European Human Genetics Conference 2007 June 16 – 19, 2007 ...

Cytogenetics
22 leading to the formation of bcr/abl fusion gene.
Disease relapse still represents the major cause of treatment failure in
patients with CML, following bone marrow transplantation. Thus, the
early detection of minimal residual disease (MRD) has relevant therapeutic
implications.
Sequential cytogenetic analysis was done using standard methods in
bone marrow samples from10 patients with CML. Further dual colour
Fluorescence In Situ Hybridisation (FISH) analysis was done to assess
molecular response using bcr/abl. The chimerism pattern and bcr-abl
status were studied. The results of present study show that bone marrow
transplantation induce both cytogenetic and molecular response
in a significant proportion of CML thereby improving their prognosis
and survival. The importance of using FISH analysis on interphase nuclei
and poor-spread metaphases that cannot be analyzed using conventional
cytogenetics was also highlighted. Thus the present study
stresses on the need for sequential cytogenetic and molecular analysis
in diagnosis and disease management of myeloid leukemias.
P0316. Molecular cytogenetic characterization of der (9)
deletions in a case of Philadelphia-negative chronic myeloid
leukemia
A. Bennour 1 , H. Sennana 1 , H. El Omri 2 , S. Mougou 1 , A. Khelif 2 , A. Saad 1 ;
1 Service de cytogenetique et de biologie de la reproduction CHU Farhat Hached,
Sousse, Tunisia, 2 Service d’hématologie CHU Farhat Hached, Sousse,
Tunisia.
About 95% of the patients with chronic myeloid leukemia(CML) have
a Philadelphia chromosome resulting from a reciprocal translocation
between bands 9q34 and 22q11.2 that juxtaposes the 3’ABL
gene to the 5’BCR gene. Recent studies using fluorescence in situ
hybridization(FISH) have reported deletions due to the loss of sequences
proximal to chromosome 9 breakpoint or distal to chromosome
22 breakpoint. In this paper we report on a detailed molecular
cytogenetic characterization carrying der(9) deletions in an apparently
Philadelphia negative CML patient.
FISH experiments were carried out in bone marrow sample from CML
patient at diagnosis. A detailed study using conventional cytogenetic
and FISH analysis was done using ES-FISHprobes, Whole chromosomes
painting and BAC in order to elucidate the mechanism of 9q
deletion.
ES-FISH probes disclosed the BCR/ABL fusion gene on
der(22)chromosome and deletion of signal on der(9) chromosome.
Whole chromosomes painting revealed deletion of ABL/BCR fusion
gene on der(9).
Using FISH with an appropriate set of BAC probes located proximally
to BCR and ABL genes we have characterized the deleted region on
both chromosomes 9 and 22.
Our study shows that the location of the deleted sequences was downstream
of the BCR breakpoint and upstream of ABL gene and that genomic
microdeletions were concomitant with t(9;22) rearrangements.
FISH analysis allowed not only the identification of chromosome rearrangements
that could not otherwise be detected by conventional
banding procedures, but also the recognition of 5’ABL and 3’BCR deletions
which could carry with it a poor prognosis that indicates rapid
disease progression in CML.
P0317. Prenatal diagnosis of an unexpected de novo complex
chromosomal rearrangement.
S. Jaillard 1 , C. Henry 1 , C. Dubourg 2,3 , M. Durou 2 , L. Loeuillet 4 , J. Milon 5 , E.
Bauville 6 , J. Mosser 3 , V. David 2,3 , L. Pasquier 7 , J. Lucas 1 ;
1 Laboratoire de Cytogénétique, CHU Rennes, France, 2 Laboratoire de Génétique
Moléculaire, CHU Rennes, France, 3 UMR 6061 CNRS, Rennes, France,
4 Département d’Anatomie et Cytologie Pathologiques, CHU Rennes, France,
5 Département de Radiologie et Imagerie Médicale, CHU Rennes, France, 6 Département
d’Obstétrique, Gynécologie et Médecine de la Reproduction, CHU
Rennes, France, 7 Service de Génétique Médicale, CHU Rennes, France.
We report a prenatal diagnosis of de novo apparently balanced reciprocal
translocation t(2;10)(q?24;p?15.1) which turned out to be a complex
event after molecular cytogenetic analysis. Fetal conventional
R-banded karyotype was performed on amniocytes at 32 weeks gestation
because of sonographic findings: IUGR, single umbilical artery
and arachnoid cyst of the posterior fossa. To precise the breakpoint on
chromosome 10, molecular cytogenetic analysis by FISH was used
with a 10p14 band-specific probe: unexpectedly, the signal wasn’t
10
localized on the derivative chromosome 2 but on a chromosome 5.
