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Sylvie Jaillard,
Joris Andrieux,
Ghislaine Plessis,
Ana C.V. Krepischi,
Josette Lucas,
Véronique David,
Marine Le Brun,
Debora R. Bertola,
Albert David,
Marc-Antoine Belaud-Rotureau,
Jean Mosser,
Leila Lazaro,
Catherine Treguier,
Carla Rosenberg,
Sylvie Odent,
Christèle Dubourg
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Gaelle Thierry,
Claire Bénéteau,
Olivier Pichon,
Elisabeth Flori,
Bertrand Isidor,
Françoise Popelard,
Marie-Ange Delrue,
Laetitia Duboscq-Bidot,
Ann-Charlotte Thuresson,
Bregje W M van Bon, [......],
Bassim Tou,
Marie-Pierre Quéré,
Cecilia Soussi-Zander,
Annick Toutain,
Didier Lacombe,
Benoit Arveiler,
Bert B A de Vries,
Philippe Jonveaux,
Albert David,
Cédric Le Caignec
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ABSTRACT: Patients with a submicroscopic deletion at 1q43q44 present with intellectual disability (ID), microcephaly, craniofacial anomalies, seizures, limb anomalies, and corpus callosum abnormalities. However, the precise relationship between most of deleted genes and the clinical features in these patients still remains unclear. We studied 11 unrelated patients with 1q44 microdeletion. We showed that the deletions occurred de novo in all patients for whom both parents' DNA was available (10/11). All patients presented with moderate to severe ID, seizures and non-specific craniofacial anomalies. By oligoarray-based comparative genomic hybridization (aCGH) covering the 1q44 region at a high resolution, we obtained a critical deleted region containing two coding genes-HNRNPU and FAM36A-and one non-coding gene-NCRNA00201. All three genes were expressed in different normal human tissues, including in human brain, with highest expression levels in the cerebellum. Mutational screening of the HNRNPU and FAM36A genes in 191 patients with unexplained isolated ID did not reveal any deleterious mutations while the NCRNA00201 non-coding gene was not analyzed. Nine of the 11 patients did not present with microcephaly or corpus callosum abnormalities and carried a small deletion containing HNRNPU, FAM36A, and NCRNA00201 but not AKT3 and ZNF238, two centromeric genes. These results suggest that HNRNPU, FAM36A, and NCRNA00201 are not major genes for microcephaly and corpus callosum abnormalities but are good candidates for ID and seizures.
American Journal of Medical Genetics Part A 06/2012; 158A(7):1633-40. · 2.39 Impact Factor
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ABSTRACT: The genomic organization of the LEPR gene is complex and generates three independent transcripts whose respective functions are still poorly understood.
We describe here a 7-year old patient with a homozygous 80 kb deletion in the chromosomal 1p31.3 region with early onset obesity, mental retardation and epilepsy. The deleted region comprises the proximal promoter and exons 1 and 2 of the LEPR gene and exons 5 to 19 of the DNAJC6 gene. The deletion leads to the deficiency of all canonical OB-R isoforms but maintains the B219 OB-R short isoforms controlled by the preserved second LEPR promoter. The DNAJC6 gene encodes auxilin-1, a protein required for clathrin-dependent recycling of synaptic vesicles in neurons that is possibly at the origin of the mental retardation and epilepsy phenotype. The obese phenotype and the absence of signaling-competent OB-R are consistent with previously reported individuals with OB-R deficiency. The deletion eliminates an additional transcript of the LEPR gene that encodes endospanin-1, a protein that has been genetically and biochemically linked to OB-R function.
Our study confirms the phenotype of individuals with OB-R deficiency and postulates the effects of auxilin-1 deficiency (mental retardation/epilepsy) and endospanin-1 deficiency (OB-R specific functions) in humans.
