2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
test . VDR genotype frequencies were in Hardy-Weinberg equilibrium .
We also carried out haplotype analysis as the polymorphisms are inherited
together. In patients, six different haplotypes were defined, with
over-representation of BAt (40 .7%) . On the other hand, baT haplotype
was the most frequent in controls . BaT haplotype was four times and
bAt haplotype was two times more frequent than in controls . This study
also provides evidence that there is a statistically significant association
of the bT VDR haplotype and formation of CaOx kidney stones .
P06.321
changes in ca homeostasis lead to electrical and structural
remodeling of the heart in the ‚human PLN‘ mouse mode
D. A. Arvanitis1 , M. Dong2 , W. Zhao2 , V. Papalouka1 , E. G. Kranias1 , H. S.
Wang2 , D. Sanoudou1 ;
1Biomedical Research Foundation of the Academy of Athens, Athens, Greece,
2University of Cincinnati, Cincinnati, OH, United States.
Phospholamban (PLN), the reversible inhibitor of SERCA2, is a key
regulator of calcium homeostasis and cardiac function, and it has been
directly implicated in the development of dilated cardiomyopathy . Its
amino acid sequence is highly conserved across species except for
humans, where Asn is replaced by Lys at amino acid position 27 . To
evaluate the significance of this single nucleotide difference we induced
cardiac-specific insertion of the human-PLN in the null background
. The “humanized” PLN expressing transgenic (TG) mouse
hearts presented increased inhibition of SERCA2, abnormal calcium
handling, fibrosis, and hypertrophy. Using whole genome microarrays
(Codelink), we identified significant changes in ion transport, muscle
contraction, cell cycle and proteolysis, as well as numerous transcription
related genes . The observed changes in key sodium, potassium
and calcium plasma membrane pumps were confirmed at the protein
level and suggested an ongoing electrical remodeling process . In support
to these findings, ex vivo Langendorff perfusion of intact hearts
revealed decreased rates of contraction and relaxation in TG mice .
Furthermore, patch clamp analysis of isolated cardiac myocytes unveiled
significantly prolonged cardiac myocyte action potential, decreased
transient outward current (Ito) and increased sodium/calcium
exchanger activity. Significant changes were also detected in key cytoskeletal
and contractile proteins . In conclusion, “human-PLN” directly
affects calcium cycling and contractility, which in turn triggers electrical
and structural remodeling . These compensatory mechanisms ultimately
enable long term survival of the TG mice .
P06.322
the Human and canine Dopamine D4 Receptor Genes
E. Szantai 1 , K. Héjjas 1 , J. Vas 2 , A. Miklósi 2 , J. Topál 2 , Z. Rónai 1 , M. Sasvári-
Székely 1 , M. Sasvári-Székely 1 ;
1 Institute of Medical, Chemical, Molecular Biology and Pathobiology, Semmelweis
University, Budapest, Hungary, 2 Department of Ethology, Eotvos Lorand
University, Budapest, Hungary.
The human dopamine D4 receptor (DRD4) is a candidate gene of great
interest in molecular studies of human personality and psychiatric disorders
. This gene is unique in having an exceptionally high amount of
polymorphic sites both in the coding and in the promoter region . One
of the most thoroughly investigated polymorphisms is the 48 base pair
variable number of tandem repeats in exon III that has been carefully
studied as a possible genetic risk factor for several psychological traits
and psychiatric disorders, such as novelty seeking, drug abuse and
attention deficit hyperactivity disorder.
Mice or rat possess no analogous repeat sequences, whereas similar
tandem repeat polymorphism of the DRD4 gene was identified in dogs
and chimpanzees . Therefore, genotyping method was developed for
exon III length polymorphism of DRD4 gene in dogs; genotype and allele
frequency values were measured in several dog breeds, in wolves
and in human DNA samples .
Moreover two other VNTRs were identified and analyzed in dogs in
exon I and intron II of the DRD4 gene and were found to be polymorphic
.
Our results show that DRD4 gene is also variable in dogs, which means
that these animals have the potential to become a natural model for
testing relationships between this candidate gene polymorphism and
psychiatric disorders (such as hyperactivity) .
