Cartographie physique par hybridation in situ en fluorescence : Application à l'étude de remaniements du chromosome X associés à des pathologies

Not availableNon disponibl

High resolution microarray investigation in patients with developmental delay and/or multiple congenital anomalies: delineation of new candidates regions on the human genome

Constitutional chromosomal imbalance has been recognized, for a long time, as an important cause of congenital and developmental abnormalities including developmental delay (DD), intellectual disability (ID), autism spectrum disorders (ASD) and/or multiple congenital anomalies (MCA). The high-resolution array-based comparative genome hybridization (array CGH) has led to the detection of large numbers of copy number variants (CNVs) in patients with developmental delay and/or multiple congenital anomalies, as well as in healthy individuals, that challenges the interpretation of the clinical significance of detected CNVs in patients. The objective of this work is to present a retrospective review of array-CGH data of 482 children with unexplained intellectual disability +/- congenital abnormalities. This work reinforces the current status practice of array-based technology use for postnatal diagnosis and supports that it will replace standard cytogenetics as a first-line test for clinical evaluation in the population with ID +/- congenital abnormalities

Mild intellectual disability associated with a progeny of father-daughter incest: genetic and environmental considerations

We report the case of a 34-year-old female resulting from a father-daughter sexual abuse and presenting a phenotype of mild intellectual disability with minor dysmorphic features. Karyotyping showed a normal 46, XX constitution. Array-based comparative genomic hybridization (array-CGH) revealed a heterozygote 320kb 6p22.3 microdeletion in the proband, encompassing only one known gene, and therefore unlikely to be the cause of the phenotype. However, the role of other genetic factors, such as a recessive condition, could not be ruled out as a putative cause for the phenotype. On the other hand, the role played by a heavily detrimental familial situation on the development and outcome, and possibly leading or contributing to a mild intellectual disability, should be taken into account

The Spatial Structure of Sexual and Cytonuclear Polymorphism in the Gynodioecious Beta vulgaris ssp. maritima: I/ at a Local Scale

International audienceWe have analyzed the spatial distribution of the sex phenotypes and of mitochondrial, chloroplast, and nuclear markers within two gynodioecious populations of Beta vulgaris ssp. maritima. Within both populations , sexual phenotype variation is controlled mainly by the cytoplasmic genotype, although in one study population a joint polymorphism of cytonuclear factors is clearly involved. In spite of contrasts in the ecology (mainly due to different habitats), a clear common feature in both populations is the highly patchy distribution of cytoplasmic haplotypes, contrasting with the wide distribution of nuclear diversity. This high contrast between cytoplasmic vs. nuclear spatial structure may have important consequences for the maintenance of gynodioecy. It provides opportunities for differential selection since nuclear restorer alleles are expected to be selected for in the presence of their specific cytoplasmic male sterile (CMS) type, but to be neutral (or selected against if there is a cost of restoration) in the absence of their CMS type. Selective processes in such a cytonuclear landscape may explain the polymorphism we observed at restorer loci for two CMS types

Developmental expression and organisation of fibrinogen genes in the zebrafish

The zebrafish is a model organism for studying vertebrate development and many human diseases. Orthologues of the majority of human coagulation factors are present in zebrafish, including fibrinogen. As a first step towards using zebrafish to model human fibrinogen disorders, we cloned the zebrafish fibrinogen cDNAs and made in situ hybridisations and quantitative reverse transcription-polymerase chain reactions (qRT-PCR) to detect zebrafish fibrinogen mRNAs. Prior to liver development or blood flow we detected zebrafish fibrinogen expression in the embryonic yolk syncytial layer and then in the early cells of the developing liver. While human fibrinogen is encoded by a three-gene, 50 kilobase (kb) cluster on chromosome 4 ( FGB-FGA-FGG ), recent genome assemblies showed that the zebrafish fgg gene appears distanced from fga and fgb , which we confirmed by in situ hybridisation. The zebrafish fibrinogen Bβ and γ protein chains are conserved at over 50% of amino acid positions, compared to the human polypeptides. The zebrafish Aα chain is less conserved and its C-terminal region is nearly 200 amino acids shorter than human Aα. We generated transgenic zebrafish which express a green fluorescent protein reporter gene under the control of a 1.6 kb regulatory region from zebrafish fgg . Transgenic embryos showed strong fluorescence in the developing liver, mimicking endogenous fibrinogen expression. This regulatory sequence can now be used for overexpression of transgenes in zebrafish hepatocytes. Our study is a proof-of-concept step towards using zebrafish to model human disease linked to fibrinogen gene mutations

