2008 Barcelona - European Society of Human Genetics

Cancer genetics
ries.The identification of the JAK2-V617F mutation is an exciting new
discovery in the field of MPDs. This acquired mutation is characterized
by G→T nucleotide substitution at1849 position leading to valine to
phenylalanine substitution at amino acid position 617 (V617F) of the
JAK2 tyrosine kinase protein which results in constitutive JAK2 activation
that promotes proliferation . Objective:- To study the role and
frequency of the JAK2 mutation in myeloproliferative disorder patients .
Materials &Methods:- 60 MPD patients(30PV,16 IMF,14ET diagnosed
by bone marrow biopsy), 90 AML and 70 age& sex matched controls
were studied .DNA was extracted from peripheral blood mononuclear
cells and Allele Specific PCR was performed for V617F mutation.
Results:-Majority of PV patients (28/30;93 .4%) had V617F mutation
whereas the frequency of the mutation was lower in IMF and ET patients(7/16;
43 .7% and 7/14;50% respectively) .The mutated patients
had significantly higher mean haemoglobin and platelet count compared
to JAK2 wild type patients and controls .(p=00 .1) . Higher hematocrit
and splenomegaly was observed in V617F patients . Only one
AML patient and none of the 70 controls had VF617 mutation . conclusion:-
Thus presence of the mutation confers a proliferative and
survival advantage. Identification of the Val617Phe JAK2 mutation lays
the foundation for new approaches to the diagnosis specially PV and
classification. JAK2 can be new gene for the targeted therapy in myeloproliferative
disorders .
P04.118
importance of using JAK mutation in the diagnosis of
myeloproliferative diseases
P. Riedlová 1 , M. Brejcha 1 , L. Sokol 1,2 , J. Gumulec 3,1 , M. Kučerová 1 , M. Radina 1 ;
1 JG Mendel Cancer Centre, Nový Jičín, Czech Republic, 2 The University
Hospital L Pasteur, Košice, Slovakia, 3 The Faculty Hospital, Ostrava, Czech
Republic.
Chronic myeloproliferative disorders (CMPDs) are a group of various
clonal haematological malignat diseases including chronic myelogenous
leukemia (CML), polycythemia vera (PV), essential thrombocythemia
(ET) and chronic idiopathic myelofibrosis (CIMF). Except for
CML with a genetic abnormality the t(9,22), the molecular mechanisms
underlying the CMPDs have not been identified. Recently, several
research groups shown that a significant proportion of patients with
non-CML CMPDs have a missense somatic mutation in JAK2 gene
that substitues phenylalanine for valine at residue 617 (JAK2 V617F) .
JAK2 is a nonreceptor tyrosine kinase (TK) . Pseudokinase domain of
JAK2 in haematopoietic cells is responsible for the constitutive activation
of molecular signalling pathway and takes control of cell proliferation
in CMPDs .
DNA from 306 samples was isolated from peripheral blood granulocytes
in patients with CMPDs and genotyped for the JAK2 V617F
(G>T) mutation . To identify the mutation we used a real-time polymerase
chain reaction assay using fluorescent hybridization probes
and melting curve analysis . In a few cases that are JAK2 V617F negative
and have the non-CML CMPDs phenotype we detected novel mutations
in JAK2 exon 12 by direct sequencing . The detection of the
JAK2 mutations could be useful in the diagnostics of myeloproliferative
disease patients .
P04.119
Association between antral nodularity, severe gastritis, positive
serology, age, gender, ABO blood group and Helicobacter pylori
in children
T. Sabbi;
Pediatric Unit Belcolle Hospital, Viterbo, Italy.
Hp causes one of the most widespread infections worldwide . It is well
known that blood group antigens are related to the development of
peptic ulcer and gastric carcinoma .
Association between virulence factors of Hp, severe gastritis, age,
gender and ABO blood group .
25 patients underwent to esophagogastroduodenoscopy with antral biopsy
for a suspicious upper gastrointestinal disease . In all of them serum
sample were assayed for IgG antibodies to CagA and ABO blood
groups were determined .