Molecular Genetics and Metabolism 05/2012; 106(3):345-50. · 3.19 Impact Factor
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Sandra Mercier,
Christèle Dubourg,
Nicolas Garcelon,
Boris Campillo-Gimenez,
Isabelle Gicquel,
Marion Belleguic,
Leslie Ratié,
Laurent Pasquier,
Philippe Loget,
Claude Bendavid, Sylvie Jaillard,
Lucie Rochard,
Chloé Quélin,
Valérie Dupé,
Véronique David,
Sylvie Odent
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ABSTRACT: Holoprosencephaly (HPE) is the most common forebrain defect in humans. It results from incomplete midline cleavage of the prosencephalon.
A large European series of 645 HPE probands (and 699 relatives), consisting of 51% fetuses and 49% liveborn children, is reported.
Mutations in the four main genes involved in HPE (SHH, ZIC2, SIX3, TGIF) were identified in 25% of cases. The SHH, SIX3, and TGIF mutations were inherited in more than 70% of these cases, whereas 70% of the mutations in ZIC2 occurred de novo. Moreover, rearrangements were detected in 22% of the 260 patients screened by array comparative genomic hybridisation. 15 probands had two mutations providing additional support for the 'multiple-hit process' in HPE. There was a positive correlation between the severity of the brain malformation and facial features for SHH, SIX3, and TGIF, but no such correlation was found for ZIC2 mutations. The most severe HPE types were associated with SIX3 and ZIC2 mutations, whereas microforms were associated with SHH mutations. The study focused on the associated brain malformations, including neuronal migration defects, which predominated in individuals with ZIC2 mutations, and neural tube defects, which were frequently associated with ZIC2 (rachischisis) and TGIF mutations. Extracraniofacial features were observed in 27% of the individuals in this series (up to 40% of those with ZIC2 mutations) and a significant correlation was found between renal/urinary defects and mutations of SHH and ZIC2.
An algorithm is proposed based on these new phenotype-genotype correlations, to facilitate molecular analysis and genetic counselling for HPE.
Journal of Medical Genetics 09/2011; 48(11):752-60. · 6.36 Impact Factor
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Sébastien Jacquemont,
Alexandre Reymond,
Flore Zufferey,
Louise Harewood,
Robin G Walters,
Zoltán Kutalik,
Danielle Martinet,
Yiping Shen,
Armand Valsesia,
Noam D Beckmann, [......],
Joris Andrieux,
Xavier Estivill,
James F Gusella,
Omar Gustafsson,
Andres Metspalu,
Stephen W Scherer,
Kari Stefansson,
Alexandra I F Blakemore,
Jacques S Beckmann,
Philippe Froguel
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ABSTRACT: Both obesity and being underweight have been associated with increased mortality. Underweight, defined as a body mass index (BMI) ≤ 18.5 kg per m(2) in adults and ≤ -2 standard deviations from the mean in children, is the main sign of a series of heterogeneous clinical conditions including failure to thrive, feeding and eating disorder and/or anorexia nervosa. In contrast to obesity, few genetic variants underlying these clinical conditions have been reported. We previously showed that hemizygosity of a ∼600-kilobase (kb) region on the short arm of chromosome 16 causes a highly penetrant form of obesity that is often associated with hyperphagia and intellectual disabilities. Here we show that the corresponding reciprocal duplication is associated with being underweight. We identified 138 duplication carriers (including 132 novel cases and 108 unrelated carriers) from individuals clinically referred for developmental or intellectual disabilities (DD/ID) or psychiatric disorders, or recruited from population-based cohorts. These carriers show significantly reduced postnatal weight and BMI. Half of the boys younger than five years are underweight with a probable diagnosis of failure to thrive, whereas adult duplication carriers have an 8.3-fold increased risk of being clinically underweight. We observe a trend towards increased severity in males, as well as a depletion of male carriers among non-medically ascertained cases. These features are associated with an unusually high frequency of selective and restrictive eating behaviours and a significant reduction in head circumference. Each of the observed phenotypes is the converse of one reported in carriers of deletions at this locus. The phenotypes correlate with changes in transcript levels for genes mapping within the duplication but not in flanking regions. The reciprocal impact of these 16p11.2 copy-number variants indicates that severe obesity and being underweight could have mirror aetiologies, possibly through contrasting effects on energy balance.
