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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Molecular basis <strong>of</strong> Mendelian disorders<br />
Twelve individuals were classified as affected after determine a downward<br />
herniation <strong>of</strong> cerebellar tonsils <strong>of</strong> ≥3mm through the foramen<br />
magnum and a volume reduction <strong>of</strong> the posterior fossa in a MRI sagittal<br />
view. After carrying out cytogenetic analysis to rule out major chromosomal<br />
rearrangements, a single nucleotide polymorphism (SNP)based,<br />
0.62cM density genomewide scan was performed in the 21 first<br />
recruited individuals.<br />
Results: Preliminary linkage analysis considering 21 individuals revealed<br />
a disease locus in a 4.3Mb region on 16q13.3 with a maximum<br />
multipoint parametric LOD score <strong>of</strong> 3.109. Several candidate genes<br />
map to this region. Further analysis will include ten recently recruited<br />
individuals and additional microsatellite markers.<br />
Conclusions: A genetic locus in CMI has been described, underscoring<br />
the monogenic character <strong>of</strong> the disorder in some families. Elucidation<br />
<strong>of</strong> the putative disease-causing gene in 16p13 awaits further investigation.<br />
P12.033<br />
Genetic Heterogeneity <strong>of</strong> Geleophysic Dysplasia<br />
C. Le G<strong>of</strong>f 1 , N. Dagoneau 1 , P. Stephan 1 , I. Diebold-Pressac 1 , V. Drouin-Garraud<br />
2 , R. Hennekam 3 , S. Mansour 4 , G. Mortier 5 , M. Splitt 6 , A. Superti-Furga 7 , S.<br />
Unger 7 , M. Le Merrer 1 , A. Munnich 1 , V. Cormier-Daire 1,8 ;<br />
1 INSERM, Paris, France, 2 Hôpital Charles Nicolle, Rouen, France, 3 Academic<br />
Medical Center, Amsterdam, The Netherlands, 4 St George’s university <strong>of</strong> London,<br />
London, United Kingdom, 5 Ghent University Hospital, Ghent, Belgium,<br />
6 Institute <strong>of</strong> <strong>Human</strong> <strong>Genetics</strong>, Newcastle, United Kingdom, 7 Department <strong>of</strong><br />
Pediatrics, University <strong>of</strong> Freiburg, Freiburg, Germany, 8 Université Paris Descartes,<br />
Paris, France.<br />
Geleophysic dysplasia (OMIM 231050, GD) is an autosomal recessive<br />
disorder characterized by short stature, small hands and feet, coneshaped<br />
epiphyses, delayed bone age and shortened tubular bones.<br />
Patients present with a progressive cardiac disease with dilation and<br />
thickening <strong>of</strong> the pulmonary, aortic or mitral valves <strong>of</strong>ten leading to<br />
death before 5 years <strong>of</strong> age. Studying six GD families, we mapped the<br />
disease locus gene on chromosome 9q34.2 and identified four distinct<br />
misense mutations and a nonsense mutation in the A Disintegrin And<br />
Metalloproteinase with Thrombospondin repeats- like 2 gene (ADAMT-<br />
SL2). The ADAMTS-like subfamily comprises proteins homologous to<br />
the ADAMTS ancillary domains but lacking the protease domain and<br />
hence lacking catalytic activity. Their functions are yet unknown. Using<br />
a yeast two hybrid screen, we identify Latent TGFβ Binding Protein<br />
1 (LTBP1) as a partner <strong>of</strong> ADAMTSL2. We also found a higher level<br />
<strong>of</strong> active TGFβ and an enhanced level <strong>of</strong> phoshorylated SMAD2 in<br />
GD fibroblasts allowing us to conclude at an enhanced TGFβ signalling.<br />
Following this initial study, we have collected the samples <strong>of</strong> 18<br />
additional GD families and identified ADAMTSL2 mutations in 6/18<br />
comprising 4 novel mutations. We do not find any distinctive clinical<br />
feature between patients with or without ADAMTSL2 mutation. Finally,<br />
we also found an increase TGFβ level in non mutated ADAMTSL2 fibroblasts.<br />
We conclude that GD is a clinically homogenous but genetically<br />
heterogeneous condition. On going studies will hopefully lead to<br />
the identification <strong>of</strong> another disease gene presumably also involved in<br />
the bioavailability <strong>of</strong> TFGβ.<br />
P12.034<br />
DNA-diagnostics <strong>of</strong> choroideremia in Russian family<br />
O. V. Khlebnikova 1 , S. V. Gudzenko 1 , N. A. Beklemitcheva 2 , A. V. Polyakov 1 ;<br />
1 1- Research Centre for Medical <strong>Genetics</strong>, Russian Academy <strong>of</strong> Medical Sciences,<br />
Moscow, Russian Federation, 2 2- Moscow Research Institute <strong>of</strong> Eye<br />
Diseases, Moscow, Russian Federation.<br />
Choroideremia - is a congenital X-linked ocular disease characterized<br />
by the degeneration <strong>of</strong> the choriocapillaris, the retinal pigment<br />
epithelium and the photoreceptor <strong>of</strong> the eye. The disorder leads to the<br />
progressive loss <strong>of</strong> vision beginning at an early age resulting from the<br />
complete atrophy <strong>of</strong> the choroid and retina. The CHM gene responsible<br />
for choroideremia, is located on Xq21.2, contains 15 exons and<br />
encodes a protein, the Rab escort protein-1 (REP1), which is involved<br />
in membrane trafficking. Currently, there are about 110 mutations in<br />
CHM gene, and these are all nonsense, frameshift or splice site mutations<br />
leading to choroideremia.<br />
The purpose <strong>of</strong> our study was elaboration <strong>of</strong> DNA-diagnostics <strong>of</strong> choroideremia<br />
