2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
P05.148
Exon resequencing, mutation detection, and copy number
analysis in syndromic oesophageal atresia
M. Storer1 , E. Howard1 , V. Martin2 , G. LeFebvre1 , A. Coffey1 , C. J. Shaw-
Smith1 ;
1 2 Wellcome Trust Sanger Institute, Cambridge, United Kingdom, Institute of
Child Health, London, United Kingdom.
Oesophageal atresia and/or tracheo-oesophageal fistula are common
malformations occurring in approximately 1 in 3500 births . In around
half of cases (syndromic oesophageal atresia, overlapping with the
VACTERL association), there are associated anomalies, cardiac malformations
being the most common . Recently, three separate genes
with a role in syndromic oesophageal atresia have been identified:
those for Feingold syndrome (N-MYC), anophthalmia-oesophagealgenital
(AEG) syndrome (SOX2), and CHARGE syndrome (CHD7) . It
is likely that other genes play a role in foregut development, and dosage
sensitive chromosomal loci presumably harbouring these as yet
unidentified genes have recently been highlighted (refs 1 and 2).
We are collecting DNA samples from patients with syndromic forms of
oesophageal atresia and the VACTERL association . We are analyzing
these samples by exon resequencing in the CHD7, N-MYC, SALL1
and SOX2 genes (additional genes, including FANCB and FANCC are
currently being added to the panel); and by high resolution array-based
comparative genomic hybridization (arrayCGH) . To date, we have analyzed
50 samples . No de novo copy number changes have as yet been
identified. A de novo frame shift mutation has been detected in CHD7
in a single patient with some features of CHARGE syndrome .
By adopting this comprehensive approach to the analysis of a single
malformation, we hope to identify other genes involved in human foregut
development and to continue to provide a research-based service
to the Clinical Genetics community for this patient group .
1 . Shaw-Smith C. J Med Genet . 2006: 43(7):545-54 .
2 . Felix JF, et al Eur J Med Genet . 2007: 50(3):163-75
P05.149
mutational spectrum of the Oral-facial-digital type i syndrome: a
study on a large collection of patients
B. Franco1,2 , C. Prattichizzo1 , M. Macca1,2 , V. Novelli1 , G. Giorgio1 , A. Barra1 ,
OFDI collaborative group;
1 2 Telethon Institute of Genetics and Medicine-TIGEM, Naples, Italy, Department
of Pediatrics, University Federico II, Naples, Italy.
Oral-facial-digital type I (OFDI; MIM 311200) syndrome is a male-lethal
X-linked dominant developmental disorder belonging to the heterogeneous
group of Oral-facial-digital syndrome (OFDS) . OFDI is characterized
by malformations of the face, oral cavity and digits . CNS abnormalities
and cystic kidney disease can also be part of this condition .
This rare genetic disorder is due to mutations in the OFD1 gene that
encodes a centrosome/basal body protein necessary for primary cilium
assembly and for left-right axis determination, thus ascribing OFDI
to the growing number of disorders associated to ciliary dysfunction .
We now report a mutation analysis study in a cohort of 100 unrelated
affected individuals collected worldwide . Putative disease-causing mutations
were identified in 81 patients (81%). We describe 67 different
mutations, 64 of which represent novel mutations, including 36 frameshift,
9 missense, 11 splice-site and 11 nonsense mutations . Most of
them concentrate in exons 3, 8, 9, 12, 13 and 16, suggesting that these
exons may represent mutational hotspots . Phenotypic characterization
of the patients provided a better definition of the clinical features of
OFD type I syndrome . Our results indicate that renal cystic disease is
present in 60% of cases with >18 years of age . Genotype-phenotype
correlation did not reveal significant associations apart for the higharched/cleft
palate most frequently associated to missense and splicesite
mutations . Our results contribute to further expand our knowledge
on the molecular basis of OFD type I syndrome .
P05.150
the Opitz syndrome gene product miD1 assembles a
microtubule-associated ribonucleoprotein complex
B. Aranda Orgilles 1 , A. Trockenbacher 2 , J. Winter 3 , J. Aigner 1 , A. Köhler 2 , E.
Jastrzebska 1 , J. Stahl 4 , R. Schneider 2,3 , S. Schweiger 1,5 ;
1 Max Planck institute for molecular genetics, berlin, Germany, 2 Institute of
Biochemistry, Innsbruck, Austria, 3 Max Planck Institute for molecular genetics,
Berlin, Germany, 4 Max-Delbrueck Center of Molecular Medicine, berlin,
Germany, 5 Medical School, Division of Pathology and Neuroscience, Dundee,
United Kingdom.
Opitz BBB/G syndrome (OS) is a heterogenous malformation syndrome
mainly characterised by hypertelorism and hypospadias . In
addition, patients may present with several other defects of the ventral
midline such as cleft lip and palate and congenital heart defects .
