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S Kenwrick

Publications and source records attributed to S Kenwrick.

At least 55 records · Page 3Linked to original sources
PubMed1993

Genetic mapping of the X-linked dominant mutations striated (Str) and bare patches (Bpa) to a 600-kb region of the mouse X chromosome: implications for mapping human disorders in Xq28.

Striated (Str) and bare patches (Bpa) are X-irradiation-induced, X-linked dominant mouse mutations that are lethal prenatally in hemizygous males. To map the Str mutation, we generated a backcross involving Mus castaneus. Pedigree analysis of 193 affected female and normal male progeny from the cross places Str extremely close to DXMIT1 and favors a gene order of (Cf-9)-Ids-Gabra3-DXS1104h-(Str, DXMIT1)-F8a-DXPas8-DXBay6-DXMIT6 for the loci studied. This region of the mouse X Chromosome (Chr) is syntenic with proximal human Xq28. Based on the mode of inheritance and clinical phenotype, Str may be a homolog of human familial incontinentia pigmenti (IP2). Further refinement of our genetic mapping of bare patches positions that locus between DXS1104h and DXPas8 in the same region as Str, raising the possibility that Bpa and Str may be allelic or are due to mutations in overlapping contiguous genes.

Animals↗
PubMed1993

Refining the genetic location of the gene for X linked hydrocephalus within Xq28.

The most common inherited form of hydrocephalus, X linked hydrocephalus (HSAS), is characterised by mental retardation, adducted thumbs, and spastic paraplegia. Genetic analysis has mapped the locus for HSAS to subchromosomal band Xq28 within a region of approximately 2 megabases of DNA. In order to refine the location of the disease gene we have conducted genetic linkage analysis with Xq28 marker loci in four additional HSAS families. A lod score of 4.26 with polymorphic marker DXS52 (St14) confirms the linkage of HSAS to Xq28. Identification of a recombination event between the HSAS gene and Xq28 loci F8C and DXS605 (2-19) reduces the size of the interval likely to contain the disease locus to about 1.5 megabases, the distance between DXS605 and DXS52. The locus for neural cell adhesion molecule, L1CAM, maps within this interval and therefore represents a candidate gene for HSAS.

Adolescent↗
PubMed1992

Sequence of the human factor VIII-associated gene is conserved in mouse.

cDNA and genomic clones corresponding to the human factor VIII-associated gene (F8A) were isolated from mouse cDNA and F8A-enriched genomic libraries. The sequences of these clones revealed an intronless gene coding for 380 amino acids, with 85% identity to the predicted human sequence. The single murine gene copy is genetically linked to factor VIII, but appears to lie outside the factor VIII gene by physical mapping. Like the human gene, the mouse F8A gene is highly expressed in a wide variety of tissues. This evolutionary comparison has helped to clarify the derived amino acid sequence in the human and strongly supports the hypothesis that the F8A gene encodes a protein.

Amino Acid Sequence↗
PubMed1992

Evidence for a third transcript from the human factor VIII gene.

Intron 22 of the human factor VIII gene was recently found to contain a gene, associated with a CpG island, which is transcribed in the direction opposite to factor VIII. We now report that another transcript emanates from the island and is transcribed in the same direction as factor VIII. The divergent transcripts originate within 122 bases of each other. The newly identified 5' exon in intron 22 potentially codes for eight amino acids and is spliced to exons 23-26, with the factor VIII reading frame maintained. The protein encoded by this transcript would include the factor VIII C2 domain, responsible for phospholipid binding and essential for coagulant activity.

Amino Acid Sequence↗
PubMed1992

Aberrant splicing of neural cell adhesion molecule L1 mRNA in a family with X-linked hydrocephalus.

A locus for X-linked hydrocephalus (HSAS), which is characterized by mental retardation and enlarged brain ventricles, maps to the same subchromosomal region (Xq28) as the gene for neural cell adhesion molecule L1. We have found novel L1 mRNA species in cells from affected members of a HSAS family containing deletions and insertions produced by the utilization of alternative 3' splice sites. A point mutation at a potential branch point signal in an intron segregates with the disease and is likely to be responsible for the abnormal RNA processing. These results suggest that HSAS is a disorder of neuronal cell migration due to disruption of L1 protein function.

Base Sequence↗
PubMed1992

Isolation and sequence of two genes associated with a CpG island 5' of the factor VIII gene.

