PubMed Health⌕ Search

Biomedical subjects

J Chelly

Publications and source records attributed to J Chelly.

At least 73 records · Page 4Linked to original sources
PubMed1998

Inherited microdeletion in Xp21.3-22.1 involved in non-specific mental retardation.

X-linked mental retardation (XLMR) is a genetically and clinically heterogeneous common disorder. A cumulative frequency of about 1/600 male births was estimated by different authors, including the fragile X syndrome, which affects 1/4000 males. Given this very high cumulative frequency, identification of genes and molecular mechanisms involved in other XLMRs, represents a challenging task of considerable medical importance. In this report we describe clinical and molecular investigations in the family of a mentally retarded boy for whom a microdeletion in Xp21.3-22.1 was detected within the frame of a previously reported systematic search for deletion using STS-PCR screening. Thorough clinical investigation of the sibling showed that two affected brothers exhibit a moderate non-specific mental retardation without any additional neurological impairment, statural growth deficiency or characteristic dysmorphy. Molecular analysis revealed that the microdeletion observed in this family is an inherited defect which cosegregates with mental retardation as an X-linked recessive condition, since both non-deleted boys and transmitting mother are normal. These results and the inherited microdeletion detected within the same region associated with non-specific MR, reported by Raeymaekers et al., suggest that Xp21.3 MR locus is prone to deletions. Therefore, search for microdeletions in the eight families assigned by linkage analysis to this region might allow a better definition of the critical region and an identification of the gene involved in this X-linked mental retardation.

Child↗
PubMed1998

A gene for non-specific X-linked mental retardation (MRX55) is located in Xp11.

A new family with a non-specific X-linked mental retardation (MRX55) is described. An X-linked recessive inheritance is suggested by the segregation from two healthy transmitting females of moderate mental retardation in three males, without any specific clinical, radiological or biological features. Two point linkage analysis demonstrated significant linkage between the disorder and several markers in Xp11 (Zmax = 2.11, theta = 0); multipoint linkage analyses confirmed the significant linkage with a maximum lod score (Z = 2.11 at theta = 0, at DXS8012). Recombination events observed with the flanking markers DXS1068 and DXS1275 delineate a 34 centimorgan interval in the pericentromeric region. The interval of assignment pointed out in this family overlaps with several MRX loci previously reported in Xp11 which are reviewed here in.

Chromosome Mapping↗
PubMed1997

Gene for nonspecific X-linked mental retardation (MRX 47) is located in Xq22.3-q24.

We describe a large family with nonspecific X-linked mental retardation (MRX 47). An X-linked recessive transmission is suggested by the inheritance from the mothers in two generations of a moderate to severe form of mental retardation in six males, without any specific clinical findings. Two point linkage analysis demonstrated significant linkage between the disorder and two markers in Xq23 (Zmax = 3.75, theta = 0). Multipoint linkage analyses confirmed the significant linkage with a maximum lod score (Z = 3.96, theta = 0) at DXS1059. Recombination events observed with the flanking markers DXS1105 and DXS8067 delineate a 17 cM interval. This interval overlaps with several loci of XLMR disorders previously localized in Xq23-q24, which are reviewed herein.

Chromosome Mapping↗
PubMed1997

Dominant X linked subcortical laminar heterotopia and lissencephaly syndrome (XSCLH/LIS): evidence for the occurrence of mutation in males and mapping of a potential locus in Xq22.

X linked subcortical laminar heterotopia and lissencephaly syndrome (XSCLH/ LIS) is an intriguing disorder of cortical development, which causes classical lissencephaly with severe mental retardation and epilepsy in hemizygous males, and subcortical laminar heterotopia (SCLH) associated with milder mental retardation and epilepsy in heterozygous females. Here we report an exclusion mapping study carried out in three unrelated previously described families in which males are affected with lissencephaly and females with SCLH, using 38 microsatellite markers evenly distributed on the X chromosome. Most of the X chromosome was excluded and potential intervals of assignment in Xq22.3-q23 or in Xq27 are reported. Although the number of informative meioses did not allow a decision between these two loci, it is worth noting that the former interval is compatible with the mapping of a breakpoint involved in a de novo X;autosomal balanced translocation 46,XX,t(X;2)(q22;p25) previously described in a female with classical lissencephaly. In addition, haplotype inheritance in two families showed a grandpaternal origin of the mutation and suggested in one family the presence of mosaicism in germline cells of normal transmitting males.