Nature 08/2011; 478(7367):97-102. · 36.28 Impact Factor
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Sylvie Jaillard,
Joris Andrieux,
Ghislaine Plessis,
Ana C.V. Krepischi,
Josette Lucas,
Véronique David,
Marine Le Brun,
Debora R. Bertola,
Albert David,
Marc-Antoine Belaud-Rotureau,
Jean Mosser,
Leila Lazaro,
Catherine Treguier,
Carla Rosenberg,
Sylvie Odent,
Christèle Dubourg
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ABSTRACT: Array-CGH enables the detection of submicroscopic chromosomal deletions and duplications and leads to an accurate delineation of the imbalances, raising the possibility of genotype to phenotype and mapping minimal critical regions associated with particular patterns of clinical features. We report here on four patients sharing common clinical features (psychomotor retardation, coarse facies and ocular anomalies), with proximal 5q deletions identified by oligo array-CGH. The deletions range from 5.75 to 17.26-Mb in size and occurred de novo. A common 2.63-Mb region between the deletions described here can be defined in 5q12.1 (59,390,122–62,021,754 bp from 5pter, hg18) and includes 12 genes. Among them, KIF2A, which encodes a kinesin superfamily protein, is a particularly interesting candidate for the phenotype, as it suppresses the growth of axonal collateral branches and is involved in normal brain development. Ocular defects, albeit unspecific, seem to be common in the 5q12.1 deletion. Identification of additional cases of deletions involving the 5q12.1 region will allow more accurate genotype–phenotype correlations. © 2011 Wiley-Liss, Inc.
American Journal of Medical Genetics Part A 03/2011; 155(4):725 - 731. · 2.39 Impact Factor
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ABSTRACT: The expression of human leukocyte antigen (HLA)-G on cytotrophoblast cells contributes to maternal-fetal tolerance. Soluble forms of HLA-G (sHLA-G) can be detected in amniotic fluid (AF) and a decrease of sHLA-G is known to be correlated to fetal loss. In this work we investigated the role of sHLA-G in the transplacental passage of the protozoan parasite Toxoplasma gondii, responsible for congenital toxoplasmosis in about 30% of fetuses when primary infection (PI) occurs during pregnancy. We determined the sHLA-G concentration in 61 AF from women with PI and 24 controls. Our results showed higher sHLA-G levels in AF from PI than in controls (p<0.001). Moreover sHLA-G level from congenitally infected fetuses (n=12) was higher than in fetus in whom congenital infection was ruled out (n=49, p<0.05). These data suggest that sHLA-G could participate in immunomodulation necessary to avoid fetal loss due to Toxoplasma infection, but that over-expression could favor congenital transmission.
Clinical Immunology 02/2011; 138(2):129-34. · 4.05 Impact Factor
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Christèle Dubourg,
Damien Sanlaville,
Martine Doco-Fenzy,
Cédric Le Caignec,
Chantal Missirian, Sylvie Jaillard,
Caroline Schluth-Bolard,
Emilie Landais,
Odile Boute,
Nicole Philip, [......],
Dominique Martin-Coignard,
Catherine Vincent-Delorme,
Isabelle Mortemousque,
Bénédicte Duban-Bedu,
Sèverine Drunat,
Mylène Beri,
Jean Mosser,
Sylvie Odent,
Véronique David,
Joris Andrieux
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ABSTRACT: Chromosome 17q21.31 microdeletion was one of the first genomic disorders identified by chromosome microarrays. We report here the clinical and molecular characterization of a new series of 14 French patients with this microdeletion syndrome. The most frequent clinical features were hypotonia, developmental delay and facial dysmorphism, but scaphocephaly, prenatal ischemic infarction and perception deafness were also described. Genotyping of the parents showed that the parent from which the abnormality was inherited carried the H2 inversion polymorphism, confirming that the H2 allele is necessary, but not sufficient to generate the 17q21.31 microdeletion. Previously reported molecular analyses of patients with 17q21.31 microdeletion syndrome defined a 493 kb genomic fragment that was deleted in most patients after taking into account frequent copy number variations in normal controls, but the deleted interval was significantly smaller (205 kb) in one of our patients, encompassing only the MAPT, STH and KIAA1267 genes. As this patient presents the classical phenotype of 17q21.31 syndrome, these data make it possible to define a new minimal critical region of 160.8 kb, strengthening the evidence for involvement of the MAPT gene in this syndrome.
