2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
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Clinical genetics and Dysmorphology<br />
Our goal was to look for other patients with duplication <strong>of</strong> GRIA3 by<br />
performing Multiplex Ligation-dependent Probe Amplification (MLPA).<br />
We selected about twenty patients with MR based either on their facial<br />
features or on their behavioral disorders.<br />
We found a duplication <strong>of</strong> GRIA3 resulting from a 2.8 Mb duplication at<br />
Xq25 in a 4-year-old boy who had a similar facial appearance. These<br />
two patients presented a common clinical phenotype: psychomotor<br />
delay, hypotonia, mild mental retardation, pervasive developmental<br />
disorder and non specific cerebral MRI abnormalities associated with<br />
characteristic facial features including malar flatness, lower palpebral<br />
eversion, thick lips and hypotonic facies. In both cases, the duplication<br />
was maternally inherited. The mothers presented an X inactivation<br />
bias and were unaffected.<br />
We suggest that the Xq25 region duplication may result in a clinically<br />
recognizable condition. In particular, facial dysmorphism could help to<br />
diagnose this microduplication in males with X-linked MR.<br />
P02.196<br />
A duplication encompassing the SMS gene involved in a Xlinked<br />
mental retardation different from snyder-Robinson<br />
syndrome<br />
A. Delahaye 1 , E. Pipiras 1 , S. Drunat 2 , C. Dupont 1,2 , A. Tabet 2 , A. Aboura 2 , J.<br />
Elion 2 , B. Benzacken 1,2 , L. Burglen 3 ;<br />
1 Histology-Embryology-Cytogenetics Department, APHP-Jean Verdier University<br />
Hospital, UFR SMBH, Paris 13 University, Bondy, France, 2 Department <strong>of</strong><br />
<strong>Genetics</strong>, APHP-Robert Debré University Hospital, and INSERM U676, Paris,<br />
France, 3 <strong>Genetics</strong> Department, AP-HP-Armand Trousseau University Hospital,<br />
Paris, France.<br />
Duplications on the X chromosome have been rarely reported in males<br />
with mental retardation and dysmorphism. In most <strong>of</strong> cases they are inherited<br />
from female carrier phenotypically normal. We describe the molecular<br />
characterization <strong>of</strong> a maternal interstitial dup(X)(p22.11p22.12)<br />
encompassing the spermine synthase (SMS) gene in two brothers with<br />
mental retardation.<br />
Clinically the two brothers demonstrated mild mental retardation, epicanthus,<br />
short up-slanting palpebral fissures, short extremities and<br />
hollow feet. The first one presented a strabism and cryptorchid testes,<br />
and the second a congenital club foot. Short hands and feet were also<br />
observed in the mentally normal mother.<br />
An Integragen BAC-array showed a gain for CTD-2033A1 clone, not<br />
confirmed by FISH analysis. Agilent 44K oligo-array confirmed the gain<br />
and precise the size (460 Kb). Quantitative real-time PCR confirmed<br />
the duplication in both brothers and showed the duplication was inherited<br />
from their mother. The genes included in the duplication were<br />
SMS and PHEX.<br />
We discuss the implication <strong>of</strong> SMS gene in the phenotype <strong>of</strong> our patients.<br />
SMS gene mutations were shown to be involved in the X-linked<br />
recessive mental retardation Snyder-Robinson syndrome (OMIM<br />
309583). This syndrome is characterized by a marfanoid habitus with<br />
long thin hands and feet. We suggest that the SMS gene could be<br />
involved in another X-linked mental retardation than Snyder-Robinson<br />
syndrome. Skeletal abnormalities in our patients (short hands and feet)<br />
are the opposite <strong>of</strong> what is described in lost <strong>of</strong> function <strong>of</strong> SMS gene.<br />
Finally, this report contributes to the clinical and genetic delineations <strong>of</strong><br />
the SMS gene defects.<br />
P02.197<br />
the role <strong>of</strong> miRNA-105 in the development <strong>of</strong> nonsyndromic<br />
mental retardation<br />
I. Minniakhmetov1 , D. Islamgulov1 , N. Ryabchikova2 , E. Khusnutdinova1 ;<br />
1 2 Institute <strong>of</strong> Biochemistry and <strong>Genetics</strong> RAS, Ufa, Russian Federation, Bashkir<br />
Medical State University, Ufa, Russian Federation.<br />
MicroRNAs are noncoding RNAs that regulate many cellular functions<br />
including cell proliferation, differentiation and apoptosis. They attenuate<br />
gene expression by pairing with the 3’ UTR <strong>of</strong> target transcripts<br />
inducing RNA cleavage or translational inhibition. These small regulatory<br />
molecules are central to various physiologic processes and their<br />
disruption is associated with human diseases, particularly mental retardation.<br />
The purpose <strong>of</strong> this study was to investigate miRNAs-105 role in the<br />
development <strong>of</strong> nonsyndromic mental retardation (MR). We analyzed<br />
rs10238918 SNP located in a miRNA-105 binding site <strong>of</strong> 3’UTR <strong>of</strong><br />
NeuroD6 gene in nonsyndromic MR patients and control group. Neu-<br />
roD6 is a member <strong>of</strong> the NeuroD family <strong>of</strong> basic helix-loop-helix (bHLH)<br />
