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J Gitschier

Publications and source records attributed to J Gitschier.

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

Isolation of a candidate gene for Menkes disease and evidence that it encodes a copper-transporting ATPase.

Menkes disease is an X-linked disorder of copper transport characterized by progressive neurological degeneration and death in early childhood. We have isolated a candidate gene (Mc1) for Menkes disease and find qualitative or quantitative abnormalities in the mRNA in sixteen of twenty-one Menkes patients. Four patients lacking Mc1RNA showed rearrangements of the Menkes gene. The gene codes for a 1,500 amino acid protein, predicted to be a P-type cation-transporting ATPase. The gene product is most similar to a bacterial copper-transporting ATPase and additionally contains six putative metal-binding motifs at the N-terminus. The gene is transcribed in all cell types tested except liver, consistent with the expression of the Menkes defect.

Adenosine Triphosphatases↗
PubMed1993

Inversions disrupting the factor VIII gene are a common cause of severe haemophilia A.

Mutations in the factor VIII gene have been discovered for barely more than half of the examined cases of severe haemophilia A. To account for the unidentified mutations, we propose a model based on the possibility of recombination between homologous sequences located in intron 22 and upstream of the factor VIII gene. Such a recombination would lead to an inversion of all intervening DNA and a disruption of the gene. We present evidence to support this model and describe a Southern blot assay that detects the inversion. These findings should be valuable for genetic prediction of haemophilia A in approximately 45% of families with severe disease.

Base Sequence↗
PubMed1992

Amino acid substitutions in conserved domains of factor VIII and related proteins: study of patients with mild and moderately severe hemophilia A.

Mutations leading to hemophilia A by substitution of amino acids in coagulation factor VIII may provide important clues to the structure and function of this large and enigmatic protein. To efficiently find missense mutations, hemophiliacs with mild and moderately severe forms of the disease were surveyed. DNA samples from affected individuals were assayed for mutations by denaturing gradient gel electrophoresis following DNA amplification of target regions, which included all coding regions except for that of the dispensable B domain. Missense mutations were observed in 20 of the 34 patients examined, with identical mutations found in five pairs of patients. All mutations were found in the repetitive A and C domains. By aligning these domains in factor VIII with homologous domains in factor V, ceruloplasmin, and the mouse milk fat globule membrane protein, it was determined that most mutations change amino acids in areas of strong sequence conservation. Three additional mutations were detected, including a point mutation in an intron, a stop codon mutation, and a silent base change. Ten of the 18 different mutations discovered in this patient population are reported here for the first time.

Amino Acid Sequence↗
PubMed1992

Extension of the physical map in the region of the mouse X chromosome homologous to human Xq28 and identification of an exception to conserved linkage.

We have extended our pulsed-field gel map of the region of the mouse X chromosome homologous to human Xq28 to include the loci Gdx (DXS254Eh), P3 (DXS253Eh), G6pd, Cf-8, and F8a. Gdx, P3, and G6pd are demonstrated to be physically linked to the X-linked visual pigment locus (Rsvp) within a maximal distance of 340 kb, while G6pd and Cf-8 are approximately 900 kb apart. These studies favor a gene order of cen-Rsvp-Gdx-P3-G6pd-(Cf-8)-tel and extend the physical map of this region to 5 million bp. In conjunction with previous physical mapping studies in both mouse and human, the results suggest conserved linkage for loci in this region of the mouse X chromosome and human Xq28. However, employing pulsed-field gel electrophoresis and genetic pedigree analysis of interspecific backcross progeny, we have found close linkage of a clone encoding a mouse homolog for human factor VIII-associated gene A (F8A) to DXPas8, thus revealing the first exception to conserved gene order between murine and human loci in the region.

Animals↗
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

Mutations in the V2 vasopressin receptor gene are associated with X-linked nephrogenic diabetes insipidus.

X-linked nephrogenic diabetes insipidus (NDI) is a rare disorder in which the kidney is insensitive to the antidiuretic hormone, vasopressin. It has been proposed that the kidney-specific V2 vasopressin receptor, a G protein-coupled receptor, is defective in this disorder as both the disease and the receptor map to Xq28. We report six unique mutations in the V2 receptor gene of five unrelated NDI patients, with one patient having two mutations. The most severely affected patient has a nonsense mutation which would terminate the protein in transmembrane domain III. Other mutations include three missense mutations, a frameshift and one small in-frame deletion. These results represent one of the first examples of recessive mutations affecting a G protein-coupled receptor.

Amino Acid Sequence↗
PubMed1992

The gene encoding the palmitoylated erythrocyte membrane protein, p55, originates at the CpG island 3' to the factor VIII gene.

A CpG island 30 kb 3' to the human factor VIII gene in Xq28 is associated with a 2-kb transcript. This gene encodes a previously described palmitoylated membrane protein, p55, containing a src homology motif, SH3. Although originally described in reticulocytes, the transcript is expressed in a wide variety of human tissues. The gene is also present in the mouse and expressed in all mouse tissues examined. No known factor VIII gene deletions extend into the p55 gene. Since the function of the p55 protein is not known, the p55 gene is formally a candidate for any of the 19 or more disease genes that have not been isolated but are closely linked genetically to the factor VIII gene.

Amino Acid 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

Haemophilia A: database of nucleotide substitutions, deletions, insertions and rearrangements of the factor VIII gene.

Mutations at the factor VIII gene locus causing Haemophilia A have now been identified in many patients from many ethnic groups. Earlier studies used biased methods which detected repetitive mutations at a few CG dinucleotides. More recently rapid gene scanning methods have uncovered an extreme diversity of mutations. Over 80 different point mutations, 6 insertions, 7 small deletions, and 60 large deletions have been characterised. Repetitive mutation has been proved for at least 16 CpG sites. All nonsense mutations cause severe disease. Most missense mutations appear to cause instability of the protein, but some are associated with production of dysfunctional factor VIII molecules, thereby localising functionally critical regions of the cofactor. Variable phenotype has been observed in association with three of the latter class of genotype. This catalogue of gene lesions in Haemophilia A will be updated annually.

Base Sequence↗
PubMed1991

The molecular basis of hemophilia A.

Due to new, sensitive methodologies, the rate at which factor VIII gene mutations are found is increasing rapidly. The next five years should lead to the discovery of a wide range of defects as well as potential new hot-spots for mutations. Advances in understanding the protein will also provide new insights into the effects of particular mutations. Tremendous strides have been made in carrier detection and prenatal diagnosis. Already diagnosis is possible in 70% of cases with the factor VIII intragenic polymorphisms. Although there is still room for improvement in availability, speed, and cost of the test, many families in the United States and Europe are benefiting from this sensitive detection method.

DNA↗