European journal of medical genetics 11/2010; 54(2):144-51. · 1.57 Impact Factor
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Sylvie Jaillard,
Philippe Loget,
Josette Lucas,
Christèle Dubourg,
Gwenaelle Le Bouar,
Florence Demurger,
Isabelle Bertorello,
Véronique David,
Patrice Poulain,
Sylvie Odent,
Marc-Antoine Belaud-Rotureau
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ABSTRACT: We report the case of a female patient exhibiting multiple congenital malformations including diaphragmatic hernia and heart defect. Cytogenetic studies (including karyotype, FISH and array-CGH) showed a de novo terminal deletion (6.9 Mb) on chromosome 15 in association with a recombinant X chromosome bearing a 9-Mb Xp duplication and a 46-Mb Xq deletion distal to XIST. The recombinant X chromosome was caused by a maternal inv(X)(p22.31q22.3). The X chromosome inactivation pattern was skewed in the patient suggesting a possible inactivation of the recombinant X chromosome. Considering these results, the phenotype was linked to the de novo terminal 15q deletion. These results strengthen the assumption that array-CGH should be applied to each fetus/newborn with multiple congenital malformations.
European journal of medical genetics 11/2010; 54(2):186-8. · 1.57 Impact Factor
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Sylvie Jaillard,
Séverine Drunat,
Claude Bendavid,
Azzedine Aboura,
Amandine Etcheverry,
Hubert Journel,
Andrée Delahaye,
Laurent Pasquier,
Dominique Bonneau,
Annick Toutain, [......],
Brigitte Benzacken,
Dominique Martin-Coignard,
Catherine Henry,
Albert David,
Josette Lucas,
Jean Mosser,
Véronique David,
Sylvie Odent,
Alain Verloes,
Christèle Dubourg
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ABSTRACT: Array-CGH has revealed a large number of copy number variations (CNVs) in patients with multiple congenital anomalies and/or mental retardation (MCA/MR). According to criteria recently listed, pathogenicity was clearly suspected for some CNVs but benign CNVs, considered as polymorphisms, have complicated the interpretation of the results. In this study, genomic DNAs from 132 French patients with unexplained mental retardation were analysed by genome wide high-resolution Agilent 44K oligonucleotide arrays. The results were in accordance with those observed in previous studies: the detection rate of pathogenic CNVs was 14.4%. A non-random involvement of several chromosomal regions was observed. Some of the microimbalances recurrently involved regions (1q21.1, 2q23.1, 2q32q33, 7p13, 17p13.3, 17p11.2, 17q21.31) corresponding to known or novel syndromes. For all the pathogenic CNVs, further cases are needed to allow more accurate genotype-phenotype correlations underscoring the importance of databases to group patients with similar molecular data.
European journal of medical genetics 10/2009; 53(2):66-75. · 1.57 Impact Factor
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N Le Meur,
M Holder-Espinasse, S Jaillard,
A Goldenberg,
S Joriot,
P Amati-Bonneau,
A Guichet,
M Barth,
A Charollais,
H Journel,
S Auvin,
C Boucher,
J-P Kerckaert,
V David,
S Manouvrier-Hanu,
P Saugier-Veber,
T Frébourg,
C Dubourg,
J Andrieux,
D Bonneau
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ABSTRACT: Over the last few years, array-comparative genomic hybridisation (CGH) has considerably improved our ability to detect cryptic unbalanced rearrangements in patients with syndromic mental retardation.
