PubMed Health⌕ Search

Biomedical subjects

G Gyapay

Publications and source records attributed to G Gyapay.

At least 37 records · Page 2Linked to original sources
PubMed1997

Identification and chromosomal localization of human genes containing CAG/CTG repeats expressed in testis and brain.

Human genes containing triplet repeats have been demonstrated to be involved in several neurodegenerative diseases by expansion of the repeat in succeeding generations. To identify novel genes involved in such pathologies, we have isolated transcripts containing (CAG/CTG)n repeats using two approaches. First, we screened 4 x 10(6) clones representing 10 copies of a human testis cDNA library using a (CAG)14 oligonucleotide probe. Among the 910 clones identified, the 243 clones with the strongest hybridization signal were sequenced partially from 3' or 5' ends. This provided us with 251 partial sequences that grouped into clusters corresponding to 39 genes, of which 19 represent unknown species. Second, we selected 203 additional ESTs containing (CAG/CTG)n repeats representing 121 clusters from the IMAGE consortium infant brain cDNA library. From these two series of sequences, we have localized 95 genes on human chromosomes using a panel of whole genome radiation hybrid (Genebridge 4). These genes are located on all of the chromosomes except for chromosome X, the highest density being observed on chromosome 19.

Brain↗
PubMed1996

A gene map of the human genome.

The human genome is thought to harbor 50,000 to 100,000 genes, of which about half have been sampled to date in the form of expressed sequence tags. An international consortium was organized to develop and map gene-based sequence tagged site markers on a set of two radiation hybrid panels and a yeast artificial chromosome library. More than 16,000 human genes have been mapped relative to a framework map that contains about 1000 polymorphic genetic markers. The gene map unifies the existing genetic and physical maps with the nucleotide and protein sequence databases in a fashion that should speed the discovery of genes underlying inherited human disease. The integrated resource is available through a site on the World Wide Web at http://www.ncbi.nlm.nih.gov/SCIENCE96/.

Amino Acid Sequence↗
PubMed1996

Low-molecular-weight, calcium-dependent phospholipase A2 genes are linked and map to homologous chromosome regions in mouse and human.

The Group IIA phospholipase gene (PLA2G2A) protein coding regions exhibit significant homology with recently described Group IIC (PLA2G2C) and Group V (PLA2GV) genes. All three genes are present in many mammalian species and are expressed in a tissue-specific pattern. Here, we demonstrate in human that they are tightly linked and map to chromosome 1p34-p36.1. We also show that the homologous mouse loci are tightly linked (no observed recombination) on the distal part of chromosome 4, a region exhibiting synteny with human 1p34-p36. Unlike its rodent counterpart, human PLA2G2C appears to be a nonfunctional pseudogene.

Animals↗
PubMed1996

A comprehensive genetic map of the human genome based on 5,264 microsatellites.

The great increase in successful linkage studies in a number of higher eukaryotes during recent years has essentially resulted from major improvements in reference genetic linkage maps, which at present consist of short tandem repeat polymorphisms of simple sequences or microsatellites. We report here the last version of the Généthon human linkage map. This map consists of 5,264 short tandem (AC/TG)n repeat polymorphisms with a mean heterozygosity of 70%. The map spans a sex-averaged genetic distance of 3,699 cM and comprises 2,335 positions, of which 2,032 could be ordered with an odds ratio of at least 1,000:1 against alternative orders. The average interval size is 1.6 cM; 59% of the map is covered by intervals of 2 cM at most and 1% remains in intervals above 10 cM.

Algorithms↗
PubMed1996

Genotyping Procedures in Linkage Mapping

Genotyping methods based on nonradioactive detection of PCR products and suitable for large-scale mapping projects are described. Two alternative techniques are proposed for the genotyping of polymorphic short tandem repeats or microsatellite markers. The first is designed for investigators who do not have access to automatic sequencing machines. This technique uses multiplex analysis of PCR products that are separated on sequencing gels, transferred to nylon membranes, and detected by hybridization with nonradioactive probes. The second technique uses automatic sequencing machines for the detection of fluorescently labeled PCR products. Another method describes the analysis of nonpolymorphic markers in whole-genome radiation hybrids. This method uses separation and detection of PCR products on agarose gels.

