2008 Barcelona - European Society of Human Genetics

Cancer genetics
The system has shown accuracy, precision and dynamic range in the
thirty-three nanoliter reaction volumes identical to the same reactions
performed in 100-fold larger volumes typical for rt-PCR in 384-well microplates
. A 64-fold increase in analytical throughput relative to 384well
microplates simplified quantification of message RNA, resulting
in unprecedented throughput and sensitivity suitable for detection of
low abundance nucleic acids as well as low consumable costs . We
show the utility of this system for studying two different areas of cancer
biology . First, the expression of over 500 kinase genes was screened
in three types of tumor tissues and the biological significance of regulated
genes in regulating the cell cycle was confirmed. Second, we
studied its utility for screening for DNA methylation as a biomarker for
tumor detection .
P04.193
setting up of a questionnaire by the genetic counselor to
optimize the collection of data during the first consultation of
cancer genetics
A. Combes1 , K. Baudry-Samb1 , P. Pujol1 , J. Duffour2 , I. Coupier1,2 ;
1 2 CHU Arnaud de Villeneuve, Montpellier, France, CRLC Val d’Aurelle, Montpellier,
France.
Persons presenting a hereditary predisposition for cancer are addressed
to a consultation of cancer genetics because of their personal
and family history of cancers . During consultation a family pedigree is
drawn, genetic counselor collects information to evaluate hereditary
predisposition. All this information is difficult to obtain if the patients
are not informed of the questions which will be asked to them during
consultation .
The aim of this study is to optimize the collection of information using a
questionnaire targeting essential data during this first consultation.
This questionnaire was addressed to all patients making an appointment
for a first consultation. It gathers personal and medical information,
in both parental branches over three generations . Questionnaires
were assessed according to two criteria : their return and filling up
rates .
The return rate is 82 % (110/134). The mean filling up rate is 74 % and
for more than 86 % of questionnaires, the amount of information is very
satisfactory (questionnaires supplemented in 60, 80 and 100 %) .
The questionnaire has a double interest, for the patients and for the
medical team . The patients collected a lot of information on their family
before their consultation . For the medical team, data necessary for the
realization of the family pedigree are gathered in a more precise and
quicker manner .
Considering the good return and filling up rates of this questionnaire,
we decided to insert it into the daily practice of our consultations .
P04.194
Analysis of the molecular-genetic alterations in the genes VHL,
RAssF1, and FHit in clear cell renal carcinomas
D. S. Mikhaylenko 1,2 , A. M. Popov 3 , R. V. Kurynin 4 , D. V. Zaletayev 1,2 ;
1 Research Centre for Medical Genetics RAMS, Moscow, Russian Federation,
2 Institute of Molecular Medicine of Sechenov Moscow Medical Academy,
Moscow, Russian Federation, 3 Medical Radiological Research Center RAMS,
Obninsk, Russian Federation, 4 Clinic of Urology of Sechenov Moscow Medical
Academy, Moscow, Russian Federation.
Clear cell renal carcinoma accounts approximately 75% patients with
kidney cancer and characterized by alterations of the genes VHL,
RASSF1, FHIT . We have conducted the molecular-genetic study of
mutations, loss of heterozygosity, methylation of the VHL gene as well
as allelic deletions of the genes RASSF1 and FHIT in 123 clear cell renal
carcinomas for the development of renal cancer prognostic criteria .
VHL mutations were detected by SSCP and subsequent sequencing;
methylation was tested by methylsensitive polymerase chain reaction .
Loss of heterozygosity was analyzed using STR-markers D3S1317
and D3S1038 (VHL), D3S1568 and D3S966 (RASSF1), D3S1234
and D3S1300 (FHIT) . VHL somatic mutations were observed in 31 .7%
samples, 84.6% of them were identified for the first time. We have detected
VHL allelic deletions in 27 .9% informative cases, and aberrant
methylation - in 14 .6% heterogeneous tumor samples . VHL inactivating
events were presented in 53 .8% patients with stage I, and could
be responding for early gene inactivation . RASSF1 and FHIT allelic
deletions were observed in 27 .5% and 35 .6% informative cases, correspondingly
. Loss of heterozygosity of two or three analyzed genes in
primary tumor was associated with metastases in the regional lymph
nodes and/or distant metastases (P = 0 .036, OR = 1 .49, 95% CI: 1 .01-
2 .33) . Results of this investigation could be used for selection of prognostic
molecular markers of clear cell renal cancer .