Molecular karyotyping of six patients with syndromic mental retardation was carried out using whole-genome oligonucleotide array-CGH.
5q14.3 microdeletions ranging from 216 kb to 8.8 Mb were detected in five unrelated patients with the following phenotypic similarities: severe mental retardation with absent speech, hypotonia and stereotypic movements. Facial dysmorphic features, epilepsy and/or cerebral malformations were also present in most of these patients. The minimal common deleted region of these 5q14 microdeletions encompassed only MEF2C, the gene for a protein known to act in brain as a neurogenesis effector, which regulates excitatory synapse number. In a patient with a similar phenotype, an MEF2C nonsense mutation was subsequently identified.
Taken together, these results strongly suggest that haploinsufficiency of MEF2C is responsible for severe mental retardation with stereotypic movements, seizures and/or cerebral malformations.
Journal of Medical Genetics 08/2009; 47(1):22-9. · 6.36 Impact Factor
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Caroline Schluth-Bolard,
Bruno Delobel,
Damien Sanlaville,
Odile Boute,
Jean-Marie Cuisset,
Sylvie Sukno,
Audrey Labalme,
Bénédicte Duban-Bedu,
Ghislaine Plessis, Sylvie Jaillard, [......],
Josette Lucas,
Sylvie Odent,
Laurent Pasquier,
Henri Copin,
Philippe Latour,
Marie-Pierre Cordier,
Gwenaël Nadeau,
Marianne Till,
Patrick Edery,
Joris Andrieux
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ABSTRACT: Investigations of apparently balanced chromosomal rearrangements in patients with abnormal phenotype by molecular cytogenetics tools, especially by array CGH, revealed a proportion of unsuspected imbalances. It was estimated recently that 40% of apparently balanced de novo translocations with abnormal phenotype were associated with cryptic deletion. We explored 47 unrelated mental retardation patients carrying an apparently balanced chromosomal rearrangement with high-resolution oligonucleotides arrays. We included 33 de novo cases (21 translocations, 7 inversions and 5 complex chromosomal rearrangements (CCR)) and 14 inherited cases (7 translocations, 5 inversions and 2 CCR). Twenty of the 47 cases (42.6%) carried a cryptic deletion ranging from 60 kb to 15.37 Mb. It concerned 16/33 de novo rearrangements (8/21 translocations, 4/7 inversions and 4/5 CCR) and 4/14 inherited rearrangements (1/7 translocations, 2/5 inversions and 1/2 CCR). The proportion of imbalances was not statistically different between de novo and inherited cases. Our results support that about 40% apparently balanced chromosomal rearrangements with abnormal phenotype are in fact imbalanced and that these rearrangements should be systematically investigated by array CGH independently of their de novo or inherited character.
European journal of medical genetics 07/2009; 52(5):291-6. · 1.57 Impact Factor
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Chloé Quélin,
Claude Bendavid,
Christèle Dubourg,
Céline de la Rochebrochard,
Josette Lucas,
Catherine Henry, Sylvie Jaillard,
Philippe Loget,
Laurence Loeuillet,
Didier Lacombe,
Jean-Marie Rival,
Véronique David,
Sylvie Odent,
Laurent Pasquier
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ABSTRACT: 13q deletion is characterized by a wide phenotypic spectrum resulting from a partial deletion of the long arm of chromosome 13. The main clinical features are mental retardation, growth retardation, craniofacial dysmorphy and various congenital defects. Only one recent Italian study was aimed at determining genotype-phenotype correlations among 13q deletions from a group of mainly live born children, using array-CGH and FISH. In order to improve the molecular characterization of 13q monosomy, 12 new patients (9 foetuses and 3 children) were collected based on a cohort of holoprosencephaly (HPE) linked to ZIC2 gene deletion and/or patients with 13q deletion diagnosed by standard karyotype. First, quantitative gene screening using MLPA (Multiplex Ligation dependent Probe Amplification) was performed to look for ZIC2 gene deletion and then, CGH array analysis was carried out using the Agilent Human Genome CGH microarray 4x44K (Agilent Technologies, Santa Clara, USA). All the foetuses had severe cerebral midline malformations associated with a deletion including the ZIC2 gene. We report one patient with Steinfeld phenotype linked to this chromosomal anomaly, and suggest that some of the associations between cerebral midline malformation and limb defects might be related to 13q deletion. Further candidate genes are suspected to explain the malformations associated with cerebral anomalies in the hypothesis of a contiguous gene syndrome: SPRY2 in 13q31.1 is implicated in lens cell proliferation and differentiation for congenital cataract; GPC5 in 13q32 is mainly expressed in the mesenchyme of the developing limb bud for upper limb anomalies.