in affected Russian patient. Sequencing analysis <strong>of</strong> all exons<br />
and intron-exon junctions <strong>of</strong> CHM in affected man showed a previ-<br />
ously described nonsense mutation Arg253Stop (c. 757C>T) in exon 6<br />
<strong>of</strong> CHM. Restriction analysis performed in a sister <strong>of</strong> the patient, who<br />
has small clinical presentations <strong>of</strong> choroideremia, detected mutation<br />
Arg253Stop (c. 757C>T) in heterozygous state. Thus the given DNAanalysis<br />
results revealed a disease-causing mutation Arg253Stop (c.<br />
757C>T) and confirm the diagnosis “choroideremia” in the clinical<br />
case.<br />
P12.035<br />
Functional analysis <strong>of</strong> chronic pancreatitis-associated 5‘<br />
regulatory variants in the pancreatic secretory trypsin inhibitor<br />
(sPiNK1) gene<br />
A. Boulling, J. M. Chen, C. Férec;<br />
INSERM U613, Brest, France.<br />
Introduction: The SPINK1 gene, which encodes the pancreatic secretory<br />
trypsin inhibitor, is one <strong>of</strong> the major genes predisposing to chronic<br />
pancreatitis. To date, a dozen <strong>of</strong> variations have been described in the<br />
5’ regulatory region (RR) <strong>of</strong> SPINK1 but their functional effects remain<br />
unknown. The aim <strong>of</strong> this study was to systematically characterize all<br />
these currently known 5’ RR variants.<br />
Method: The wild-type 5’ RR <strong>of</strong> SPINK1 was firstly cloned into the<br />
pGL3-Basic Luciferase Reporter Vector. All the 5’ RR variations in the<br />
SPINK1 gene were then introduced into the pGL3-SPINK1 construct,<br />
respectively, by means <strong>of</strong> site-directed mutagenesis. SPINK1 promoter<br />
activities were determined in human pancreatic Colo-357 cells. Functional<br />
relevance <strong>of</strong> some variants was further evaluated by EMSA.<br />
Results: The 5’ RR variations can be divided into three categories in<br />
terms <strong>of</strong> luciferase expression, which correlated well with clinical findings.<br />
The variants that caused a decreased expression <strong>of</strong>ten show<br />
consistent disease association among different studies whilst those<br />
that had no effect on expression <strong>of</strong>ten show equal allele distribution<br />
between patients and controls. The variants that caused an increased<br />
expression are, in fact, in cis with a known disease-causing mutation.<br />
EMSA assay demonstrated that variations located in well defined regulatory<br />
motifs affected protein-DNA interactions.<br />
Conclusion: This work was the first to assess the functional impact<br />
<strong>of</strong> the 5’-RR’s SPINK1 variations. Our finding clarified the role <strong>of</strong> the<br />
diverse SPINK1 5’ RR variants in the etiology <strong>of</strong> chronic pancreatitis<br />
and resulted in a better understanding <strong>of</strong> the genotype/phenotype relationship.<br />
P12.036<br />
Genetic background <strong>of</strong> primary ciliary dyskinesia in Polish<br />
patients - search for mutations in candidate genes<br />
E. Zietkiewicz 1,2 , U. Skrzypczak 1 , K. Voelkel 1 , B. Nitka 1 , E. Rutkiewicz 1 , A.<br />
Pogorzelski 3 , M. Witt 1,4 ;<br />
1 Department <strong>of</strong> Molecular and Clinical <strong>Genetics</strong>, Institute <strong>of</strong> <strong>Human</strong> <strong>Genetics</strong>,<br />
Polish Academy <strong>of</strong> Sciences, Poznan, Poland, 2 Supported by, Kbn 3po5e 038-<br />
24; pbz kbn 122/p05-1; nn401-277534, Poland, 3 Institute <strong>of</strong> Tuberculosis and<br />
Lung Diseases, Pediatric Section, Rabka, Poland, 4 International Institute <strong>of</strong><br />
Molecular and Cell Biology, Warszawa, Poland.<br />
The study group comprises families with Kartagener syndrome (KS)<br />
and CDO (ciliary dysfunction only). molecular analysis <strong>of</strong> the genes<br />
involved in PcD pathogenesis. DNAH . Sixty-eight families were<br />
analyzed for the consistency in the inheritance <strong>of</strong> neutral intragenic<br />
SNPs and the disease phenotype. In total, 109 PCD families were<br />
screened for the presence <strong>of</strong> mutations in DNAH5 exons using SSCP/<br />
heteroduplex method. In 77 (<strong>of</strong> 79) exons analyzed, we identified 13<br />
STOP mutations (including four already reported) and 11 missense not<br />
found in the control Polish population. Four mutations (3 STOPs, also<br />
found in <strong>European</strong> patients, and one missense in exon 32 not reported<br />
before) were found in more than one family; haplotype background<br />
analysis indicated common origin for each <strong>of</strong> these repetitive mutations.<br />
DNAI . The search for mutations in DNAI1 was conducted in 113<br />
families without DNAH5 mutations. Among 18 (<strong>of</strong> 20) exons examined,<br />
four harbored mutations (three reported and two newly found). The<br />
most frequent were: insertion in intron 1 and missense in exon 17,<br />
previously reported among <strong>European</strong> patients. Mutations in DNAH5<br />
and DNAI1 are responsible for PCD/KS in at least 20% and 8% Polish<br />
families, respectively, all with ODA defects. Genetic background <strong>of</strong><br />
atypically inherited PcD. Two families with overlapping X-linked RP<br />
and PCD symptoms were examined. In one, a mutation in exon 2 <strong>of</strong><br />
the XL-RPGR gene has been identified and shown to cause aberrant