Adult↗
PubMed1997

A gene for dominant nonspecific X-linked mental retardation is located in Xq28.

A large family (MRX48) with a nonspecific X-linked mental retardation condition is described. An X-linked semidominant inheritance is suggested by the segregation in three generations of a moderate to severe mental retardation in seven males and by a milder intellectual impairment in two females, without any specific clinical, radiological, or biological feature. Two-point linkage analysis demonstrated significant linkage between the disorder and several markers in Xq28 (maximum LOD score [Zmax] = 2.71 at recombination fraction [theta] = 0); multipoint linkage analyses confirmed the significant linkage with a Zmax of 3.3 at theta = 0, at DXS1684. A recombination event observed with the flanking marker DXS8011 delineates a locus between this marker and the telomere. The approximate length of this locus is 8-9 cM, corresponding to 5.5-6 Mb. In an attempt to explain the variable intellectual impairment in females, we examined X-chromosome inactivation in all females of the family. Inactivation patterns in lymphocytes were random or moderately skewed, and no correlation between the phenotypic status and a specific inactivation pattern was observed. The interval of assignment noted in this family overlaps with five MRX loci previously reported in Xq28.

Adult↗
PubMed1996

X-linked neurodegenerative syndrome with congenital ataxia, late-onset progressive myoclonic encephalopathy and selective macular degeneration, linked to Xp22.33-pter.

Linkage analysis was performed in a previously described family segregating for an X-linked progressive neurological disorder [Bertini et al., 1992]. In three generations, the disease was inherited from the mothers in seven affected males (Fig. 1). Five had severe congenital hypotonia and died during the first year of life. Two other boys (maternal cousins) were found to have severe congenital ataxia, late-onset progressive myoclonic encephalopathy, and selective macular degeneration; brain CT-scan showed moderate cerebellar vermis hypoplasia. Linkage analysis was carried out in 12 informative relatives using 35 microsatellite markers (Généthon) evenly distributed on the X chromosome. A multipoint analysis showed a significant linkage (Z > 2) between the disease and three markers in the Xp22.33 region: DYS403 (Z = 2.37, theta = 0) which maps in the pseudoautosomal region, DXS7099 (Z = 2.45, theta = 0), and DXS7100 (Z = 2.48, theta = 0). Further linkage analysis with more telomeric markers will refine the location of this severe X-linked encephalopathy.

Ataxia↗
PubMed1996

Identification by STS PCR screening of a microdeletion in Xp21.3-22.1 associated with non-specific mental retardation.

X-linked non-specific mental retardation (MRX) is a heterogeneous condition in which mental retardation (MR) appears to be the only consistent manifestation. The genetic and phenotypic heterogeneity exclude any possibility of pooling families and, therefore, of fine-mapping the related disease genes. In order to identify genomic critical regions involved in the MRX condition assigned to Xp21.3-22.1 region, we have implemented the PCR screening of non fragile X MR patients for the presence of deletions in this region. The amplification by PCR of 12 markers located between POLA and DXS704 using genomic DNA from 192 MR males led to the identification, in a 9 year old mentally retarded boy, of a microdeletion which extends from DXS1202 to DXS1065. None of the known genes, POLA, MAGE genes cluster, DAX1, GK and DMD, that map in the Xp21.3-22.1 region is affected by this deletion. This approach, which could easily be applied to several other MRX loci, allowed not only a confirmation of the presence of a potential locus in Xp21.3-22.1 involved in non-specific mental retardation, but also a better definition of the genomic critical region corresponding to this locus.

Child↗
PubMed1996

Analysis of alternative splicing patterns in the cystic fibrosis transmembrane conductance regulator gene using mRNA derived from lymphoblastoid cells of cystic fibrosis patients.