Then, hybridization of whole chromosome painting probes WCP 2, 5
and 10 showed an increasing complexity of the rearrangement leading
to complex derivative chromosomes: der(2) and der(10) were found
to have segments from the three chromosomes as a consequence of
terminal exchanges and insertions. Subtelomeric probes of chromosomes
2, 5 and 10 revealed a terminal deletion of the long arm of chromosome
2 (2qter). Finally, this complex chromosomal rearrangement
seemed to involve 3 chromosomes and 5 breakpoints. The pregnancy
was terminated and the fetopathological examination confirmed prenatal
ultrasound report and showed additional congenital anomalies:
facial dysmorphism, heart defects, corpus callosum and cerebellum
abnormalities. 2qter deletions are associated with variable clinical features
and in our case, the 2qter microdeletion should be responsible
for the phenotype. Array-CGH will be performed in order to precise the
size of the 2qter deletion and to screen for additional cryptic genomic
imbalances near the breakpoints or elsewhere.
P0318. Cytogenetic and Molecular studies in Egyptian patients
with congenital heart defects, A pilot study.
I. M. R. Hussein 1 , N. Helmy 1 , M. El-Rubi 1 , H. A. Hussein 1 , A. El-Gerzawy 1 , A.
Ahmad 1 , A. Fayez 1 , N. Abdel-Rahman 2 ;
1 National Research Centre, Cairo, Egypt, 2 Cairo University, Cairo, Egypt.
Objective: To analyze the frequency of chromosomal anomalies and
molecular defects in Egyptian patients with congenital heart defects
(CHD). Patients and Methods: The study included 34 patients with
congenital heart defects; confirmation of the heart defect was accomplished
by echocardiography and/ or cardiac catheterization.
Chromosomal analysis was done using GTG-banding and FISH techniques.
Mutation detection in transcription factor GATA4 and NKX2.5
was done using PCR/ SSCP and DNA sequencing. Results: Patients
were classified into isolated heart defects (n=21) and CHD associated
with other congenital malformations (n-13). Associated malformations
were: (Down syndrome (2), Aarskog Scott S. (1), velocardiofacial S.
(2 sibs), Russel Silver (1), hand anomaly (2), trisomy 18 (1); and dysmorphic
(4). Chromosomal anomalies were found in 9/30 patients (30
%). They were: Trisomy 21 [47, XY,+21 (1); 46, XX, t(21;21) (1)]; 47,
XX+13 (1); 47,XX,+18 (1); 46, XY, t (14; 18) (q11.2; p11.2) (1); 47, XY +
mar (mat.) (1); 46, XX del 11q 23.3- qter (2 sibs); 46, XX, dup13q33-34
(1). DNA sequencing of NKX2.5 gene in 15 patients with isolated ASD
revealed normal sequence in all cases. Sequencing of GATA4 gene
in 12 patients with Fallot’s tetralogy has shown polymorphism in exon
6 at nucleotide 53423 (A-G) in 2 patients. Conclusion: Chromosomal
analysis of patients with heart defects and other congenital anomalies
has a great impact on diagnosis, prognosis and genetic counseling of
patients. The mutations in isolated defects might be mainly of somatic
origin that could not be observed in peripheral blood lymphocytes.
P0319. A case with Prader-Willi phenotype and a de novo
t(2;15)(q31;p11)
T. Cora 1 , H. Acar 1 , A. Kalaycı 1 , E. Atabek 2 ;
1 Dept. of Medical Genetics,Meram Medical Faculty, Selcuk Unıversıty, Konya,
Turkey, 2 Dept. of Pediatics, Meram Medical Faculty, Selcuk Unıversıty, Konya,
Turkey.
In recent years, the spectrum of available methods for the characterization
of chromosomal rearrangement has dramatically increased. Thus,
the correlation between phenotype and genotype has been done accurately.
In the present report, we describe the clinical and cytogenetic
findings of a patient with 46,XX,t(2;15)(q31;p11). A 2-year-old girl with a
clinical feature show Prader-Willi phenotype. The patient and her family
were studied by the conventional (GTG, NOR and C-bandings) and
molecular cytogenetic (for PW region) techniques. The results showed
the proband with a balanced de novo karyotype 46,XX,t(2;15)(q31;p11)
by using GTG-banding. Clinical and genetic findings were compared to
the other patients published in the literature.