European journal of medical genetics 11/2008; 52(1):41-6. · 1.57 Impact Factor
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S Jaillard,
C Dubourg,
M Gérard-Blanluet,
A Delahaye,
L Pasquier,
C Dupont,
C Henry,
A-C Tabet,
J Lucas,
A Aboura,
V David,
B Benzacken,
S Odent,
E Pipiras
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ABSTRACT: Genome-wide screening of patients with mental retardation using array comparative genomic hybridisation (CGH) has identified several novel imbalances. With this genotype-first approach, the 2q22.3q23.3 deletion was recently described as a novel microdeletion syndrome. The authors report two unrelated patients with a de novo interstitial deletion mapping in this genomic region and presenting similar "pseudo-Angelman" phenotypes, including severe psychomotor retardation, speech impairment, epilepsy, microcephaly, ataxia, and behavioural disabilities.
The microdeletions were identified by array CGH using oligonucleotide and bacterial artificial chromosome (BAC) arrays, and further confirmed by fluorescence in situ hybridisation (FISH) and semi-quantitative polymerase chain reaction (PCR).
The boundaries and sizes of the deletions in the two patients were different but an overlapping region of about 250 kb was defined, which mapped to 2q23.1 and included two genes: MBD5 and EPC2. The SIP1 gene associated with the Mowat-Wilson syndrome was not included in the deleted genomic region.
Haploinsufficiency of one of the deleted genes (MBD5 or EPC2) could be responsible for the common clinical features observed in the 2q23.1 microdeletion syndrome, and this hypothesis needs further investigation.
Journal of Medical Genetics 10/2008; 46(12):847-55. · 6.36 Impact Factor
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Claude Bendavid,
Christèle Dubourg,
Isabelle Gicquel,
Laurent Pasquier,
Pascale Saugier-Veber,
Marie-Renée Durou, Sylvie Jaillard,
Thierry Frébourg,
Bassem R Haddad,
Catherine Henry,
Sylvie Odent,
Véronique David
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ABSTRACT: Holoprosencephaly (HPE), the most common structural malformation of the forebrain in humans, can be detected early during pregnancy using prenatal ultrasonography . Among foetuses with a normal karyotype, 14% have mutations in the four main HPE genes (SHH, ZIC2, SIX3 and TGIF). Genomic rearrangements have now been implicated in many genetic diseases, so we hypothesized that microdeletions in the major HPE genes may also be common in HPE foetuses with severe phenotype or other associated malformations. We screened the DNA obtained from 94 HPE foetuses with a normal karyotype for the presence of microdeletions involving the four major HPE genes (SHH, ZIC2, SIX3 and TGIF). Thirteen of the foetuses had a point mutation in one of the 4 genes and 81 had no known mutations. Quantitative multiplex PCR of short fluorescent fragments (QMPSF) analysis was used for rapid determination of HPE genes copy numbers and the identified microdeletions were confirmed by real time quantitative PCR, or fluorescent in situ hybridization (FISH) (if a cell line was available). Microdeletions were detected in 8 of 94 foetuses (8.5%) (2 in SHH, 2 in SIX3, 3 in ZIC2 and 1 in TGIF genes), and only among the 81 foetuses with a normal karyotype and no point mutations. These data suggest that microdeletions in the four main HPE genes are a common cause of prenatal HPE, as well as point mutations, and increase the total diagnosis rate close to approximately 22.3% of foetuses with normal karyotype. Detection can be achieved by the QMPSF testing method that proved to be efficient for testing several genes in a single assay.