Using in vitro amplification of cDNA by the polymerase chain reaction, we analyzed alternatively spliced events of cystic fibrosis transmembrane conductance regulator gene in lymphoblastoid cells. Ten alternatively spliced transcripts were identified using analysis of 6 overlapping segments of amplified cDNA, 4 of which have not been described previously. These include transcripts lacking exon 16, 17b, 22 and a transcript resulting from the use of a cryptic acceptor and donor splice sites. Moreover, in 2 cystic fibrosis (CF) patients bearing nonsense mutations E60X or W1282X, we observed that nonsense mutations are associated with an alteration of splice site selection in vivo resulting in exon skipping of constitutive exons or in the use of cryptic splice sites. In addition, even though lymphoblastoid cells are not the relevant tissue to address the question of the relationship between clinical respiratory phenotype and genotype, our results concerning adult CF patients (delta F508/ delta F508) suggest that individual-specific RNA splicing patterns could influence the severity of the CF pulmonary disease. If this phenomenon of alternative splicing events proves to be significant in CF and to be a common feature of disease genes, the study of RNA splicing could become an important tool for the analysis of the genotype-phenotype relationship in many inherited disorders.

Adult↗
PubMed1996

Mutations and phenotype in isolated glycerol kinase deficiency.

We demonstrate that isolated glycerol kinase (GK) deficiency in three families results from mutation of the Xp21 GK gene. GK mutations were detected in four patients with widely differing phenotypes. Patient 1 had a splice-site mutation causing premature termination. His general health was good despite absent GK activity, indicating that isolated GK deficiency can be silent. Patient 2 had GK deficiency and a severe phenotype involving psychomotor retardation and growth delay, bone dysplasia, and seizures, similar to the severe phenotype of one of the first described cases of GK deficiency. His younger brother, patient 3, also had GK deficiency, but so far his development has been normal. GK exon 17 was deleted in both brothers, implicating additional factors in causation of the severe phenotype of patient 2. Patient 4 had both GK deficiency with mental retardation and a GK missense mutation (D440V). Possible explanations for the phenotypic variation of these four patients include ascertainment bias; metabolic or environmental stress as a precipitating factor in revealing GK-related changes, as has previously been described in juvenile GK deficiency; and interactions with functional polymorphisms in other genes that alter the effect of GK deficiency on normal development.

Abnormalities, Multiple↗
PubMed1995

Characterization of the exon structure of the Menkes disease gene using vectorette PCR.

The gene defective in Menkes disease, an X-linked recessive disturbance of copper metabolism, has been isolated and predicted to encode a copper-binding P-type ATPase. We determined the complete exon-intron structure of the Menkes disease gene, which spans about 150 kb of genomic DNA. The gene contains 23 exons, and the ATG start codon is in the second exon. All of the exon-intron boundaries were sequenced and conformed to the GT/AT rule, except for the 5' splice site of intron 9. A preliminary comparison demonstrated a striking similarity between the exon structures of the Menkes and Wilson disease genes, giving insight into their evolution.

Adenosine Triphosphatases↗
PubMed1995

Construction of a YAC contig spanning the Xq13.3 subband.

The loci involved in several X-linked mental retardation syndromes have been linked to the pericentromeric region of the X chromosome long arm (Xq12-q21). To isolate candidate genes for these diseases, we set up the construction of YAC contigs spanning this region. Two of these syndromes (the Juberg-Marsidi syndrome and the alpha-thalessemia mental retardation syndrome) have been recently linked, with high lod scores, to polymorphic probes previously assigned to Xq13.3. We therefore constructed a first YAC contig, encompassing this band, from DXS441 to PGK1. The physical map, deduced from the isolated clones, extends over 2.1 Mb of genomic DNA. Restriction analysis of the YAC contig allowed us to map precisely the loci previously assigned to that chromosomal region and to define their relative order. The validity of this physical map has been checked by comparing Sfi I digests of the YACs to genomic fragments obtained with the same enzyme. A cDNA selection approach, already performed with a previous partial contig, has been extended to cover the whole region.

Bacterial Proteins↗
PubMed1995

Assignment of the dystonia-parkinsonism syndrome locus, DYT3, to a small region within a 1.8-Mb YAC contig of Xq13.1.

