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

Cytogenetics
Within the same metaphase hemimethylated and hypomethylated
homologues were represented in different combinations, which may
result from random segregation of hypomethylated, undermethylated
and methylated chromatids in daughter blastomeres. Band-specific
DNA methylation pattern, typical for fetal tissues and adult lymphocytes,
was obvious in all metaphases since blastocyst stage. This is
a pioneer study in human preimplantation metaphase cytogenetics.
Supported by CRDF&RFBR.
P0344. Late cytogenetic effects of radiation expressed in human
cells following Chernobyl accident
M. A. Pilinskaya, S. S. Dibskiy, O. V. Shemetun, Y. B. Dibskaya, O. A. Talan,
L. R. Pedan;
Research Centre of Radiation Medicine, Kijiv, Ukraine.
We performed an evaluation of late cytogenetic consequences following
the Chernobyl accident of human radiation exposure. These include
hidden, delayed, and transmissible chromosome instability and
“bystander effect”. For the investigation of radiation-induced chromosome
instability two methods had been applied - provocative mutagenesis
assay (G 1 -dimatyph or G 2 -bleomycin tests used for persons
differed on absorbed radiation doses) and two-termed (during 48 and
144 hours) cultivation of peripheral blood lymphocytes received from
children born to irradiated parents. In children that lived in a region
contaminated by 137 Cs as well as in clean-up workers with low radiation
doses «adaptive response» had been detected; in high-doses patients
recovered from acute radiation sickness increased chromosome
sensitivity (hidden chromosome instability?) to additional mutagenic
exposure was revealed. In progeny of irradiated parents an increased
frequency of chromosome aberrations (single fragments and abnormal
monocentrics) was established especially in long-termed cultures.
Induction of chromatid breaks confirmed possibility of expression of
delayed chromosome instability in subsequent mitosis; appearance of
stable aberrations can be considered as a biomarker of transmissible
chromosome instability. In the model system proposed by us - “mixed
human lymphocytes culture” consisted of cells differed by cytogenetic
sex markers - interaction between X-irradiated in vitro (in doses 250
and 1000 mGy) and intact cells was discovered. A difference between
the spectrum of aberrations in exposed and intact cells was established
- in targeted cells specific cytogenetic markers of irradiation
dominated, in “bystander” cells chromatid types of aberrations (chromatid
breaks and terminal chromosome deletions - cytogenetic indicators
of chromosome instability) were mainly induced.
P0345. An apparently balanced complex chromosome
rearrangement involving chromosomes 1, 10, and 14 in a man
with infertility
B. Bajelan 1 , F. Mahjoub 2 , S. Karymee 1 , M. Khaleghian 1 , S. Tootain 1 , T. Tavakol
1 , Z. Saltanatpour 1 , M. Akbari 3 ;
1 Akbari Medical Genetics Laboratory, Tehran, Iran, Tehran, Islamic Republic of
Iran, 2 Akbari Medical Genetics Laboratory, Tehran, Iran&nrcgeb, Tehran, Islamic
Republic of Iran, 3 Akbari Medical Genetics Laboratory, Tehran, Iran &Department
of Genetic, Faculty of Medicine, Tarbiat Modaress University, Tehran,
Iran, Tehran, Islamic Republic of Iran.
In study investigation was on Congenital complex chromosomal rearrangement
compatible (CCR) with life is rare in man. We describe
a complex and unique apparently balanced translocation involving
chromosomes 1, 10, and 14 with 3 breakpoints, in a patient who was
referred to our clinic because of infertility. Conventional karyotyping
identified a complex rearrangement involving 3 breakpoints: chromosome
1q21.2, 10q21.1, 14q22.
The relationship between this apparently balanced and complex rearrangements
and possibly produced unbalanced gametes responsible
for high reproductive failure is discussed. The relationship between
this apparently balanced and complex rearrangements and possibly
produced unbalanced gametes responsible for high reproductive failure
is discussed.
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P0346. The shape, length and banded structure of chromosome
5 in interphase of HeLa cells
U. Claussen1 , K. Sperling2 , J. Claussen2 ;
1 2 Institute of Human Genetics, Jena, Germany, Institute of Human Genetics,
Berlin, Germany.
