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Biomedical subjects

J Frezal

Publications and source records attributed to J Frezal.

At least 19 recordsLinked to original sources
PubMed1999

Human genes involved in chromatin remodeling in transcription initiation, and associated diseases: An overview using the GENATLAS database.

Chromatin structure is inextricably linked to transcription regulation and differentiation. It consists of a multicomponent system, and impairments in such complex arrays may elicit dramatic biological effects and diseases. We present an overview of human genes involved in chromatin remodeling, which consist of the histone acetyltransferase/deacetylase system and the SWI/SNF-like complexes containing DNA-dependent ATPase activity. Special attention is given to the functional and physical interactions in which these components are involved, notably as transcriptional coactivators and/or corepressors of a large variety of genes. Linking seemingly distinct pathways allows integration of individual components into complex genetic and molecular processes and assessment of the underlying molecular bases of diseases. This was performed using GENATLAS (http://www.infobiogen.fr/), a gene database which compiles the information relevant to the mapping efforts from the published literature.

Chromatin↗
PubMed1997

Report on the Fifth International Workshop on Chromosome 9 held at Eynsham, Oxfordshire, UK, September 4-6, 1996.

The Fifth International workshop on chromosome 9 comprised a gathering of 36 scientists from seven countries and included a fairly even distribution of interests along chromosome 9 as well as a strong input from more global activities and from comparative mapping. At least eight groups had participated in the goal set at the previous workshop which was to improve the fine genetic mapping in different regions of chromosome 9 by meiotic breakpoint mapping in allocated regions and this has resulted in some greatly improved order information. Excellent computing facilities were available and all contributed maps were entered not only into SIGMA (and thence submitted to GDB) but also into a dedicated version of ACEDB which can be accessed on the Web in the form of one of 28 slices into which the chromosome has been arbitrarily divided. It was generally agreed that the amount of data is now overwhelming and that the integration and validation of all data is not only unrealistic in a short meeting but probably impossible until the whole chromosome has been sequenced and fully annotated. Sequence-ready contigs presented at the meeting totalled about 3 MB which is about one fiftieth of the estimated length. The single biggest barrier to integration of maps is the problem of non-standard nomenclature of loci. In the past 2 workshops efforts have been made to compare traditional 'consensus' maps made by human insight (still probably best for small specific regions) with those generated with some computer assistance (such as SIGMA) and those generated objectively by defined computer algorithms such as ldb. Since no single form of map or representation is entirely satisfactory for all purposes the maps reproduced in the published version of the report are confined to one of the genetic maps, in which Genethon and older markers have been incorporated, a Sigma map of the genes as symbols together with a listing of known 'disease' genes on chromosome 9, and a revised assessment of the mouse map together with a list of mouse loci predicted to be on human chromosome 9. One of the 28 ACEDB slices is also shown to illustrate strengths and weaknesses of this approach. Workshop files include not only all maps available at the time but also details of loci and details of the meiotic breakpoints in the CEPH families (http:/(/)www.gene.ucl.ac.uk/scw9db.shtml) .

Animals↗
PubMed1996

A metric map of humans: 23,500 loci in 850 bands.

High-resolution maps integrated with the enhanced location data base software (LDB+) give improved estimates of genetic parameters and reveal characteristics of cytogenetic bands. Chiasma interference is intermediate between Kosambi and Carter-Falconer levels, as in Drosophila and the mouse. The autosomal genetic map is 2832 and 4348 centimorgans in males and females, respectively. Telomeric T-bands are strikingly associated with male recombination and gene density. Position and centromeric heterochromatin have large effects, but nontelomeric R-bands are not significantly different from G-bands. Several possible reasons are discussed. These regularities validate the maps, despite their high resolution and inevitable local errors. No other approach has been demonstrated to integrate such a large number of loci, which are increasing at about 45% per year. The maps and the data and software from which they are constructed are available through the Internet (http:@cedar.genetics.soton.ac.uk/public_html). Successive versions of this location data base may also be accessed on CD-ROM.

