2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
P04.207
mutational spectrum of missense VHL gene mutations in spain
and their genotype-phenotype correlation
J. Oriola 1 , I. Blanco 2 , I. Salinas 3 , A. Goday 4 , J. Chillaron 4 , C. Villanova 5 , J.
Rosell 6 , S. Pedrinaci 7 ;
1 Hospital Clinic, Barcelona, Spain, 2 Institut Català d’Oncologia, Barcelona,
Spain, 3 Hospital Universitari Trias i Pujol, Barcelona, Spain, 4 Hospital del Mar,
Barcelona, Spain, 5 Hospital Princeps d’Espanya, Barcelona, Spain, 6 Hospital
Son Dureta, Palma de Mallorca, Spain, 7 Hospital Virgen de las Nieves, Granada,
Spain.
Von Hippel-Lindau (VHL) disease (MM#193300) is an inherited neoplastic
disorder characterized by a predisposition to develop mainly
retinal angiomas (RA), central nervous system hemangioblastomas
(HB), clear cell renal carcinomas (CCRC) and pheochromocytomas
(PHEO) .
It’s well known that patients that present microdeletions/insertions,
nonsense and deletion mutations usually do not develop PHEO (type
1) but do develop RA, HB and CCRC .
In patients with missense mutations, PHEO can be present (type 2)
even as the only feature, or not present . One way to improve our
knowledge about the correlation between missense mutations and
the phenotype associated is the finding of more and new mutations
in families .
We have studied 17 different families with missense mutations (12 different
mutations) and their correlation with phenotype . Eight of these
mutations fit well with the phenotype previously described: PHEO was
present in patients with G114S, R161Q, R167Q (5 families), R167W,
Y175C mutations, and PHEO was not present in patients with N78S (2
families), L128R and L178P mutations . Three mutations showed discrepancies
with the phenotype previously described according to the
presence or absence of PHEO (T157I, Q164R and L184P) . We also
describe the mutation X214R not reported previously, which was present
in a patient with bilateral PHEO . This mutation probably extends
protein by an additional 14 aminoacids .
These data support previous associations in eight mutations, add details
about genotype-phenotype correlation in three mutations and give
information about the phenotype associated to X214R mutation .
Databases searched:
The UMD-VHL Locus Specific Database: http://www.umd.be:2020/
The HGMD professional release 7 .4: http://www .hgmd .cf .ac .uk/ac/index
.php
P05. Molecular and biochemical basis of
disease
P05.001
ABcB4 gene mutations and differential involvement in liver
diseases
D. Degiorgio 1 , C. Colombo 1 , B. Acaia 1 , P. Battezzati 2 , M. Seia 1 , L. Costantino 1 ,
V. Paracchini 1 , A. Crosignani 2 , S. Nozza 1 , M. Antelmi 2 , S. Saino 1 , L. Porcaro 1 , V.
Motta 1 , C. Melles 1 , D. A. Coviello 1 ;
1 Fondazione IRCCS, Ospedale Maggiore Policlinico, Mangiagalli e Regina
Elena, Milan, Italy, 2 University of Milan, S. Paolo School of Medicine, Milan,
Italy, Milan, Italy.
ABCB4 gene mutations are responsible for type 3 Progressive Familial
Intrahepatic Cholestasis in children (PFIC3), while a possible role in
idiopathic cholangiopathies in adults has not been explored . We know
that absence or deficiency of the floppase activity necessary for biliary
excretion of phosphatidylcholine, leading to lack of phospholipid protection
in the bile against the detergent action of bile acids and damage
of the biliary epithelium . Our aim was to unveil the role of ABCB4 gene
in clinically relevant hepatobiliary diseases in children and adults .
We collected DNA samples from 168 patients (80 children with PFIC3
phenotype, 41 women with Intrahepatic Cholestasis of Pregnancy
(ICP), 16 adults with idiopathic cholestasis, 27 adults with primary
sclerosing cholangitis (PSC), 4 patients with juvenile cholelithiasis),
150 healthy subjects including 50 two-parous women without ICP .
Molecular analysis of ABCB4 gene has been so far completed in 110
patients and 100 healthy subjects .
We observed 52 ABCB4 mutations in 32 patients: 37 were found in
19 PFIC3 children, 5 in 5 ICP women, 7 in 5 patients with PSC, 2 in
2 adults with idiopathic cholestasis and 1 in one patient with juvenile
cholelithiasis . Eleven mutations (9 in PFIC3) cause truncated protein
while 41 mutations (12 in adult) cause single amino acid change .