Journal Article↗
PubMed1996

Regional assignment of human ESTs by whole-genome radiation hybrid mapping.

The UK HGMP Resource Centre's collection of human partial cDNA sequences (ESTs) have been examined for suitability for mapping by PCR on a panel of somatic cell hybrids. The chromosomal assignments of 92 ESTs were determined with a monochromosomal hybrid panel, and a subset of 45 were linked to genetic markers with a panel of whole-genome radiation hybrids (WG-RHs). These results demonstrate the potential of WG-RHs to construct a transcript map of the human genome.

Base Sequence↗
PubMed1996

Human desmin gene: cDNA sequence, regional localization and exclusion of the locus in a familial desmin-related myopathy.

Desmin is a muscle-specific intermediate filament that is encoded by a gene assigned to human chromosome 2q35. Desmin-related myopathies are inherited disorders characterized by an intrasarcoplasmic accumulation of desmin. Recently, the knockout of the desmin gene was shown to generate a myopathic syndrome in transgenic mice, suggesting that functional abnormality of desmin may generate similar clinical symptoms in mouse and human. To determine the potential role of the desmin gene in a well-defined desmin-related myopathy (autosomal dominant form of Fardeau), human desmin cDNAs obtained from affected and unaffected individuals were cloned, sequenced and compared. No obvious mutation was detected. A BssHII restriction fragment length polymorphism (RFLP) was identified in exon 6 of the desmin gene. This RFLP was associated with a previously identified EcoRV RFLP in exon 4 to generate a tetra-allelic system, which was tested for linkage to the desmin-related myopathy in three families. The human desmin gene was localized within an 11-cM interval on chromosome 2q using a panel of radiation hybrids. This 11-cM region was clearly excluded by linkage analysis in the three desmin-related myopathy families using a set of highly polymorphic microsatellite markers. These results suggest that the desmin gene is not primarily involved in this disease.

Alternative Splicing↗
PubMed1996

A complete genomic screen for multiple sclerosis underscores a role for the major histocompatability complex. The Multiple Sclerosis Genetics Group.

Multiple sclerosis (MS), an inflammatory autoimmune demyelinating disorder of the central nervous system, is the most common cause of acquired neurological dysfunction arising in the second to fourth decades of life. A genetic component to MS is indicated by an increased relative risk of 20-40 to siblings compared to the general population (lambda s), and an increased concordance rate in monozygotic compared to dizygotic twins. Association and/or linkage studies to candidate genes have produced many reports of significant genetic effects including those for the major histocompatability complex (MHC; particularly the HLA-DR2 allele), immunoglobulin heavy chain (IgH), T-cell receptor (TCR) and myelin basic protein (MBP) loci. With the exception of the MHC, however, these results have been difficult to replicate and/or apply beyond isolated populations. We have therefore conducted a two-stage, multi-analytical genomic screen to identify genomic regions potentially harbouring MS susceptibility genes. We genotyped 443 markers and 19 such regions were identified. These included the MHC region on 6p, the only region with a consistently reported genetic effect. However, no single locus generated overwhelming evidence of linkage. Our results suggest that a multifactorial aetiology, including both environmental and multiple genetic factors of moderate effect, is more likely than an aetiology consisting of simple mendelian disease gene(s).

Chromosome Mapping↗
PubMed1996

A radiation hybrid map of the human genome.

We have developed a panel of whole-genome radiation hybrids by fusing irradiated diploid human fibroblasts with recipient hamster cells. This panel of 168 cell lines has been typed with microsatellite markers of known genetic location. Of 711 AFM genetic markers 404 were selected to construct a robust framework map that spans all the autosomes and the X chromosome. To demonstrate the utility of the panel, 374 expressed sequence tags (ESTs) previously assigned to chromosomes 1, 2, 14 and 16 were localized on this map. All of these ESTs could be positioned by pairwise linkage to one of the framework markers with a LOD score of greater than 8. The whole genome radiation hybrid panel described here has been used as the starting material for the Genebridge4 panel that is being made widely available for genome mapping projects.

Animals↗
PubMed1995

An STS-based map of the human genome.

