2009 Vienna - European Society of Human Genetics

Cancer genetics
P06.107
Large BRcA1 genomic rearrangements in czech high-risk
breast-ovarian cancer families
M. Lukesova, E. Machackova, J. Hazova, P. Vasickova, M. Navratilova, L.
Foretova;
Masaryk Memorial Cancer Institute, Brno, Czech Republic, Brno, Czech Republic.
BRCA1 and BRCA2 germline mutations predispose to breast and
ovarian cancer. In addition to point mutations, small insertions and
deletions there are also large genomic rearrangements (LGRs) in
BRCA1/2 genes. For detection of these LGRs we used the multiplex
ligation-dependent probe amplification (MLPA). We have screened for
LGRs about 1100 unrelated patients with familial breast and/or ovarian
cancer in whom a deleterious mutation in BRCA1 and BRCA2 was not
detected. Characterization of the LGRs was carried out by performing
long-range PCR followed by sequencing.
We identified 34 (3,1%) patients with 11 different LGRs (all of them in
BRCA1 gene), including a complete deletion of BRCA1 gene. Existence
of this entire BRCA1 gene deletion was proved by using two alternative
MLPA kits (SALSA P002B and P087) that have different localization
of ligation probes. In additon - during High Resolution Melting
analysis of all BRCA1 gene exons of this patient none polymorphism
has been detected what shows an evidence of loss of heterozygosity.
LGRs make a significant contribution to the whole amount of disease
causing mutations. In our opinion detection of LGRs in BRCA1 gene
should be a part of routine screening. No LGRs in BRCA2 gene were
detected yet.
Supported by the Ministry of Health of the Czech Republic: Grant MZ-
0MOU2005
P06.108
High risk BRcA1 and BRcA2 alleles in Estonia; family with a
rare BRcA2 mutation
N. Tõnisson 1,2 , P. Laidre 1 , I. Lind 1,3 , M. Kõiv 1 , K. Sak 3 , A. Metspalu 2,4 , K. Õunap
1,5 ;
1 Tartu University Hospital, Tartu, Estonia, 2 University of Tartu/Estonian Biocentre,
Tartu, Estonia, 3 Asper Biotech, Ltd., Tartu, Estonia, 4 Estonian Genome
Project, Tartu, Estonia, 5 University of Tartu, Tartu, Estonia.
We have lately established a hereditary breast and ovarian cancer
counselling and genetic testing service. The testing is two-phase. At
first, cost-efficient arrayed primer extension (APEX) chip is used for
mutation screening of referring persons with personal or family history
of breast and ovarian cancer. If no mutations are found, full sequencing
of BRCA1 and BRCA2 genes is performed in high-risk patients.
By February 2009, 62 persons had been counselled and tested in
the Dept. of Genetics, Tartu University Hospital, Estonia. 12 (19.4%)
had high-risk alleles present in BRCA1 and BRCA2 genes. From nine
high-risk alleles known to date in Estonia, five were found: c.300T>G
(p.C61G), c.1186delA, c.4154delA, c.5382insC in BRCA1 gene and
c.9168insA in BRCA2 gene.
We would introduce a family with rare c.9168insA BRCA2 mutation.
According to Breast Cancer Information Core database, this has been
formerly reported only once. A woman with breast cancer diagnosed
at age 66 was counselled. Her sister had got the same diagnosis at 40
years age and ovarian cancer at 45 years; she had died at 50. Their
father had fell ill with breast cancer at 87. The father and his daughter
had both the c.9168insA BRCA2 mutation. The daughters` three
descendants were examined and one of them was found to be the
mutation carrier. The family is ethnic Russian, originating from Moscow
Oblast.
Genetic services are essential for efficient management of hereditary
cancer. Sequencing results will be further used for updating the chip
according to local profile of risk alleles.
P06.109
screening for BRCA1/2 gene large rearrangements in 260
spanish hereditary breast cancer cases: high occurrence of
deletions in the BRCA gene in male breast cancer patients
A. Lasa 1 , J. Juan 1 , M. Cornet 1 , T. Ramón y Cajal 2 , S. Gutierrez 3 , E. del Rio 1 , O.
Diez 3,4 , M. Baiget 1 ;
1 Servei de Genètica - Hospital Sant Pau, Barcelona, Spain, 2 Servei de Oncologia
- Hospital Sant Pau, Barcelona, Spain, 3 Vall d’Hebron, Institut d’Oncologia,
Barcelona, Spain, 4 Hospital Universitari Vall d´Hebron, Barcelona, Spain.