Chromosome Banding↗
PubMed1995

Exclusion of the cone-specific alpha-subunit of the transducin gene in Stargardt's disease.

Stargardt's disease is an autosomal recessive infantile macular degeneration of unknown origin whose gene has been recently mapped to chromosome 1p21-p13 by linkage analysis in eight multiplex families. Since the cone-specific alpha-subunit of the transducin gene (GNAT2) has been mapped to chromosome 1p13, we tested GNAT2 as the disease-causing gene in our series. Using a novel intragenic polymorphism, we show here that GNAT2 is most probably located centromeric to the genetic interval encompassing the disease gene (D1S424-D1S236, location score = 3.54). In addition, single-strand conformation polymorphism and sequence analyses of the eight exons of the GNAT2 gene was performed in our probands. No evidence of a deleterious base substitution was observed in any affected individual. Taken together, these results support the exclusion of GNAT2 as the causal disease gene of Stargardt's disease. come. The pathogenesis is unknown and the treatment is limited to ultraviolet ray protection with dark glasses. Stargardt's disease has been recently mapped to chromosome 1p21-p13 in the genetic interval defined by loci D1S424 and D1S236. In addition, our previous study has suggested that Stargardt's disease is genetically homogeneous (Kaplan et al. 1993). With respect to the physical mapping of the proteins specific to the retinal pigmentary epithelium or to cones we noted that the cone-specific alpha-subunit of the transducin gene (GNAT2) has been mapped to chromosome 1p13 (Wilkie et al. 1992). The human GNAT2 is 9967 bp in length and consists of eight exons with seven introns (Morris and Fong 1993). In the present study, we examined this gene as the candidate gene in eighteen unrelated patients affected with Stargardt's disease.

Base Sequence↗
PubMed1994

Stargardt's disease is not allelic to the genes for neuronal ceroid lipofuscinoses.

Stargardt's disease is an autosomal recessive condition characterised by a rapid and bilateral loss of central vision at around 7 to 12 years, with typical changes in the macular and perimacular region. It is one of the most frequent causes of macular degeneration in childhood and accounts for 7% of all retinal dystrophies. Considering that inclusions of lipofuscin-like substances are observed in retinal pigmentary cells of patients with Stargardt's disease on the one hand, and that the early symptoms of neuronal ceroid lipofuscinosis (CLN3) are suggestive of Stargardt's disease on the other hand (age of loss of visual acuity, appearance of the fundus), we decided to test allelism of Stargardt's disease with the infantile (CLN1) and juvenile forms of neuronal ceroid lipofuscinosis (CLN3), which map to chromosomes 1p32 and 16p12-p11 respectively. Using highly informative microsatellite DNA markers in eight multiplex families, we were able to exclude Stargardt's disease from the vicinity of the CLN1 and CLN3 loci. These results strongly reject the hypothesis of allelism of Stargardt's disease with the neuronal forms of ceroid lipofuscinosis.

Alleles↗
PubMed1990

Mapping of acute (type I) spinal muscular atrophy to chromosome 5q12-q14. The French Spinal Muscular Atrophy Investigators.

Linkage analysis in twenty-five families with acute (type I) spinal muscular atrophy (SMA) showed that the mutant gene responsible for the disorder is tightly linked to the D5S39 locus. The mutation(s) causing the intermediate (type II) and juvenile chronic (type III) forms of SMA were also mapped to DNA marker D5S39 on chromosome 5 (5q12-q14). Thus, the three forms, which have been differentiated clinically on the basis of age of onset and clinical course, are most probably due to different mutations at a single locus on chromosome 5. Prenatal diagnosis of SMA type I will now be possible.

Acute Disease↗
PubMed1990

Exclusion of linkage between D3S47 (C17) and ADRPII gene in two large families of moderate autosomal dominant retinitis pigmentosa: evidence for genetic heterogeneity.