P06.323
Expression profiles of non-syndromic thoracic aortic aneurysms
C. Patuzzo1 , A. Pasquali1 , M. Iafrancesco2 , G. Faggian2 , I. Dal Pra3 , A. Chiarini3
, U. Armato3 , A. Mazzucco2 , P. F. Pignatti1 , E. Trabetti1 ;
1 2 Department of Mother and Child and Biology-Genetics, Verona, Italy, Division
of Cardiac Surgery, Dpt of Biomedical and Surgical Sciences, Verona, Italy,
3Histology and Embryology Unit, Dpt of Biomedical and Surgical Sciences,
Verona, Italy.
Thoracic aortic aneurysms occur when the arterial wall is unable to
resist the dilating force of arterial pressure . Aortic aneurysms tend to
expand without symptoms until aortic rupture or dissection take place .
The aim of the study has been to define the molecular circumstances
in which non-syndromic aneurysm of thoracic ascending aorta can develop
.
Fragments of human ascending thoracic aortas with (35, cases) and
without (22, controls) aneurysms have been isolated during surgical intervention
(aortic/cardiac transplantation or aortic valve replacement) .
The three layers of each isolated aortas have been dissected . We now
report on media layer results .
Gene transcription and proteomic profiles of the aneurysmal compared
to non aneurysmal aortic media layer have been studied . Our preliminary
oligonucleotide microarray (22000 genes) results evidenced
down regulation of genes such as Decorin (DCN), Thrombospondin 1
(THBS1), Reticulocalbin 2 (RCN2), Reticulon 1 and 4 (RTN1 and 4) .
Paucity of these transcripts delineate a structural lack of resistance to
mechanical stress and an increase of angiogenesis possibly as an attempt
to remodeling the vessel . Proteomic analysis indicated an hyper
expression of Testican 2 (SPOCK2) and Jagged 1 (JAG1), confirmed
by Real Time PCR analysis: mRNAs for these genes are upregulated .
The implication of angiogenesis in the aneurysmal aorta is consistent
with upregulated Eph transcripts found in microarray analysis . Preliminary
results from microRNA microarray (794 miRNA) analysis indicate
differential expression between cases and controls of miRNA 15, 16,
21, 128, 487, and 133, and this is consistent with down and up regulated
genes found .
P06.324
Determination of a novel OA1 gene deletion identified by MLPA
in a spanish family.
M. Martínez-García1,2 , C. Villaverde1,2 , M. López-Martínez1,2 , R. Cardero1,2 , D.
Cantalapiedra1,2 , E. Vallespín1,2 , R. Riveiro-Álvarez1,2 , M. Rodríguez de Alba1,2 ,
M. Trujillo-Tiebas1,2 , C. Ayuso1,2 ;
1 2 Fundación Jiménez Díaz, Madrid, Spain, Centro de Investigación Biomédica
en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain.
Nistagmus is the common symptom of a range of diseases involving
the macula, including X-linked disorders like ocular albinism type 1 .
Prevalence of OA type 1 is estimated around 1 in 50,000 live births in
Caucasian populations . The OA1 gene, which has been assigned to
the Xp22 .3 region and spans approximately 40 Kbp of genomic DNA
containing nine exons, encodes a melanosomal membrane glycoprotein
G consisting of 404 residues belonging to the protein-coupled receptor
family .
A purified DNA sample of a female carrier in a Spanish family suffering
from ocular albinism was subject to the p054 probe mix of MLPA,
showing a decreased peak corresponding to exon 2 of the OA1 gene .
In order to determine whether the OA1 gene was altered, we analysed
a DNA sample from an affected male (proband’s father), and after
MLPA, no peak was observed . Therefore, we focused our sequencing
analysis on exon 2 because it appears to be particularly prone to deletions.
Here, we report a mutation (g.5815delA) identified in 2 affected
males and 4 female carriers of this particular family . This mutation
which results in a truncated protein 35 codons downstream, generates
a new restriction target site for XcmI, that we further confirmed by digestion
of DNA from the 6 affected patients . Indirect approach analysis
by using OA-CA, a STR located in intron 1, showed co-segregation
with the disease in the family .
In conclusion, the prior screening by MLPA is a suitable molecular
strategy for diagnosis of patients suffering from X-linked ocular albinism
.