Human Genetics 04/2006; 119(1-2):1-8. · 5.07 Impact Factor
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Sylvie Jaillard,
Christèle Dubourg,
Marion Gérard-Blanluet,
Andrée Delahaye,
Laurent Pasquier,
Céline Dupont,
Catherine Henry,
Anne-Claude Tabet,
Josette Lucas,
Azzedine Aboura,
Véronique David,
Brigitte Benzacken,
Sylvie Odent,
Eva Pipiras
[show abstract]
[hide abstract]
ABSTRACT: BACKGROUND: Genome-wide screening of patients with mental retardation using array comparative genomic hybridisation (CGH) has identified several novel imbalances. With this genotype-first approach, the 2q22.3q23.3 deletion was recently described as a novel microdeletion syndrome. The authors report two unrelated patients with a de novo interstitial deletion mapping in this genomic region and presenting similar "pseudo-Angelman" phenotypes, including severe psychomotor retardation, speech impairment, epilepsy, microcephaly, ataxia, and behavioural disabilities. METHODS: The microdeletions were identified by array CGH using oligonucleotide and bacterial artificial chromosome (BAC) arrays, and further confirmed by fluorescence in situ hybridisation (FISH) and semi-quantitative polymerase chain reaction (PCR). RESULTS: The boundaries and sizes of the deletions in the two patients were different but an overlapping region of about 250 kb was defined, which mapped to 2q23.1 and included two genes: MBD5 and EPC2. The SIP1 gene associated with the Mowat-Wilson syndrome was not included in the deleted genomic region. DISCUSSION: Haploinsufficiency of one of the deleted genes (MBD5 or EPC2) could be responsible for the common clinical features observed in the 2q23.1 microdeletion syndrome, and this hypothesis needs further investigation.
Journal of medical genetics.
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Claude Bendavid,
Lucie Rochard,
Christèle Dubourg,
Jonathan Seguin,
Isabelle Gicquel,
Laurent Pasquier,
Jaqueline Vigneron,
Annie Laquerrière,
Pascale Marcorelles,
Corinne Jeanne-Pasquier,
Caroline Rouleau, Sylvie Jaillard,
Jean Mosser,
Sylvie Odent,
Véronique David
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ABSTRACT: Holoprosencephaly (HPE) is the most frequent malformation of the brain. To date, 12 different HPE loci and 8 HPE genes have been identified from recurrent chromosomal rearrangements or from the sequencing of genes from Nodal and SHH pathways. Our cohort of HPE patients presents a high genetic heterogeneity. Point mutations were found in SHH, ZIC2, SIX3, and TGIF genes in about 20% of cases (with 10% in SHH). Deletions in these same genes were found in 7.5% of the patients and 4.4% presented with other subtelomeric gain or losses. Consequently, the molecular basis of HPE remains unknown in 70% of our cohorts. To detect new HPE candidate genes, we used array-CGH to refine the previous karyotype based HPE loci map. We analyzed 111 HPE patients with high-performance Agilent oligonucleotidic arrays and found that 28 presented anomalies involving known or new potential HPE loci located on different chromosomes but with poor redundancy. This study showed an impressive rate of 19 patients among 111 with de novo chromosomal anomalies giving evidence that microrearrangements could be a major molecular mechanism in HPE. Additionally, this study opens new insights on HPE candidate genes identification giving an updated HPE candidate loci map.
Human Mutation.