Autosomal dominant forms of retinitis pigmentosa appear among the most frequent types of retinal degenerations. Two clinical subtypes have been recognized, namely the early onset, severe form (type I) and the late onset, moderate form (type II). A linkage between the D3S47 probe (C17) with the gene of the type I has been recently demonstrated by Humphries et al., 1989. Here, two families with type II of the disease have been tested for possible allelism at the D3S47 locus. A negative lod-score was found with this probe and a linkage with this region could be excluded. These results support the hypothesis of a genetic heterogeneity in autosomal dominant forms of retinitis pigmentosa.

Genes, Dominant↗
PubMed1989

The anonymous PAS45 probe detects RFLPs in 13q31.

An anonymous DNA probe PAS45 was isolated. This probe detects an RFLP with two alleles 1 and 2 at the same locus, with the different restriction enzymes (Bg1II, EcoRI, HindIII, PstI, MspI, XbaI). The observed polymorphism is explained by a chromosome rearrangement involving these enzyme cleavage sites. The frequency of alleles 1 and 2 was 0.875 and 0.125, respectively, in a sample of 48 unrelated individuals in France. Codominant inheritance of alleles 1 and 2 was demonstrated in 13 families with 30 offspring. The PAS45 probe was localized on chromosome 13 by somatic cell hybrid analysis and on 13q31 by in situ hybridization. The rearrangement on 13q31 is present in one out of four healthy individuals in France.

Animals↗
PubMed1988

[Genetic counseling in ornithine carbamoyltransferase deficiency].

Ornithine transcarbamylase (OTC) deficiency is an inborn error of urea cycle metabolism, responsible for lethal hyperammonemia in males and for severe symptoms in at least 20% of heterozygous females. The authors provide here additional data on the informativity of the protein loading test (PLT) for the detection of heterozygotes. They show that the risk of being a carrier for the mother of an affected boy falls from 2/3 a priori to only 1/8 if her PLT is negative. The risk for the mother of heterozygote girl falls from 1/2 a priori to 1/16 if her PLT is negative.

Amino Acid Metabolism, Inborn Errors↗
PubMed1986

[Palmoplantar keratosis associated with keratitis: hereditary hypertyrosinemia treated by diet].

The authors report the cases of two unrelated children 16 and 5 years of age respectively, affected with hypertyrosinaemia type II. This condition is characterized by palmo-plantar hyperkeratosis associated with a herpetiform keratitis. The diagnosis is based on the finding of hypertyrosinaemia and hypertyrosyluria, and may be confirmed by their biopsy findings of a cytoplasmic tyrosine amino-transferase deficiency. It is a hereditary autosomal recessive disease. A low phenylalanine and tyrosine diet produced a spectacular improvement but the ocular complications could have been avoided by an earlier diagnosis.

Adolescent↗
PubMed1986

Panel of twenty-five independent man-rodent hybrids for human genetic marker mapping.

To increase the efficiency of the human gene mapping, a panel of 25 man-rodent hybrids was selected out of 200 independent man-rodent hybrids produced in our laboratory since 1969. The hybrid panel was selected in such a fashion as to allow the asignment of a human marker M by respecting the two following complementary criteria: correlation between M and a chromosome and exclusion of the other chromosomes. The panel characteristics allowing the use of these two criteria were presented and discussed. A first series of enzyme markers were analysed to test the validity of the hybrid panel for the human gene mapping. The different possibilities and limits of the hybrid panel were also discussed, especially for the assignment of markers with DNA probes.

Animals↗
PubMed1986

[The genetics of collagen diseases].

Heritable disorders of collagen include Ehler-Danlos syndromes (11 types are actually known), Larsen syndrome and osteogenesis imperfecta. Their clinical, genetic and biochemical features are reviewed. Marfan syndrome is closely related to heritable disorders of collagen.

Abnormalities, Multiple↗