A physical map has been constructed of the human genome containing 15,086 sequence-tagged sites (STSs), with an average spacing of 199 kilobases. The project involved assembly of a radiation hybrid map of the human genome containing 6193 loci and incorporated a genetic linkage map of the human genome containing 5264 loci. This information was combined with the results of STS-content screening of 10,850 loci against a yeast artificial chromosome library to produce an integrated map, anchored by the radiation hybrid and genetic maps. The map provides radiation hybrid coverage of 99 percent and physical coverage of 94 percent of the human genome. The map also represents an early step in an international project to generate a transcript map of the human genome, with more than 3235 expressed sequences localized. The STSs in the map provide a scaffold for initiating large-scale sequencing of the human genome.

Animals↗
PubMed1995

Imprinted chromosomal regions of the human genome display sex-specific meiotic recombination frequencies.

BACKGROUND: Meiotic recombination events do not occur randomly along a chromosome, but appear to be restricted to specific regions. In addition, some regions in the genome undergo recombination more frequently in the germ cells of one sex than the other. Genomic imprinting, the process by which the two parental alleles of a gene are differentially marked, is another genetic phenomenon associated with inheritance from only one parent or the other. The mechanisms that control meiotic recombination and genomic imprinting are unknown, but both phenomena necessarily depend on the presence of some DNA signal sequences and/or on the structure of the surrounding chromatin domain. RESULTS: In the present study, we compared the frequencies of sex-specific recombination events in three chromosomal regions of the human genome that contain clustered imprinted genes. Alignment of the genetic and physical maps of the ZNF127-SNRPN-IPW-PAR-5-PAR-1 region on chromosome 15q11-q13 (associated with Prader-Willi and Angelman syndromes) and the IGF2-H19 region on chromosome 11p15.5 (associated with Beckwith-Wiedemann syndrome) shows that both regions recombine with very high frequency during male meiosis, and with very low frequency during female meiosis. A third region around the WT-1 gene on chromosome 11p13 also recombines with higher frequency during male meiosis. CONCLUSIONS: The results show that the two best-known imprinted regions in the human genome are characterized by significant differences in recombination frequency during male and female meioses. A third, less well-characterized, imprinted region shows a similar sex-specific bias. On the basis of these observations, we propose a model suggesting that the region-specific differential accessibility of DNA that leads to differential recombination rates during male and female meioses also leads to the male- and female-specific modification of the signal sequences that control genomic imprinting.

Base Sequence↗
PubMed1995

Characterization of regions of chromosomes 12 and 16 involved in nephroblastoma tumorigenesis.

There are at least three loci involved in Wilms' tumor (WT) tumorigenesis: WT1 in 11p13, WT2 in 11p15.5, and WT3, as yet unmapped. A compilation of cytogenetic data published for 107 WT revealed that deletion of chromosome 16 and duplication of chromosome 12 occur as frequently as the well-documented 11p deletions. Allelic imbalance for chromosomes 16 and 12 was investigated in a series of 28 WT. By use of a large panel of restriction fragment length polymorphisms and (CA)n probes, we demonstrated loss of heterozygosity (LOH) for 16q in seven (25%) of the tumors. The whole length of 16q was involved in six of the tumors. Moreover, consistent with a previous report of 16q13 LOH in a sporadic WT and a constitutional breakpoint with a Beckwith-Wiedemann patient, we map a region of particular interest to between D16S308 and D16S320. The assumption that 16q LOH may be an early event was based on: 1) the detection of 16q LOH in one case of nephroblastomatosis; 2) the presence of a complete (clonal) 16q LOH in a tumor with partial (mosaic) 11p LOH; and 3) 16q LOH as the sole abnormality in one WT. By quantification of chromosome 12 allelic imbalance, we detected duplication in 18% of the total series and in 25% of the sporadic unilateral cases. The common region extended from the centromere to D12S7 in 12q21.1-q23. We also suggest that the various pathogenetically important loci are not equally involved in the different forms of WT and that their sequential involvement may differ.

Aneuploidy↗
PubMed1995

Localization of Refsum disease with increased pipecolic acidaemia to chromosome 10p by homozygosity mapping and carrier testing in a single nuclear family.

