected the cells of preleukaemic clone in the
cord blood of healthy newborns never developing leukaemia . However,
the evolution of definitive leukaemic clone remains largely unclear.
Secondary ALL developing during leukaemia treatment represents a
unique chance to follow this process . We analysed two cases of treatment-related
ALL involving notorious oncogenic transcription factor
MLL . In both patients, cells bearing MLL fusion (MLL/FOXO3A, MLL/
MAML2) appeared in bone marrow long before the definitive leukaemic
clone was identified: 20 and 24 months, respectively. Moreover, in
both cases, FISH and/or qRT-PCR showed this fusion in a substantial
proportion (10%-90%) of marrow cells with morphologically intact differentiation
during the preleukaemic phase . In the MLL/FOXO3A case
we were able to document its presence in lymphoid as well as myeloid
lineage, thus indicating the fusion arose in a multipotent progenitor .
In both cases, definitive lymphoblastic leukaemic clones arose only
shortly before relapse . Comparison by SNP-array revealed a 10Mb
region of amplification on 19q13.32 in one of the leukaemic samples,
absent in the preleukaemic phase . Taken together, we document a
striking sequence of events including covert protracted preleukaemic
phase characterised by dominant MLL-fusion with intact differentiation
and subsequent acquisition of secondary genetic abnormality (proven
in one case) . These data provide unique insight into the MLL-driven
leukaemogenesis .
Support: MSM21620813
P04.096
Amplification of hTERC and hTERT genes in leukemic cells
detected by fluorescent in situ hybridisation (FISH)
A. Erjavec- Skerget, A. Zagorac, N. Kokalj Vokac;
University Clinical Centre, Maribor, Slovenia.
The high level of genomic amplification of the human telomerase
genes hTERC and hTERT, which maps to chromosome bands 3q26
and 5p15, was determined in different human cancer cells . We represent
the results of the fluorescent in situ hybridisation (FISH) analysis
with both locus specific probes on cell cultures from bone marrow of 35
patients with acute malignant blood disease . Among them 32 patients
were with non-lymphoid and 3 with lymphoid type of malignancy . Bone
marrow cells were first karyotyped by standard cytogenetic analysis.
FISH revealed a low grade amplifications of hTERC gene at 4/35 patients
and a low grade of the hTERT amplifications at 5/35 patients.
The comparison of the karyotypes and the FISH results by each patient
reveals low grade amplification of hTERC gene only at one patient
with previously determined complex karyotype. We didn’t confirm
any amplification of hTERT gene. Our results, based on comparison of
the results derived by FISH and karyotyping, show that the hTERC and
the hTERT amplification are not so common in patients with malignant
blood disease as in other types of cancers .
P04.097
mRP1 polymorphisms (t2684c, c2007t, c2012t, and c2665t)
are not associated with multidrug resistance in Leukemic
patients
F. Mahjoubi, S. Akbari, F. Moshyree;
NIGEB, Tehran, Islamic Republic of Iran.
One of the major problems in treating cancer patients is that cancer
cells can evolve in drug resistance . Because this form is resistant to
multiple anticancer drugs, so called multidrug resistance (MDR), the
mode of resistance must be nonspecific, involving drug-efflux transporters
. One of the most extensively studied genes involved in MDR is
multidrug resistance protein 1(MRP1) . We have investigated the possible
association between the expression level of MRP1 and occurrence
of MDR in 111 patients with acute leukemia (which included 52
patients with acute myelogenous leukemia and 59 patients with acute
lymphoblastic leukemia) . mRNA level of MRP1 had been determined
by quantitative real time RT-PCR and compared to the type of response
to chemotherapy . We found that high expression of MRP1 was
associated with poor clinical outcome in both AML and ALL patients .
In our previous studied we had shown that the increase in MRP1 gene
dosage was not responsible for the upregulation of MRP1 expression
in leukemic patients .
Therefore, we aimed to investigate the effect of MRP1 polymorphisms
on the expression level of it . The T2684C, C2007T, C2012T, and
C2665T polymorphisms were genotyped in all the patients and control
group . There was no effect of a particular genotype on the expression
level of the MRP1 gene . This could show the lack of dependency of any
of these genotypes on the chemosensivity in this group of patients .
P04.098
study of the effect of mRP1 gene polymorphisms on its mRNA
expression in patients with acute leukemic
S. Rezvany 1,2 , F. Mahjoubi 1 , K. Alimoghaddam 3 ;
1 NIGEB, Tehran, Islamic Republic of Iran, 2 Azad University, Tehran, Islamic
Republic of Iran, 3 3) Hematology, Oncology and BMT Research Center, Sharyattee
Hospital, Tehran, Iran, Tehran, Islamic Republic of Iran.
Principle: One of the major problems in treating cancer patients is that
cancer cells can evolve in drug resistance . Because this form is resistant
to multiple anticancer drugs, so called multidrug resistance ( MDR
) , the mode of resistance must be nonspecific, involving drug-efflux
transporters . One of the most extensively studied genes involved in
MDR is multidrug resistance protein 1(MRP1) .
We aimed to investigate the possible association expression level of
MRP1 and occurrence of MDR in leukemic patients wished to test the
hypothesis that MRP1 polymorphisms would be predictive of MDR in
patients with acute leukemia .