Many disease loci have been linked to the telomeric end of the long arm of the human X-chromosome, Xq28. We have isolated and sequenced cDNA sequences corresponding to two novel genes that map to Xq28. These genes, c6.1A and c6.1B, are transcribed in opposite directions from a CpG island that lies approximately 70 kilobases (kb) upstream (5') of the factor VIII locus. One of these genes, c6.1A, is highly conserved between species and expressed abundantly in many human and mouse tissues, whereas, c6.1B is moderately conserved and has a restricted tissue distribution of expression. The Xq28 gene c6.1A has an autosomal homologue that is transcriptionally inactive in B-cell lines. An open reading frame (ORF) predicting a peptide of 293 amino acids is observed for c6.1A but c6.1B does not possess a single long ORF. No striking homologies to existing genes could be found for either of the two new loci. Expressed sequences that are physically close to the factor VIII gene are candidates for disease loci that map to this region of Xq28. The relevance of these genes to disease loci was investigated using DNA and RNA from hemophilia A patients bearing deletions that extend in a 5' direction away from factor VIII. The results imply that neither of these genes are primarily responsible for the development Xq28-linked diseases. However, c6.1A and c6.1B define a region of Xq28 that is deleted in two brothers that suffer from mental handicap and dysmorphism as well as hemophilia A. Thus, this region is likely to contain loci that are important for physical and mental development.

Amino Acid Sequence↗
PubMed1991

Mapping of human chromosome Xq28 by two-color fluorescence in situ hybridization of DNA sequences to interphase cell nuclei.

We have used the proximity of probe hybridization sites in interphase chromatin to derive the order of DNA sequences in a 2-3-Mbp region of human chromosome Xq28. The map generated bridges the results of genetic and pulsed-field gel electrophoresis mapping to produce a more complete map of Xq28 than possible with either of these other techniques alone. Two-color fluorescence in situ hybridization (FISH) was used to detect the positions of two or more probes in G1 male interphase nuclei. We show that cosmids that are 50 kbp to 2-3 Mbp apart can be ordered rapidly with two alternative approaches: (1) by comparing the average measured distance between two probes and (2) simply by scoring the order of red and green fluorescent dots after detection of three or more probes with two fluorochromes. The validity of these approaches is demonstrated using five cosmids from a region spanning approximately 800 kbp that includes the factor VIII (F8), glucose-6-phosphate dehydrogenase (G6PD), and color-vision pigment (CV) genes. The cosmid map derived from interphase mapping is consistent with the map determined by restriction-fragment analysis. The two interphase mapping approaches were then used (1) to orient the F8/CV cluster relative to two markers, c1A1 and st14c, which we show by metaphase mapping to be proximal to the F8/CV cluster, (2) to position st14c (DXS52) between c1A1 and F8, and (3) to orient the CV gene cluster relative to G6PD by using two CV-flanking cosmids, 18b41 and fr7. The probe order in Xq28 derived from interphase proximity is cen-c1A1-st14c-5'F8 (p624-p542-p625)-G6PD-18b41-3' green-green-red-fr7-tel. We also show that, to determine their order by using metaphase chromosomes, sequences must be at least 1 Mbp apart, an order of magnitude greater than required in interphase chromatin. The data show that FISH mapping is a simple way to order sequences separated by greater than or equal to 50 kbp for the construction of long-range maps of mammalian genomes.

Chromosome Mapping↗
PubMed1990

A transcribed gene in an intron of the human factor VIII gene.

We have identified a CpG island contained within the largest factor VIII intron. This island is associated with a 1.8-kb transcript and, unlike factor VIII, is produced abundantly in a wide variety of cell types. The nested gene is oriented in a direction opposite to that of factor VIII and contains no intervening sequences. A cDNA of 1739 bases was isolated from a human liver library and found to have a GC-rich, long open reading frame. Two computer-assisted methods (Fickett TESTCODE and Staden-McLachlan codon usage) predict that the gene codes for a protein. Two other copies of this gene are located within 1.1 Mb of the factor VIII gene. Northern blot analysis of RNA isolated from hemophilia patients deleted for factor VIII sequences has shown that both the intron gene and at least one other copy of the gene are transcribed. A homologous, transcribed sequence is also present in mice.

Amino Acid Sequence↗
PubMed1989

A contiguous, 3-Mb physical map of Xq28 extending from the colorblindness locus to DXS15.

Using pulsed-field gel electrophoresis (PFGE), we have generated a 3-megabase (Mb) physical map of Xq28, a region of the human genome known to contain many disease loci. We have determined the location of the genes for protan/deutan colorblindness (R/GCP), factor VIII (F8), glucose-6-phosphate dehydrogenase (G6PD), and a series of RFLPs and have derived the following order for this region: R/GCP-GdX-G6PD-F8-DXS115-DXS33-DXS134-D XS15. Using newly isolated probes, we have also established the direction of transcription of F8 within the map and have localized CpG islands flanking this gene.

