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

Molecular and biochemical basis of disease
the tested families MLPA showed no pick for exon 23 on the electrophoregrams,
whish supposed deletion of this exon. A single PCR amplification
of exon 23 showed the exon presence in the patient. Further
sequencing analysis revealed a point mutation generating stop codon
in exon 23 - c.2991C>G, p.Tyr997X. The nucleotide change affects
the place of hybridization of the exon 23 specific MLPA probe, which
is the reason for absence of exon 23 on the electrophoregrams. The
patient was severely affected by Duchenne-type muscular dystrophy.
Both patient’s mother and sister were found to be carriers of the mutation
p.Tyr997X. Our experience in MLPA analysis stressed upon the
fact that single exon deletions should be interpreted with caution and
should be proved by alternative methods. In some cases it is possible
to detect point mutations and polymorphisms by MLPA analysis.
P0802. Screening for subtelomeric abnormalities in patients with
idiopahtic mental retardation by MLPA
D. S. Iancu 1 , C. Rusu 2 , E. Neagu 1 , G. Girbea 1 , A. Constantinescu 1 , C. Constantinescu
1 , C. Scrypnik 3 , V. Bica 4 , L. Barbarii 1 ;
1 National Institute of Legal Medicine, Bucharest, Romania, 2 University of Medicine
and Pharmacy, Iasi, Romania, 3 University of Medicine, Oradea, Romania,
4 “Alfred Rusescu” Children Hospital, Bucharest, Romania.
Recent studies ascertained that 5 to 10% of mental retardations are
due to mutations in the subtelomeric regions. Knowing the mutational
pattern is of major importance for genetic counseling. We have studied
the subtelomeric rearrangements using a MLPA assay in a series of
clinically selected patients with mental retardation and negative chromosomal
analysis. The study was initiated in the framework of a multicentric
national research program. The MLPA probes included in the
commercial kits allowed us to scan all the subtelomeric regions in two
PCR reactions. The amplicons were analyzed on a 3100 Avant ABI
Genetic Analyzer. We investigated 123 DNA samples and assessed
the location of deletions and duplications. The MLPA screen revealed
mutations in 6% of cases (on the short arms of chromosomes 1, 7
and 18). Except one, all the mutations were deletions and no multiple
deletions were detected. One case revealed a double subtelomeric
mutational pattern, consisting of a 7q deletion associated with 9q duplication.
The MLPA method proved to be easy to handle, accurate and
highly reproducible. For the patients carrying subtelomeric rearrangements,
further investigations (FISH) are planned in order to confirm the
mutation and DNA samples from their relative are collected.
P0803. First case of Gamma-Thalassemia
C. Badens1 , K. Gonnet1 , F. Merono1 , N. Bonello1 , N. Levy1 , I. Thuret2 ;
1 2 Department of Genetics, Hospital La Timone, Marseille, France, Pediatric
Hematology, Hospital La Timone, Marseille, France.
Numerous deletional Thalassemia have been reported, involving one
or several globin genes in combination. However, deletions specifically
targetted on the fetal β-like genes have never been reported so far,
likely due to a fetal lethal phenotype induced by homozygous mutations
in these genes. By contrast, heterozygosity is likely clinically silent.
Here, we report on the observation of a fetal β-like genes deletion
that we detected because it was located in Cis of a Sickle Cell β-globin
gene.
The proband is a newborn diagnosed at birth as having Sickle Cell
Anemia (SCA) in the course of neonatal screening. During the first
consultation, at 6 weeks of age, haemoglobin analysis revealed the
following Hb rates : HbF 55%, HbS 27% and HbA 15% . Molecular
analysis of the β-globin gene showed, as a single defect, heterozygosity
for the prevalent sickle cell mutation. During the course of evolution,
the level of HbA raised slowly to a normal value and, finally, a typical
profile for HbS carrier was observed at 8 month of age.
In order to further explore this peculiar phenotype, the whole β-globin
locus was explored by means of MLPA technical procedures and allowed
to evidence a heterozygous deletion of the fetal genes, A γ and
G γ-globin. We conclude that a deletion of the fetal genes have led to a
premature switch on the adult βS-gene and to SCA profile at birth. This
is the first case of γ-thalassemia ever reported, representing a pitfall in
neonatal screening of SCA.
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P0804. A Retrospective Analysis of Patients Previously
Tested For Gene Polymorphisms Implicated In Influencing
Susceptibility To Thrombosis In A Reference Center in Izmir/
Turkey
F. Ozkinay 1,2 , H. Onay 1 , G. Itirli 1,3 , C. Gunduz 4 , M. Kayikcioglu 5 , E. Kumral 6 , O.
Cogulu 1,2 , H. Akin 1 , C. Ozkinay 1 ;
1 Ege University, Faculty of Medicine, Department of Medical Genetics, Izmir,
Turkey, 2 Ege University, Faculty of Medicine, Department of Pediatrics, Izmir,
Turkey, 3 Ege University, Department of Biotechnology, Izmir, Turkey, 4 Ege University,
Faculty of Medicine, Department of Medical Biology, Izmir, Turkey, 5 Ege
University, Faculty of Medicine, Department of Cardiology, Izmir, Turkey, 6 Ege
University, Faculty of Medicine, Department of Neurology, Izmir, Turkey.
Arterial and venous thromboembolism is one of the most common
diseases affecting populations throughout the world. Recently the
polymorphisms found in a number of genes which play a role in the
thromboembolic processes have been reported to be risk factors for
thromboembolism.
For two years our department has made use of a strip test (CVD StripAssay,
ViennaLab, Austria) detecting the following gene polymorphisms.
These polymorphisms; FV R506Q(Leiden), FV H1299R, Prothrombin
G20210A, Factor XIII V34L, ß-Fibrinogen -455 G-A, PAI-1
4G/5G, GPIIIa L33P(HPA-1), MTHFR C677T, MTHFR A1298C, ACE
I/D, Apo B R3500Q,Apo E2/E3/E4.
In this study we retrospectively investigated the referral indications and
the frequencies of the polymorphisms in the children and adult patients
tested using this CVD stripassay at the Ege University Medical
Genetics Department. The frequencies of the polymorphisms found in
patients were compared to the frequencies of the liver transplantation
donors who were routinely tested before transplantation.
During the two year period, 426 patients (146 children, 280 adults)
were tested using the CVD strip test. The majority of patients in the
adult group were referred to our department with indications of cardiovascular
and/or cerebrovascular diseases from the cardiology, neurology
and internal medicine departments. The frequencies of Factor V
(H1299R) beta fibrinogen(455G-A) and MTHFR (C677T) were found
to be significantly higher in patients having cardiovascular and/or cerebrovascular
diseases compared to the frequencies found in control
group (p