P04.195
Under-representation of the REt sequence variants G691s and
s904s in patients with a common c618R REt proto-oncogene
mutation
V. Neocleous1 , V. Anastasiadou2,1 , M. Pantzaris1 , N. Skordis2 , L. A. Phylactou1 ;
1 2 The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus, Makarios III
Hospital, Nicosia, Cyprus.
Medullary thyroid carcinoma (MTC) occurs in a sporadic or as an autosomal
dominant heretidary form . Inherited forms of MTC are related
to mutations in the RET proto-oncogene. Identification of polymorphic
variants that increase susceptibility and variations in pathological phenotypes
is a frequent question that is addressed in medical genetics . In
various studies which resulted to conflicting results a number of polymorphisms
within the RET proto-oncogene were proposed to act as
low penetrance predisposing alleles . In the present study, in order to
test for the contributory role of the polymorphisms G691S and S904S,
in the development of MEN2A, we looked for an association of these
RET haplotypes in hereditary MEN2A cases and in controls from individuals
of Greek Cypriot origin .
Screening for the polymorphic variants G691S/S904S was performed
in 226 Greek Cypriots who served as controls and in 6 unrelated Greek
Cypriot patients diagnosed with MEN2A with the C618R mutation . In
controls, the allelic frequencies of G691S/S904S polymorphisms were
found in the heterozygous state in 102/226 (45 %) individuals, and in
the homozygous state in 11/226 (~5 %) . In all cases, these polymorphisms
were in co-segregation . This allelic frequency for the polymorphisms
G691S/S904S of the RET gene in the Greek Cypriot population
is the highest reported so far among normal individuals . Moreover,
only 1/6 (16 .66 %) patients with MEN2A had the G691S/S904S
polymorphisms in the heterozygous state . This under-representation
of the G691S/S904S polymorphic variants in MEN2A patients, might
suggest a possible synergistic and protective effect exercised by these
polymorphisms .
P04.196
Variants in the retinoblastoma gene: neutral polymorphism or
pathogenic change?
C. J. Dommering 1 , A. H. van der Hout 2 , S. M. Imhof 3 , A. C. Moll 3 , M. Burton 2 , Y.
J. Vos 2 , H. J. Meijers-Heijboer 1 ;
1 Department of clinical genetics, VU University Medical Center, Amsterdam,
The Netherlands, 2 Department of genetics, University Medical Centre Groningen,
Groningen, The Netherlands, 3 Department of ophthalmology, VU University
Medical Center, Amsterdam, The Netherlands.
Retinoblastoma is a malignant neoplasm of the developing retina, occurring
mostly in early childhood . The birth prevalence is between 1 in
15 .000 and 1 in 20 .000 . Hereditary (40% of cases) as well as non-hereditary
(60% of cases) retinoblastoma (RB) result from inactivation of
both alleles of the tumor-supressor gene RB1, located on chromosome
13q14 . In hereditary RB, the mutated gene is transmitted in an autosomal
dominant way, usually with almost complete penetrance . We have
performed DNA-mutation scanning (sequencing of exon 1, 15 and the
RB1-promoter, DGGE analysis of the other exons and MLPA analysis
for large deletions and duplications) in 411 RB-patients and found
causative RB1-mutations in 173/197 (88%) bilateral/familial patients
and 18/214 (8 .4%) in unilateral non-familial cases . Most mutations
are nonsense changes or small insertions or deletions causing frameshifts
. However, for some changes it is not immediately clear if they are
pathogenic mutations or just neutral variants . These include missense
changes, synonymous changes, small in-frame deletions and intronic
variants at other sites than the invariable splice donor and acceptor
sequences . These variants cause serious problems in genetic counselling
of RB patients and their family . We will discuss several variants
with unknown significance in the RB1-gene, 15 missense changes, 11
intronic variants, 2 synonymous changes en 1 in frame deletion, and
illustrate ways to substantiate their pathogenicity .