The relative low percentage of patients which co-segregates with
ABCB4 mutations suggests a genetic heterogeneity for PFIC3 disease
and a possible role of ABCB4 as a modifier or gene susceptibility in
adults with chronic or transient cholangiopathies triggered by a cholestatic
injury .
P05.002
The autoimmune regulator PHD finger binds to non-methylated
histone H3K4 to activate gene expression
T. Org 1 , F. Chignola 2 , C. Hetényi 3 , M. Gaetani 2 , A. Rebane 1 , I. Liiv 1 , U. Maran 3 ,
L. Mollica 2 , M. J. Bottomley 4 , G. Musco 2 , P. Peterson 1 ;
1 Tartu University, Molecular Pathology, Tartu, Estonia, 2 Dulbecco Telethon Institute
c/o S. Raffaele Scientific Institute, Milan, Italy, 3 Tartu University, Institute of
Chemical Physics, Tartu, Estonia, 4 Istituto di Ricerche di Biologia Molecolare,
Pomezia, Italy.
Mutations in Autoimmune Regulator protein (AIRE) cause autoimmune
polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) .
AIRE is expressed in thymic medullary epithelial cells where it promotes
the expression of tissue-restricted antigens . By the combined
use of biochemical and biophysical methods we show that AIRE selectively
interacts with histone H3 through its first PHD finger (AIRE-
PHD1) . AIRE-PHD1 discriminates between different degrees of histone
H3 lysine 4 (H3K4) methylation and preferentially binds nonmethylated
H3K4 (KD ~4 uM) . Accordingly, in vivo AIRE binds and
activates promoters containing non-methylated H3K4 in HEK293 cells .
We propose that AIRE-PHD1 is a prototype of a new class of PHD fingers
that specifically recognize non-methylated H3K4, thus providing a
new link between the status of histone modifications and the regulation
of tissue-restricted antigen expression in thymus .
P05.003
The co-localization of ASC with Aβ fibrils in post-mortem brain
samples of Alzheimer’s disease patients
Z. E. Taskiran 1 , B. Balci-Peynircioglu 1 , F. Soylemezoglu 2 , E. Yilmaz 1 ;
1 Hacettepe University Faculty of Medicine Department of Medical Biology, Ankara,
Turkey, 2 Hacettepe University Faculty of Medicine Department of Pathology,
Ankara, Turkey.
Amyloid is an extracellular insoluble protein aggregate which accumulates
in several tissues in various clinical conditions . The co-localization
of ASC (Apoptosis associated Speck like protein containing a Caspase
recruitment domain), a key molecule in both apoptotic and inflammatory
processes, with AA type amyloid fibrils has previously been demonstrated
by our group . ASC is known to form cytosolic aggregates
called specks . The aim of this study was to determine whether the
distribution of ASC is altered around Aβ deposits and senile plaques in
post-mortem brain samples of Alzheimer’s disease patients . Immunohistochemical
staining of paraffin-embedded tissues from post-mortem
brain samples of 12 Alzheimer’s disease patients revealed co-localization
of ASC protein with senile plaques . This co-localization was
confirmed by ASC-Aβ co-staining by using immunofluorescence staining
technique . To investigate whether ASC expression was correlated
with amyloid deposition, sequential sections from AD patients were
analyzed after congo red staining . There was a strong correlation between
ASC expression and the presence of amyloid deposits . We further
investigate the interaction between ASC and Aβ in ASC-YFP and
APP (Amyloid Precursor Protein) co-transfected COS-7 cells which
also demonstrated that specks are located near the intracellular Aβ
deposits . We hypothesize that expression of ASC may be important in
the pathogenesis of Aβ amyloid formation and in senile plaque develoment
in predisposed tissues .) Further functional studies are required to
explore the link between ASC and Aβ amyloid formation.
P05.004
A new candidate haplotype in the ps2 gene associated with lateonset
familial alzheimer disease?
J. I. Lao 1 , C. Montoriol 1 , I. Morer 1 , E. Fernández 1 , D. Poyatos 1 , K. Beyer 2 ;
1 Unit of Molecular Genetics - Medical Lab. Dr. Echevarne, Barcelona, Spain,
2 Pathology Department, Hospital Germans Trias i Pujol, Badalona, Spain.
Mutations within the APP, presenilin 1 (PS1) or presenilin 2 (PS2)
genes are found in familial Alzheimer disease (AD) . Whereas mutations
within PS1 cause AD of early or very early onset, APP as well as