The syndrome-causing gene encodes the X-linked E3 ubiquitin ligase
MID1 that mediates ubiquitin-specific modification and degradation of
the catalytic subunit of the translation regulator protein phosphatase
2A (PP2A) . Here, we show that the MID1 protein also associates with
elongation factor 1α (EF-1α) and several other proteins involved in
mRNA transport and translation, including RACK1, Annexin A2, Nucleophosmin
and proteins of the small ribosomal subunits . Mutant
MID1 proteins as found in OS patients lose the ability to interact with
EF-1α. The composition of the MID1 protein complex was determined
by several independent methods: (1) yeast two-hybrid screening, (2)
immunofluorescence, (3) a biochemical approach involving affinity
purification of the complex, (4) co-fractionation in a microtubule assembly
assay and (5) immunoprecipitation . Moreover, we show that
the cytoskeleton-bound MID1/translation factor complex specifically
associates with G- and U-rich RNAs and incorporates MID1 mRNA,
thus forming a microtubule-associated ribonucleoprotein (RNP) complex
. Our data suggest a novel function of the OS gene product in
directing translational control to the cytoskeleton . The dysfunction of
this mechanism would lead to malfunction of microtubule-associated
protein translation and to the development of OS .
P05.151
Large genomic rearrangements of the OFD gene account for
20 % of patients with Oral-Facial-Digital type 1 syndrome and
negative DNA sequencing analysis
C. Thauvin-Robinet 1,2 , B. Franco 3 , P. Saugier-Veber 4 , N. Gigot 5 , B. Aral 5 , A.
Donzel 5 , L. Van Maldergem 6 , E. Bieth 7 , V. Layet 8 , M. Mathieu 9 , A. Teebi 10 , T.
Morisawa 11 , M. Matsuo 11 , L. Burglen 12 , V. Cormier-Daire 13 , A. Masurel-Paulet 1,2 ,
E. Gautier 14 , F. Huet 15 , J. Teyssier 5 , M. Tosi 4 , T. Frebourg 4 , L. Faivre 1,2 ;
1 centre de génétique, Dijon, France, 2 Centre de Références Maladies Rares
- Anomalies du Développement Embryonnaire et syndromes malformatifs- de
la Région Grand Est, CHU, Dijon, France, 3 Laboratorio di Ricerca, Telethon
Institute of Genetics and Medicine (TIGEM), Napoli, Italy, 4 Laboratoire de génétique
moléculaire, Service de génétique, Faculté de médecine et de pharmacie,
Rouen, France, 5 Laboratoire de Génétique Moléculaire, Hôpital du Bocage,
CHU, Dijon, France, 6 Institut de Pathologie et de Génétique, Loverval, Belgium,
7 Laboratoire de Génétique, CHU Purpan, Toulouse, France, 8 Unité de Cytogénétique
et Génétique médicale, CH, Le Havre, France, 9 Centre de référence
- Anomalies du développement et syndromes malformatifs – de la région Nord,
Département de pédiatrie - Unité de génétique clinique, CHU Hôpital Nord,
Amiens, France, 10 Division of clinical and Metabolic Genetics, The Hospital of
Sick Children, Toronto, ON, Canada, 11 Department of Pediatrics, Kobe University
Graduate School of Medicine, Kobe, Japan, 12 Centre de référence des
malformations et maladies congénitales du cervelet, Service de génétique et
d’embryologie médicales, CHU Hôpital d’Enfants Armand-Trousseau, APHP,
Paris, France, 13 Département de Génétique, Hôpital Necker-Enfants Malades,
APHP, Paris, France, 14 CIC-EC, Hôpital Le Bocage, CHU, Dijon, France, 15 Service
de Pédiatrie 1, Hôpital d’Enfants, CHU, Dijon, France.
Among the oral-facial-digital syndromes, the oral-facial-digital type
1 syndrome (OFD 1) is characterised by X-linked dominant mode of
inheritance . Clinical features include facial dysmorphism with oral,
tooth and distal abnormalities, polycystic kidney disease and central
nervous system malformations . A high clinical overlap exists between
the different types of OFD syndrome . OFD1 DNA sequencing analysis
remains negative in 30 to 50% of cases . We hypothesized that large
genomic rearrangements could account for the majority of these unexplained
cases . A series of 25 index cases (29 patients) with OFD1 phenotype
and normal OFD1 DNA sequencing analysis were screened for
OFD1 rearrangements by QMPSF and relative quantitative real-time
PCR analyses . Five large deletions (exons 1-8, exons 1-14, exons 10-
11, exon 17 and exons 13-23) were identified in five index cases, accounting
for 20 % of negative mutation patients after DNA sequencing .
Among the remaining negative index cases, a family history compatible
with dominant X-linked inheritance was found in one case only . Using
DNA sequencing, QMPSF and relative quantitative real-time PCR
analyses, the OFD1 alteration detection level remains incomplete .
However, it is likely that sporadic patients without OFD1 alterations