In contrast to metaphase chromosomes, little is known about the
shape, length and the banding pattern of human interphase chromosomes
mainly due to technical problems in visualizing interphase chromosomes.
We analyzed the structure of chromosome 5 in interphase
nuclei using high-resolution multicolor banding (MCB), which paints the
total shape of chromosomes and creates a DNA-mediated, chromosome
region-specific, pseudo-colored banding pattern and allows the
identification of telomeres and the measurement of the length of chromosomes.
The investigations were performed on HeLa cells arrested
at different phases of the cell cycle. The results show that the shape,
length and banding pattern of interphase chromosomes of HeLa cells
are similar to those of the corresponding metaphase chromosomes at
all stages of the cell cycle. The length of the chromosome axis of flattened
interphase chromosomes is 13.9µm (+/- 4.1) and comparable to
that of a metaphase chromosomes. The MCB pattern also allows the
detection and characterization of chromosome aberrations which may
be of fundamental importance in establishing chromosome analyses in
non-dividing cells. Consequently, we strongly recommend to reassess
the concept of chromosome condensation during mitosis and to replace
it by the new concept of a hierarchically organized chromosome
region specific protein swelling based on protonation and hydration
thereafter.
P0347. Cytogenetic, molecular and clinical characterization on
an interstitial deletion of chromosome region 18q21 - a case
report
N. M. P. O. Teles, M. Rocha, M. Martins, S. Pires, M. M. Freitas, J. Ribeiro, M.
L. Rodrigues, P. Jorge, R. Santos, M. Pinto;
Instituto de Genética Médica Jacinto Magalhães, Porto, Portugal.
The 18q- syndrome (MIM 601808) originally described in 1984 is a
relatively frequent chromosomal cytogenetic event normally resulting
from a terminal deletion that may include bands from 18q21.1→qter
and has a characteristic phenotype (midfacial hypoplasia, prominent
antihelix and whorl digital pattern). Interstitial deletions involving the
same region are rare events and include variable phenotypes, from
moderate development delay and craniofacial asymmetry (Engelen et.
al , 2003) to profound mental retardation but no life-threatening, unspecific
malformations (Wilson et al., 1979).
The authors present the clinical description, cytogenetic studies and
molecular findings of a male patient age 34 with severe mental retardation
and marked dysmorphic features: plagiocephaly; asymetric
face, with midfacial hypoplasia and prominent antihelix. High resolution
GTG banding karyotypes of the proband and parents revealed a
“de novo” del(18q21.2→18q21.3) in the proband. Cytogenetic molecular
techniques (FISH) excluded the involvement of any other chromosome
and MLPA probes within bands 18q21 and 18q23 (kit P095 Aneuploidy)
allowed us to redefine the bands involved and will hopefully
be useful to improve the phenotype/genotype correlation in patients
with interstitial 18q deletions.
The authors compare the present case with the ones previously described
in the literature and emphasize the importance of high resolution
GTG banding in the characterization of dysmorphic/psychomotor
delay syndromes and of making accurate clinical descriptions of the
patients to contribute to syndrome clarifications.
P0348. A patient with Williams Beuren syndrome and inv dup(15)
V. Petix1 , E. Bevilacqua1 , A. Fabretto1 , D. Gambel Benussi1 , E. Lenzini2 , V.
Pecile1 ;
1 2 S.C. Genetica Medica, I.R.C.C.S. Burlo Garofolo, Trieste, Italy, Dipartimento
di Pediatria, Università degli Studi di Padova, Padova, Italy.
In the literature, very few reports describe the concomitant presence of
2 anomalies leading to 2 different genetic syndromes. The contribution
of each anomaly to the phenotype is still unclear. This report describes
a case presenting contemporarily a Williams-Beuren Syndrome (WBS)
and an inv dup(15) syndrome.
WBS is a microdeletion syndrome characterized by typical cardiovascular
defects, facial dysmorphisms, connective tissue abnormalities,
mild mental retardation, specific cognitive profile, endocrine abnor-