2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
P05.156
Identification of two novel mutations in LRRK among iranian
Parkinson’s Disease patients
Z. Fazlali 1,2 , S. Shojaee 3 , N. Farboodi 1 , F. Ghazavi 1 , G. Shahidi 4 , F. Sina 4 , B.
Zamani 4 , H. Sadeghi 5 , K. Parsa 5 , E. Elahi 1,6 ;
1 School of Biology, College of Science, University of Tehran, Tehran, Islamic
Republic of Iran, 2 Iranian National Elite Foundation, Tehran, Islamic Republic of
Iran, 3 Department of Biotechnology, College of Science, University of Tehran,,
Tehran, Islamic Republic of Iran, 4 Iran University of Medical Sciences, Hazrat
Rasool Hospital, Tehran, Islamic Republic of Iran, 5 Neurosurgery, Shahid
Beheshti University of Medical Sciences, Tehran, Islamic Republic of Iran,
6 Center of Excellence in Biomathematics, School of Mathematics, Statistics and
Computer Science, College of Science, University of Tehran, Tehran, Islamic
Republic of Iran.
Parkinson’s Disease (PD) is one of the most common progressive
neurodegenerative disorders . It is characterized by selective loss of nigrostriatal
dopaminergic neurons . Five genes associated with PD have
been identified by linkage analysis of affected families: α-synuclein,
parkin, DJ-1, PINK-1 and LRRK2 . Mutations in the Leucine-rich repeat
kinase 2 (LRKK2) gene have been most often observed in autosomal
dominantly inherited PD, a form of the disease which has pathological
features most closely resembling those seen in idiopathic forms
of PD . Among the approximately 80 exonic variations so far observed
in LRRK2, less than 10 are definitively thought to cause PD. In this
study, we sequenced exons 36 and 37 of LRRK2 in 60 PD Iranian PD
patients . Two novel heterozygous variations, c .G5174A in exon 36 and
c .C5467A in exon 37 were observed . Each variation was observed in
only one patient. The first causes substitution of arginine by glutamine
at position 1725 (R1725Q), and the second causes substitution of glutamine
by lysine at position 1823 (Q1823K) .Both affected residues are
located in the COR (carboxy-terminal of Ras) domain, where at least
one pathogenic mutation has been previously identified. To assess
the presence of c .G5174A and c .C5467A in other PD patients and in
controls, an ARMS-PCR assay was set up for each of the variations .
Neither variation was observed among 230 healthy controls and 115
additional unrelated PD patients . Although these observations suggest
that both variations may be disease associated mutations, this conclusion
is presently not conclusive .
P05.157
A Yeast Two hybrid screen for LRRK2
S. Jain 1,2 , E. Greggio 2 , A. Kaganovich 2 , P. Heutink 1 , M. Cookson 2 ;
1 CNCR, Amsterdam, The Netherlands, 2 NIA, Bethesda, MD, United States.
Mutations in Lrrk2 cause autosomal dominant Parkinson’s Disease .
LRRK2 (DARDARIN) belongs to a newly identified family of proteins
referred to as ROCO proteins that contain two conserved domains (i)
a ROC (Ras in complex proteins) domain that and ii) a COR domain
(C-terminal of ROC) . In addition LRRK2 also contains a WD40 and
a leucine rich repeat domain, as well as a predicted tyrosine kinase
catalytic domain . A yeast two hybrid was performed to help elucidate
the function of LRRK2 .
LRRK2 was found to interact with fasciculation and elongation factor
zeta 2 (FEZ2), a mammalian orthologue of the Caenorhabditis elegans
UNC-76 protein, which is involved in the axonal outgrowth and synaptic
organization . FEZ2 is ubiquitously expressed in mammalian tissues
with the majority of information about its function being inferred from
studies of its homolog, FEZ1 . FEZ1 appears to be involved in neuritogenesis
upon phosphorylation by PKCζ. Knockout of UNC-76 from
C-elegans leads to locomotion and axonal transport defects . Given the
role of FEZ1 in axonal outgrowth and normal synaptic function, FEZ2
and LRRK2 may co-operate in maintaining SN neuritic length and
branching, and makes FEZ2 a good functional interactor for LRRK2 . In
support of this hypothesis, recent evidence has suggested that LRRK2
plays a role in maintaining neuronal morphology in vitro and in vivo .