Characterization of an interstitial deletion 6q13-q14.1 in a female with mild mental retardation, language delay and minor dysmorphisms

Chromosomal imbalances, recognized as the major cause of mental retardation (MR), are often due to submicroscopic deletions or duplications not evidenced by conventional cytogenetic methods. Array-based comparative genomic hybridization (array-CGH) improves considerably the detection rate of submicroscopic chromosomal abnormalities and has proven to be an effective tool for detection of submicroscopic chromosome abnormalities in children with MR and/or multiple congenital defects. Observations of array-CGH deletions in defined chromosomal regions linked to a clinical phenotype will more and more allow to define genotype-phenotype correlations. We report here the case of a 10-year-old female with a de novo 7.8 Mb deletion in the 6q13-6q14.1 ascertained by array-CGH. The clinical features of this patient include psychomotor and language delay associated with minor dysmorphic features

A de novo 12q13.11 microdeletion in a patient with severe mental retardation, cleft palate, and high myopia

We report a de novo 12q13.11 deletion of 1.3 Mb in an 10-year-old dysmorphic girl with a multiple congenital anomalies/mental retardation (MCA/MR) syndrome consisting mainly of severe mental retardation, cleft palate, and high myopia. The deleted region encompasses 16 RefSeq genes. Among these, it is hypothesized that haploinsufficiency of AMIGO2 is potentially responsible for the mental retardation of this patient, and of COL2A1 for the cleft palate and high myopia

A recurrent 14q32.2 microdeletion mediated by expanded TGG repeats

Nearly all recurrent microdeletion/duplication syndromes described to date are characterized by the presence of flanking low copy repeats that act as substrates for non-allelic homologous recombination (NAHR) leading to the loss, gain or disruption of dosage sensitive genes. We describe an identical 1.11 Mb heterozygous deletion of 14q32.2 including the DLK1/GTL2 imprinted gene cluster in two unrelated patients. In both patients, the deleted chromosome 14 was of paternal origin, and consistent with this both exhibit clinical features compatible with uniparental disomy (UPD) (14)mat. Using a high-resolution oligonucleotide array, we mapped the breakpoints of this recurrent deletion to large flanking (TGG)(n) tandem repeats, each approximately 500 bp in size and sharing > or =88% homology. These expanded (TGG)(n) motifs share features with known fragile sites and are predicted to form strong guanine quadruplex secondary structures. We suggest that this recurrent deletion is mediated either by NAHR between the TGG repeats, or alternatively results from their inherent instability and/or strong secondary structure. Our results define a recurrent microdeletion of the 14q32.2 imprinted gene cluster mediated by flanking (TGG)(n) repeats, identifying a novel mechanism of recurrent genomic rearrangement. Our observation that expanded repeats can act as catalysts for genomic rearrangement extends the role of triplet repeats in human disease, raising the possibility that similar repeat structures may act as substrates for pathogenic rearrangements genome-wide

Generation of human induced pluripotent stem cell line UNIGEi003-A from skin fibroblasts of an apparently healthy male donor

Dermal fibroblasts isolated from an apparently healthy 50-year-old man were successfully transformed into induced pluripotent stem cells (iPSCs) by using the integration-free CytoTune-iPS Sendai Reprogramming method. The generated iPSC line has been expanded under feeder-free conditions and displayed all hallmarks of a standard pluripotent stem cell line such as a normal karyotype, expression of pluripotent factors and differentiation capacity into the three germ layers