transcription factors. It activates E box-dependent transcription in collaboration<br />
with TCF3/E47 and is a trans-acting factor involved in the<br />
development and maintenance <strong>of</strong> the mammalian nervous system.<br />
The studied groups included 144 male patients with nonsyndromic<br />
MR (ICD-10) divided into two groups: severe and mild MR and 120<br />
healthy controls. Genomic DNA was extracted from peripheral blood<br />
leukocytes by standard phenol/chlor<strong>of</strong>orm method. Genotyping was<br />
performed by the PCR-RFLP technique.<br />
Significant differences in G allele frequency have been found between<br />
patients with severe form MR and mild form (OR=2.4; CI95%=1.1-5.4),<br />
(chi2=4.4; p=0.03; df=1). The frequency <strong>of</strong> G allele in group <strong>of</strong> patients<br />
with severe MR was 32.1%, which is higher than in mild MR (16.6%).<br />
One <strong>of</strong> explanations <strong>of</strong> these differences could be that G* allele is involved<br />
in formation <strong>of</strong> the binding site to miRNA-105 thus probably<br />
suppressing the expression <strong>of</strong> NeuroD6 gene.<br />
P02.198<br />
molecular characterization <strong>of</strong> the promoters <strong>of</strong> the X-linked<br />
mental retardation gene JARiD1c and additional members <strong>of</strong> the<br />
JARiD1 gene family<br />
L. R. Jensen, M. Schlicht, B. Lipkowitz, H. H. Ropers, A. W. Kuss;<br />
Max Planck Institute for Molecular <strong>Genetics</strong>, Berlin, Germany.<br />
X-linked mental retardation (XLMR) is genetically heterogeneous disorder<br />
affecting approximately 2 in 1000 males. Causative mutations<br />
have been found in over 100 different genes, but a significant proportion<br />
<strong>of</strong> the cases are still without molecular diagnosis. The majority <strong>of</strong><br />
mutations were so far detected in the protein coding regions <strong>of</strong> X-chromosomal<br />
genes. However, sequence changes in regulatory regions<br />
may result in similarly detrimental effects by influencing the transcription<br />
efficiency <strong>of</strong> the respective genes.<br />
Therefore one can assume that part <strong>of</strong> the unsolved cases <strong>of</strong> XLMR<br />
may be due to promoter mutations. Thus, it is necessary to identify<br />
functional promoter elements in known XLMR-genes in order to determine<br />
where sequence changes can have functional consequences.<br />
Furthermore, the identification <strong>of</strong> factors involved in the transcription<br />
<strong>of</strong> these genes is also a way to find additional genes with a putative<br />
role in MR. Therefore we investigated the promoter region <strong>of</strong> one <strong>of</strong><br />
the more frequently mutated XLMR-genes, JARID1C, for functionally<br />
relevant sequences.<br />
As JARID1C encodes a transcription factor, mutations in target promoters<br />
might also cause MR. Thus, having evidence <strong>of</strong> regulatory<br />
interplay between JARID1C and its homolog JARID1B, we included<br />
JARID1B as well as the other JARID1 family members (JARID1A and<br />
JARID1D) in our study. Using a dual-luciferase reporter assay to measure<br />
the activity <strong>of</strong> different parts <strong>of</strong> the 5’-flanking regions <strong>of</strong> these<br />
genes in HEK and SH-SY-5Y cells, we defined regions that are important<br />
for transcriptional activity in all four JARID1 genes.<br />
P02.199<br />
towards understanding the pathogenetic mechanism <strong>of</strong> PQBP1<br />
mutations in X-linked mental retardation<br />
L. Musante, S. Kunde, H. Ropers, V. M. Kalscheuer;<br />
Max-Planck-Institute for Molecular <strong>Genetics</strong>, Berlin, Germany.<br />
We have found that mutations in the polyglutamine binding protein 1<br />
(PQBP1) gene cause X-linked mental retardation. Identical and similar<br />
mutations result in high clinical variability, ranging from moderate mental<br />
retardation to much more severe forms, including microcephaly,<br />
short stature and spasticity. More recently we have begun to unravel<br />
the pathomechanism <strong>of</strong> this disease and have found that PQBP1 mutant<br />
transcripts with a premature stop codon are partially degraded<br />
by nonsense mediated mRNA decay (NMD) and that PQBP1 mutations<br />
cause nonsense-associated altered splicing (NAS). Interestingly,<br />
some <strong>of</strong> the mutations resulted in an upregulation <strong>of</strong> naturally existing<br />
PQBP1 protein is<strong>of</strong>orms. Additional studies demonstrated that the<br />
PQBP1 protein is part <strong>of</strong> a large multiprotein complex containing RNAbinding<br />
proteins that are established components <strong>of</strong> RNA granules and<br />
play distinct roles in post-transcriptional RNA regulation and metabolism.<br />
Interestingly, we have found that PQBP1 is present in dendritic<br />
shafts <strong>of</strong> primary cortical neurons in discrete granular structures and<br />
co-localises with newly found interacting proteins in these granules.<br />
Remarkably, a fraction <strong>of</strong> the PQBP1-containing granules co-localised<br />
with the fragile X-mental retardation protein. Taken together, our find-