P05.158
Effect of overexpression of PKD2 in a murine model
E. Ribe1 , S. Burtey1 , M. Riera1 , R. Rance1 , E. Passage1 , P. Pennekamp2 , B.
Dworniczak2 , M. Fontés1 ;
1 2 INSERM U491, Marseille, France, Institute for Human Genetics, Muenster,
Germany.
Polycystin-2 (PC-2), a cation channel of the Trp family, is involved in
autosomal dominant polycystic kidney disease (ADPKD) type 2 (AD-
PKD2) . This protein has recently been localized to the primary cilium
where its channel function seems to be involved in a mechanosensory
phenomenon . However, its biological function is not totally understood,
especially in tubule formation . We describe a mouse model for human
PC-2 overexpression, obtained by inserting a human BAC containing
the PKD2 gene . Three lines were generated, expressing different levels
of PKD2 . One line, PKD2-Y, has been explored in more details and we
will present physiological and molecular exploration of this transgenic
animals . Our data demonstrate that transgenic animals older than 12
months present tubulopathy with proteinuria and failure to concentrate
urine . The kidney cortex has been found disorganized . Moreover, we
observe that extracellular matrix protein expression is downregulated
in these animals . Overexpression of human PKD2 leads to anomalies
in tubular function, probably due to abnormalities in tubule organogenesis.
Surprisingly, PKD2-Y FISH analysis showed that a significant
number of metaphases presented with more than a single Y chromosome
. Transgenic nucleus size is larger compared to non-transgenic
cells suggesting problems during cell division . Likewise we show that
fibroblasts from transgenic mouse present with mitotic instability. It remains
to be determined what is the relationship between PC-2 and
cell division .
P05.159
Gene expression in 2-3 somite stage Wt and Pkd2 mutant
mouse embryos
P. Pennekamp, M. Dahmer, G. Randau, N. Koo, B. Dworniczak;
University Clinics Muenster, Muenster, Germany.
The development of an invariant left-right (LR) asymmetry of the visceral
organs is a fundamental feature of vertebrate embryogenesis .
Failure to establish the normal organ position (situs solitus) may result
in a mirror-image reversal (situs inversus), in left or right isomerism
or in heterotaxia (situs ambiguous) . While the complete situs inversus
does not have adverse impact on the organisms, heterotaxia frequently
is accompanied by fatal malformations and complex cardiac
and cardiovascular defects . Increasing evidence based on research
on genetically modified animals including our Pkd2 knockout mouse
suggest, that the disturbance of proper LR axis development and thus
misalignment of the developing heart tube is one of the major causes
for the development of congenital heart disease (CHD) resulting in
early prenatal death in most cases and it is very likely that the same
mechanisms are responsible in large part for early abortions in the first
trimester of pregnancy in humans .
To identify and to characterize novel genes and mechanisms which
influence LR axis development in vertebrates and thus might be involved
in the development of congenital cardiac defects we performed
a gene expression analysis of right and left body halves of 2-3 somite
stage male WT and Pkd2 mutant mouse embryos using Affymetrix
Gene Chips. We identified and validated by in situ hybridization (ISH)
analyses several genes which are either already known or highly suggestive
to influence LR axis development. Data obtained during this
analysis will be presented .
P05.160
Genetic mechanisms involved in the pathogenesis of premature
ovarian failure: study of FMR , cryptic anomalies (especially
small deletions) in the Xq27-Xqter region and other causative
genes, in 122 women from the Basque country.
M. I. Tejada 1 , E. Beristain 1 , C. Martinez-Bouzas 1 , N. Puente 1 , N. Viguera 1 , M.
Artigas 2 , M. A. Ramos-Arroyo 2 , B. Prieto 1 , S. González 3 , J. Peña 4 , R. Matorras
1,3 ;
1 Hospital de Cruces, Barakaldo-Bizkaia, Spain, 2 Hospital Virgen del Camino,
Pamplona, Spain, 3 IVI-Bilbao, Leioa-Bizkaia, Spain, 4 Instituto Ginecológico
Elcano, Bilbao, Spain.
Premature Ovarian Failure (POF) is characterized by secondary
amenorrhea, elevated level gonadotropins and sex steroid deficiency
in women less than 40 years old . It is well known that some of the Premutation
(PM) carrier women of Fragile X Syndrome (FXS) develop
POF. More recently, it has been identified a common region responsible
for ovarian development -Xq27-Xqter-, where the FMR1 gene
lies and interestingly, so lie other X-linked genes for MR . Furthermore,
there are other genes in the pathogenesis of POF, the results being
that it is heritable in up to 30% .of cases .
We studied all of these genetic mechanisms in peripheral blood sam-