19 children (76%) were Hp positive by histopathology and urease rapid
test . 15 of these 19 (79%) Hp positive patients were positive for CagA
serology . At endoscopic examination of the 19 infected children, hyperemia
of the gastric antrum was observed in 7 (37%) patients and antral
nodularity in 12 (63%) children . The histologic examination of all infected
patients showed an active and chronic gastritis . The children CagA
positive presented more intense hyperemia of gastric antrum, important
lymphoplasmacellular infiltrate and a degenerative and vacuolar
lesions of gastric epithelium . The 6 (24%) non infected patients, also
negative for CagA serology, had a normal gastric finding. As expected
from previous studies, we found that seropositivity for Hp increased
with age and the rate of Hp infection was not significantly different in
boys and girls. Similarly, Hp serological status was not significantly
different between subjects of different ABO blood groups .Despite epidemiological
evidence of increased peptic ulcer disease in ABO blood
group O subjects, we found no association between Hp infection and
ABO blood groups .
P04.120
Low Expression of ARHi contributes to Glial tumor
Development
S. Yakut 1 , R. Tuncer 2 , M. Berker 3 , E. Goksu 2 , I. Gurer 4 , G. Luleci 1 , S. B. Karauzum
1 ;
1 Akdeniz University, Faculty of Medicine, Department of Medical Biology and
Genetics, Antalya, Turkey, 2 Akdeniz University, Faculty of Medicine, Department
of Neurosurgery, Antalya, Turkey, 3 Hacettepe University, Faculty of Medicine,
Department of Neurosurgery, Ankara, Turkey, 4 Akdeniz University, Faculty of
Medicine, Department of Pathology, Antalya, Turkey.
Although the ARHI gene shows 60% sequence homology to the Ras
proto-oncogene, it is the first maternally imprinted tumor suppressor
gene identified in the Ras family. ARHI gene is constitutively expressed
from the paternal allele of normal breast, ovarian, heart, liver,
pancreas, tyroid, brain tissues and its expression is lost or markedly
downregulated primarily in breast, ovarian, pancreas and tyroid tumor
tissues . In this study, we investigated the mRNA expression, LOH (loss
of heterozygosity) and methylation analysis of ARHI gene in tumor and
peripheral blood samples of 21 cases with glial tumor, and 7 normal
brain tissue samples . Evaluation of the ARHI gene expression levels
by RT-PCR revealed reduction in 7 of 21 glial tumor samples (33 .3%) .
Analysis of LOH was performed by fragment analysis using 5 labeled
polymorphic markers specific for 1p31 region. LOH was detected in 2
of 21 cases (9 .5%) . Methylation status of CpG island II of 5 cases was
evaluated using COBRA (combined bisulfite restriction analysis) and
RFLP . Results indicated complete lack of hypermethylation in the CpG
island region II . Our results suggest that silencing of ARHI tumor suppressor
gene may play a role in the glial brain tumor development .
P04.121
Analysis of ATM case-control mutation screening data
D. T. Babikyan 1,2 , F. Lesueur 2 , C. Voegele 2 , M. Hashibe 2 , J. Hall 3 , G. B. Byrnes
4 , S. V. Tavtigian 2 ;
1 Center of Medical Genetics and Primary Health Care, Yerevan, Armenia,
2 International Agency for Research on Cancer, Lyon, France, 3 Institut Curie,
Orsay, France, 4 Centre for MEGA Epidemiology; University of Melbourne, Carlton,
Australia.
The susceptibility gene for Ataxia telengiectasia, ATM, recently has
been established as an intermediate-risk breast cancer (BC) susceptibility
gene . However, the answer to the question “what sort of sequence
variation in ATM confers increased risk of BC” has been controversial .
To address this question, we have pooled available ATM mutation
screening data and carried out a combined analysis of truncating variants,
splice junction variants, and rare missense substitutions (carrier
freq ≥ 1%). The analysis of rare missense substitutions was accomplished
by constructing a sufficiently informative protein multiple sequence
alignment of ATM from full-length sequences of seven species
and using a missense analysis program Align-GVGD with developed
new classifiers. Systematic case-control analysis of the missense substitutions
indipendantly provided evidence that ATM is a BC susceptibility
gene . We found that a combined analysis of truncating mutations,
splice junction mutations, and rare missense substitutions provides
stronger evidence that ATM is a BC susceptibility gene than simple
consideration of truncating plus splice junction variants alone . We also
found significant evidence of risk both in truncating plus splice junction
variants and in the in silico predicted highest-risk class of missense
substitutions . Taken together, these results led us to two conclusions:
(1) Careful analysis of missense substitutions by measuring risk attributable
to rare missense substitutions in a known or candidate suscep-