2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
and Western blot, the secretion, endoproteolytic processing and extracellular
aggregates of wild-type myocilin and 5 glaucoma-associated
myocilin mutants (E323K, R346T, Q368X, P370L and D380A)
transiently co-expressed in a cell line in culture . Our results show that
coexpression affects secretion and proteolytic processing of wild type
and mutant myocilins . These phenomena could play a role in the development
of glaucoma .
P05.058
screening for glucocorticoid-remediable aldosteronism among
hypertensive patients in Bulgaria
J. A. Matrozova 1 , R. Saraeva 2 , R. Bogeska 2 , R. Kaneva 2 , I. Kremensky 2 , S.
Zacharieva 1 ;
1 University Hospital of Endocrinology “Akad. Ivan Pentchev”, Sofia, Bulgaria,
2 Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria.
Background. Primary aldosteronism (PA) is currently considered the
most frequent form of endocrine hypertension . Glucocorticoid-remediable
aldosteronism (GRA) is a genetic variety of PA, affecting about
1% of patients, which is inherited in an autosomal dominant pattern .
GRA is caused by a chimaeric gene with aldosterone synthase activity
originating from an unequal crossing-over between the CYP11B1
(11 beta-hydroxylase) and CYP11B2 (aldosterone synthase) genes .
Hypertension in GRA can be severe leading to cerebrovascular complications
at a young age and female carriers of the mutation have
a higher incidence of preeclampsia during pregnancy . On the other
hand GRA can be successfully treated by glucocorticoids, which justifies
its screening and early diagnosis. Objective. The aim of this study
was to assess the prevalence of GRA among patients with confirmed
PA . methods. The study population consisted of 170 hypertensive patients,
referred to a specialized Endocrinology department . In order to
identify patients with PA we used the aldosterone to renin ratio and the
Captopril test. The diagnosis of PA was confirmed in 11 subjects who
were investigated for GRA using the long PCR technique . Results.
None of our patients was positive for the CYP11B1/CYP11B2 chimaeric
gene. coclusions. Our study demonstrated that GRA can be successfully
excluded in patients with PA, using the long PCR technique .
Further studies in larger groups of patients are needed to evaluate the
prevalence of GRA among patients with PA, which is probably lower
than previously reported
P05.059
the crv mouse model reveals a new role of the metabotropic
glutamate receptor type 1 (Grm ) in the kidney glomerulus
A. Puliti 1,2 , V. Conti 1,3 , G. Caridi 4 , A. Corbelli 5 , L. Musante 3,4 , F. Piccardi 6 , J. L.
Guenet 7 , G. Candiano 4 , R. Gusmano 3 , M. P. Rastaldi 5 , R. Ravazzolo 1,2 ;
1 Molecular Genetics and Cytogenetics Unit, G. Gaslini Institute, Genova, Italy,
2 Dept. of Pediatric Sciences “G. De Toni”, University of Genova, Genova, Italy,
3 RenalChild Foundation, G. Gaslini Institute, Genova, Italy, 4 Laboratory on
Pathophysiology of Uremia, Gaslini Institute, Genova, Italy, 5 Renal Immunopathology
Laboratory, D’Amico Renal Research Foundation, Milano, Italy, 6 Animal
Models Facility, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy,
7 Pasteur Institute, Paris, France.
We recently described the crv4 mouse mutant, where a spontaneous
mutation causes the lack of the metabotropic glutamate receptor
type 1 (Grm1) . Homozygous crv4 mice exhibit a complex phenotype,
mainly characterized by ataxia and by morphological and functional
renal anomalies .
By PCR screening of a cDNA library of human tissues, we found Grm1
expressed in the kidney . Expression of Grm1 was also evidenced by
amplifying and sequencing cDNA obtained from renal tissues of wild
type mice. The expression of the receptor was confirmed in wild type
renal tissues by western-blot and immunofluorescence analyses, using
specific antibodies.
Electron microscopy analyses of the crv4 kidneys, compared to the
wild type, evidenced major glomerular alterations of the glomerular
basement membrane and the podocytes, and immunofluorescence
analyses of specific podocyte proteins, such as nephrin, synaptopodin,
and ZO1, showed a reduced expression in the mutated mice .
Urine analyses by ELISA showed a statistically significant albuminuria
in crv4 homozygous relative to wild type mice .
These evidences support a recent hypothesis according to which
podocytes communicate by neuron-like mechanisms . The podocyte,
similarly to the neuronal cell, has vesicular structures for the exocy-
tosis/endocytosis and release of glutamate . In this view, mutations of
molecules involved in such mechanisms may be added to other known
genetic causes of glomerulopathies .