Adult Refsum disease (ARD) is a rare autosomal recessive neurologic disorder associated with the accumulation in blood and tissues of phytanic acid, a natural compound of exogenous origin whose catabolism is impaired in patients. We present here genome wide linkage analysis of an atypical Refsum disease family where L-pipecolic acid level in blood was also increased, suggesting that the patients suffer from a new peroxisomal disorder intermediate between ARD and Infantile Refsum Disease (IRD, a peroxisomal deficiency disease). We were able to demonstrate significant linkage (lod score = 3.6) between Refsum Disease with increased Pipecolic Acidaemia (RDPA) and the interval defined by D10S249 and D10S466 on 10p in this single consanguineous family by combining lod score values obtained from analysis of the multiple affected sibs, haplotype homozygosity and from discrimination between healthy carriers and non carriers based on phytanate oxidase measurements. This illustrates the power of homozygosity mapping with a dense map of microsatellite markers. A similar strategy will allow testing for homogeneity/heterogeneity between RDPA and ARD or the rare complementation groups of IRD.

Cells, Cultured↗
PubMed1995

The Friedreich ataxia critical region spans a 150-kb interval on chromosome 9q13.

By analysis of crossovers in key recombinant families and by homozygosity analysis of inbred families, the Friedreich ataxia (FRDA) locus was localized in a 300-kb interval between the X104 gene and the microsatellite marker FR8 (D9S888). By homology searches of the sequence databases, we identified X104 as the human tight junction protein ZO-2 gene. We generated a large-scale physical map of the FRDA region by pulsed-field gel electrophoresis analysis of genomic DNA and of three YAC clones derived from different libraries, and we constructed an uninterrupted cosmid contig spanning the FRDA locus. The cAMP-dependent protein kinase gamma-catalytic subunit gene was identified within the critical FRDA interval, but it was excluded as candidate because of its biological properties and because of lack of mutations in FRDA patients. Six new polymorphic markers were isolated between FR2 (D9S886) and FR8 (D9S888), which were used for homozygosity analysis in a family in which parents of an affected child are distantly related. An ancient recombination involving the centromeric FRDA flanking markers had been previously demonstrated in this family. Homozygosity analysis indicated that the FRDA gene is localized in the telomeric 150 kb of the FR2-FR8 interval.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Ataxia with vitamin E deficiency: refinement of genetic localization and analysis of linkage disequilibrium by using new markers in 14 families.

Ataxia with vitamin E deficiency (AVED) is an autosomal recessive disease characterized clinically by neurological symptoms with often striking resemblance to those of Friedreich ataxia. This disorder has been reported previously as familial isolated vitamin E deficiency. We have mapped recently the AVED locus to a 5-cM confidence interval on chromosome 8q by homozygosity mapping in six Mediterranean families. We have now analyzed six new and two previously described families and demonstrate genetic homogeneity despite important clinical variability and wide geographic origins. Analysis of nine new tightly linked microsatellite markers, including four characterized in this study, revealed a predominant but not unique mutation in northern African populations, where this condition is more frequent. Haplotype analysis but also classical recombinations allowed us to refine the AVED position to a 1-cM interval. A YAC contig over this interval was constructed from marker STSs and YAC fingerprint data, in order to facilitate the search of the AVED gene.

Africa, Northern↗
PubMed1995

Readjusting the localization of merosin (laminin alpha 2-chain) deficient congenital muscular dystrophy locus on chromosome 6q2.

The laminin alpha 2-chain gene mutations (LAMA2) are responsible for about 50% of the cases of classical congenital muscular dystrophy. These patients form a clinically homogenous group presenting merosin (laminin alpha 2-chain) deficiency in muscle biopsies. The LAMA2 gene has been previously localized on 6q22-23 and the disease locus mapped in a 16 cM interval in 6q2 by homozygosity mapping. In the present report we establish, by haplotyping additional microsatellites markers in 18 consanguineous families, that LAMA2 gene is more centromeric than previously thought: between the flanking markers, D6S407 and D6S1705, distant of 3 cM. In this interval the microsatellite D6S1620 is homozygous for all the patients. The localization of LAMA2 gene was confirmed by radiation hybrid mapping. The 3 new highly informative markers can be very useful for prenatal diagnosis.

Chromosome Mapping↗