Blotting, Southern↗
PubMed1987

Mapping of DNA markers close to the fragile site on the human X chromosome at Xq27.3.

We report the identification of a new RFLP detected by the DNA probe MN12, which is linked to both the fragile site on the X chromosome at Xq27.3 and the highly polymorphic locus detected by St14 (DXS52). In situ mapping confirms the localisation of MN12 distal to the fragile site. A detailed physical analysis of this region of the X chromosome using pulsed-field gel electrophoresis has shown that MN12, St14 and DX13 (DXS15) are physically linked within a region of 470kb. A long range restriction map around the MN12 locus reveals at least two candidate HTF islands, suggesting the existence of expressed sequences in this region.

Base Sequence↗
PubMed1987

Molecular analysis of the Duchenne muscular dystrophy region using pulsed field gel electrophoresis.

Genetic and molecular studies show that the Duchenne muscular dystrophy (DMD) locus at Xp21 is large and complex. We have analyzed this region using pulsed field gel electrophoresis (PFGE) and have determined physical distances between Xp21 probes. The sum of the sizes of the Sfil restriction fragments detected by these probes is greater than 4000 kb. The deletion endpoints in two DMD patients were detected by observing changes in these restriction fragments. In addition, the Xp21 breakpoint for the X;1 translocation in an affected female was mapped. These results demonstrate the applicability of PFGE for analysis of Xp21, and should facilitate the mapping of other translocations and deletions in this region, some of which lead to glycerol kinase deficiency and adrenal hypoplasia as well as DMD.

Chromosome Deletion↗
PubMed1987

Chromosome-specific alpha satellite DNA from human chromosome 1: hierarchical structure and genomic organization of a polymorphic domain spanning several hundred kilobase pairs of centromeric DNA.

The human alpha satellite repetitive DNA family is organized as distinct chromosome-specific subsets localized to the centromeric region of each chromosome. Here, we report he isolation and characterization of cloned repeat units which define a hierarchical subset of alpha satellite on human chromosome 1. This subset is characterized by a 1.9-kb higher-order repeat unit which consists of 11 tandem approximately 171-bp alpha satellite monomer repeat units. The higher-order repeat unit is itself tandemly repeated, present in at least 100 copies at the centromeric region of chromosome 1. Using pulsed-field gel electrophoresis we estimate the total array length of these tandem sequences at the centromere of chromosome 1 to be several hundred kilobase pairs. Under conditions of high stringency, the higher-order repeat probe hybridizes specifically to chromosome 1 and can be used to detect several associated restriction fragment length DNA polymorphisms. As such, this probe may be useful for molecular and genetic analyses of the centromeric region of human chromosome 1.

Chromosome Mapping↗
PubMed1986

Linkage studies of X-linked recessive spastic paraplegia using DNA probes.

A family with six males affected by X-linked spastic paraplegia (McKusick No. 31290) is described. The disease was accompanied by mental retardation in all patients (severe in four cases with IQ of 40) and by absence of extensor pollicis longus (in four cases). The following X chromosome DNA probes were used in linkage studies: 782, RC8, 99-6, 754, OTC, L128, pDP34, p43-15, DX13, and St14. The mutation is closely linked to the loci DX13 (DXS15) and St14 (DXS52) (no recombinants in 11 meioses) and therefore localised to the telomeric region of the long arm of the human X chromosome.

Adolescent↗
PubMed1981

Tumour cells in metastatic deposits with altered sensitivity to natural killer cells.

If natural killer (NK) cells play a role in immunosurveillance it might by expected that, during the metastatic process, selection would occur for tumour cells with reduced NK sensitivity. This hypothesis was tested in the rat by measuring the NK sensitivity of cells freshly isolated from metastases of syngeneic transplanted spontaneous mammary carcinomas. Lysis was measured in a 6-h chromium release assay using normal syngeneic spleen cells as effectors. Our studies led to the following conclusions. (1) Metastases developing at certain tissue sites (draining lymph node and lung, but not pericardium) were frequently composed of tumour cells with markedly reduced sensitivity to NK cells. (2) This resistance could generally be detected only if freshly isolated tumour cell population were studied; after a few days in culture, resistant metastasis-derived tumour cells usually regained normal NK sensitivity. (3) Resistance to NK cells was not always due to the loss of NK target structures; it could also result from an innate resistance to the NK lytic mechanism. (4) The tissue distribution of NK-resistant metastases suggested that if NK cells exerted an immunoselective pressure they did so at the tissue site rather than in the primary tumour or in the bloodstream.

Adenocarcinoma↗