P05.060
Identification, characterization and regulatory role of a new
tFii-i family member, GtF2iRD2, located at the Williams-Beuren
syndrome locus
A. Antonell 1 , M. I. Tussie-Luna 2 , A. L. Roy 2 , L. A. Pérez-Jurado 1,3 ;
1 Unitat de Genètica, Universitat Pompeu Fabra, U-735 CIBERER, Barcelona,
Spain, 2 Dept. of Pathology, Tufts University School of Medicine, Boston, MA,
United States, 3 Programa de Medicina Molecular i Genètica, Hospital Vall
d’Hebron, Barcelona, Spain.
GTF2I, GTF2IRD1 and GTF2IRD2 are three related genes located in
the 7q11 .23 Williams-Beuren Syndrome (WBS) locus that encode different
members of the TFII-I family of transcription factors, characterized
by the presence of several HLH-like domains known as I-repeats .
The functions of GTF2I and GTF2IRD1, hemizygously deleted in all
typical WBS patients, have been studied in depth . However, little is
known about GTF2IRD2, a multicopy gene that is variably deleted in
WBS patients, and thus a candidate to influence the variable severity
of the phenotype . We have studied the function of the three expressed
GTF2IRD2 copies termed medial, telomeric and the chimeric found in
some WBS patients . In vitro transfection assays in COS7 cells revealed
that all three GTF2IRD2 proteins formed heterodimers with GTF2I, but
only the GTF2IRD2-tel copy could interact with GTF2IRD1 . The cellular
localization pattern was different among the three proteins . GTF2IRD2tel
protein appears mainly nuclear while the GTF2IRD2-chi was found
to be mostly cytoplasmatic . The GTF2IRD2-tel and GTF2IRD2-med
proteins, but not the GTF2IRD2-chi, changed their distribution pattern
when co-transfected with GTF2I and GTF2IRD1 . In addition, the GT-
F2IRD2-tel protein was able to activate transcription of the c-fos gene
in a synergistic way with GTF2I . In conclusion, GTF2IRD2 proteins
appear to act as transcription regulators by virtue of interacting with
GTF2I and GTF2IRD1 with different functional outcomes . The variable
amount of the different TFII-I family proteins in WBS patients, depending
on deletion breakpoints, could contribute to modulate the variable
expression of target genes and thus the WBS phenotype .
P05.061
investigating Factor V (G1691A), Prothrombin (G20210A)
and methylenetetrahydrofolate reductase (c677t) gene
polymorphisms in recurrent pregnancy loss
H. Samli 1 , N. Imirzalioglu 1 , G. Koken 2 , A. Ozgoz 1 , G. Ceylaner 3 , S. Ceylaner 3 ;
1 Afyon Kocatepe University, School of Medicine, Department of Medical Genetics,
Afyonkarahisar, Turkey, 2 Afyon Kocatepe University, School of Medicine,
Department of Obstetrics and Gynecology, Afyonkarahisar, Turkey, 3 Zekai Tahir
Burak Women’s Hospital, Department of Genetics, Ankara, Turkey.
In 75% of women trying to be pregnant, early pregnancy loss occurs .
Habitual abortion is the termination of two or more consecutive pregnancies
before 20th gestational week .
Various etiologic factors are responsible for recurrent pregnancy loss .
In the performed studies these factors are reported to be, 7% chromosomal
abnormalities, 10% anatomic problems, 15% hormonal irregularities,
6% unclear reasons and 55-62% coagulation protein/platelet
problems. The importance of genetic defects causing defficiency in the
coagulation system are better understood recently . Among them the
most frequently related ones are some of the mutations take place in
the Factor V, Prothrombin and the MTHFR genes .
In our study we objected to investigate the existence of the FV Leiden,
Prothrombin and MTHFR gene mutations in 110 women with recurrent
pregnancy loss and in 30 women with healthy children and no pregnancy
loss . Mutation screening was perfomed by PCR-RFLP method
using Hind III and Hinf I restriction enzymes for the blood samples of
which DNAs were isolated .
FV Leiden, Prothrombin, MTHFR mutations were detected to be 13 .6
%, 6 .4%, 55 .5% in the case and 6 .7%, 6 .7%, 53 .3% in the control
groups, respectively. No significant differences were detected between
the case and the control group according to the mutation frequencies .
It is thought that the risk of pregnancy loss is related to the combined
augmentation of the thrombophilic mutations rather than a specific mutation
. Probably, investigating prevalence of more thrombophilic mutations
in women with habitual abortion will be more significant.