A YAC contig was constructed of Xq13.1 in order to sublocalize the X-linked dystonia-parkinsonism (XDP) syndrome locus, DYT3. The contig spans a region of approximately 1.8 Mb and includes loci DXS453/DXS348/IL2R gamma/GJB1/CCG1/DXS559. For the construction of the contig, nine sequence-tagged sites and four short tandem repeat polymorphisms (STRPs) were isolated. The STRPs, designated as 4704#6 (DXS7113), 4704#7 (DXS7114), 67601 (DXS7117), and B4Pst (DXS7119) were assigned to a region flanked by DXS348 proximally and by DXS559 distally. Their order was DXS348/4704 #6/4704 #7/67601/B4Pst/DXS559. They were applied to the analysis of allelic association and of haplotypes in 47 not-obviously-related XDP patients and in 105 Filipino male controls. The same haplotype was found at loci 67601 (DXS7117) and B4Pst (DXS7119) in 42 of 47 patients. This percentage of common haplotypes decreased at the adjacent loci. The findings, together with the previous demonstration of DXS559 being the distal flanking marker of DYT3, assign the disease locus to a small region in Xq13.1 defined by loci 67601 (DXS7117) and B4Pst (DXS7119). The location of DYT3 was born out by the application of a newly developed likelihood method for the analysis of linkage disequilibrium.

Adult↗
PubMed1994

DXS106 and DXS559 flank the X-linked dystonia-parkinsonism syndrome locus (DYT3).

The locus (DYT3) underlying the X-linked dystonia-parkinsonism syndrome (XDP) was delineated within proximal Xq12-Xq13.1 by analysis of linkage, allelic association, and haplotypes. Short tandem repeat polymorphisms at loci DXS227, DXS559, DXS453, DXS106, DXS339, and DXS135 were studied. The occurrence of a recombination within a three-generation family established DXS559 as the distal flanking marker of DYT3. /phi/ and /delta/ values were determined as indicators of the degree of allelic association between DYT3 and the six marker loci. In addition, haplotype analysis was performed at the loci studied. The findings establish DXS106 as the proximal flanking marker of DYT3. Given an approximate distance between DXS106 and DXS559 of 3.0 Mb, isolation of DYT3 is now feasible by positional cloning techniques.

Alleles↗
PubMed1994

Analysis of Mnk, the murine homologue of the locus for Menkes disease, in normal and mottled (Mo) mice.

Menkes disease (MNK) lies immediately proximal to pphosphoglycerate kinase (PGK1) in Xq13 in human. Phenotypic similarities between MNK patients and murine mottled (Mo) mutants strongly suggest that both defects are caused by mutations at the same locus. Human MNK cDNA clones and a genomic subclone derived from a 40-kb YAC clone that includes Pgk1 have been used to position the murine homologue of Menkes disease (MNK, Mnk) immediately proximal to, and within 150-200 kb of, phosphoglycerate kinase (Pgk1) on the mouse X chromosome using interspecific backcross analysis and pulsed-field gel electrophoresis. A related autosomal locus has been mapped to mouse chromosome 18. RFLVs at Mnk between inbred strains of mice that show a strong association with the presence of the Mo phenotype have been detected. Hybridization of 4.1 kb of the 4.5-kb MNK coding sequence failed to reveal any deletions or alterations to restriction fragments containing exons of the Mnk locus in 9 Mo mutants. Furthermore, no genomic deletions or alterations > 20 kb were detected in 10 independently derived Mo mutants using pulsed-field gel electrophoresis. As no deletions or alterations at the Mnk gene were found, we suggest that any mutations in Mnk that cause the Mo phenotype are likely to be due to small changes at the nucleotide level and/or small deletions (< 20 kb) that lie outside the coding sequence.

Animals↗
PubMed1994

Isolation of the gene for McLeod syndrome that encodes a novel membrane transport protein.

McLeod syndrome is an X-linked multisystem disorder characterized by abnormalities in the neuromuscular and hematopoietic systems. We have assembled a cosmid contig of 360 kb that encompasses the McLeod gene locus. A 50 kb deletion was detected by screening DNA from patients with radiolabeled whole cosmids, and two transcription units were identified within this deletion. The mRNA expression pattern of one of them, designated as XK, correlates closely to the McLeod phenotype. XK encodes a novel protein with structural characteristics of prokaryotic and eukaryotic membrane transport proteins. Nucleotide sequence analysis of XK from two unrelated McLeod patients has identified point mutations at conserved splice donor and acceptor sites. These findings provide direct evidence that XK is responsible for McLeod syndrome.

Amino Acid Sequence↗