BRCA1 and BRCA2 germ-line mutations predispose to breast and
ovarian cancer. The multiplex ligation-dependent probe amplification
(MLPA) is a method for detecting gross deletions or duplications of
DNA sequences, aberrations which are commonly overlooked by standard
diagnostic analysis.
To determine the incidence of large rearrangements in cancer predisposition
genes BRCA1 and BRCA2 we have analyzed both genes in
260 individuals from hereditary breast/ovarian cancer families without
deleterious point mutations.
A total of 8 pathogenic rearrangements in the BRCAs genes were
found, accounting for 3.1% of the cases. In two patients from families
with breast and ovarian cancer, one deletion affecting the entire
BRCA1 gene was identified (0.8% of mutation-negative BRCA cases).
For BRCA2 six deletions were detected (2.3%): del ex2, del ex10-12
and del ex15-16, this last one observed in four cases. Interestingly,
deletions involving exons 15 and 16 seem to be frequent in our series
accounting for 1.5% of all the rearrangements. It is important to note
that four of these six cases with BRCA2 deletions were from families
with co occurrence of female breast and male breast cancer.
P06.110
ten years of BRCA and BRCA molecular diagnosis in
switzerland
P. Maillet, G. Benais-Pont, V. Sciretta, C. Souverain, B. Pardo, M. Khoshbeen-
Boudal, A. P. Sappino;
Laboratory of Molecular Oncology, Geneva University Hospitals, Geneva, Switzerland.
Since 1999, our ISO certified laboratory is the Swiss reference laboratory
for BRCA1 and BRCA2 genes analysis. We received samples
from physicians involved in the Swiss (SAKK) network for cancer predisposition
testing and counselling. Here, we describe for the first time
10 years of BRCA1 and BRCA2 genes molecular diagnosis in 1130
individuals from 900 distinct families from Switzerland with a personal
and family history suggestive of genetic predisposition to breast/ovarian
cancer.
Patients from high-risk families recruited from oncogenetics consultations
in Switzerland (especially Geneva, Lausanne, Neuchâtel, Sion,
Zürich, Basel, Bern, Lugano, St Gallen, Aarau) were screened for mutations
in the entire coding regions of BRCA1 and BRCA2 by PCR-
DHPLC or recently by PCR-HRM analyses. Abnormal profiles were
characterized by DNA sequencing. Large BRCA1 and BRCA2 rearrangements
were analysed by MLPA.
In 10 years, patients from 900 different families were screened for
BRCA1 and BRCA2 genes. We found 175 mutation carriers (109
BRCA1; 66 BRCA2). Only 6 of these mutations were large rearrangements
(4 BRCA1; 2 BRCA2). In the same time, 112 unknown variants
(41 BRCA1; 71 BRCA2), and a large number of BRCA1 and BRCA2
polymorphisms were also identified. Some of these mutations, unknown
variants and polymorphisms were not previously reported. On
230 relatives screened for the mutation found in the family, 106 were
carriers.
The frequency of BRCA1 and BRCA2 mutations (near 20%) in breast
and/or ovarian cancer families studied here is in the range observed in
Caucasian families. No mutation seems to prevail in the Swiss population.
P06.111
mutation screening of BRcA1 exons 2, 11 and 20 in Bulgarian
breast cancer patients
A. V. Mitkova 1 , R. Dodova 2 , M. Caulevska 2 , A. Vlahova 3 , T. Dikov 3 , T. Sedloev 4 ,
A. Jonkov 4 , I. Kremensky 5 , S. Christova 3 , V. Mitev 1 , R. Kaneva 1 ;
1 Molecular Medicine Center and Department of Chemistry and Biochemistry,
Medical University, Sofia, Bulgaria, 2 Molecular Medicine Center, Medical University,
Sofia, Bulgaria, 3 Department of Pathology, UMHAT “Aleksandrowska”,
Medical University, Sofia, Bulgaria, 4 Department of Surgery, UMHAT “Aleksandrowska”,
Medical University, Sofia, Bulgaria, 5 University Hospital of OBGYN,
Medical University, Sofia, Bulgaria.
Background: Studies on different populations worldwide demonstrate
that germ line mutations in BRCA1 and BRCA2 cancer susceptible
genes account for the majority of hereditary breast and ovarian cancers.
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