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G Tromp

Publications and source records attributed to G Tromp.

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

Deletion of 19 base pairs in intron 13 of the gene for the pro alpha 2(I) chain of type-I procollagen (COL1A2) causes exon skipping in a proband with type-I osteogenesis imperfecta.

Skin fibroblasts from a proband with mild osteogenesis imperfecta (type I) synthesized normal pro alpha 2(I) chains and shortened pro alpha 2(I) chains of type-I procollagen. The type-I collagen that contained the shortened alpha 2(I) chains was thermally unstable in that it was cleaved at 30 degrees C by a mixture of trypsin and chymotrypsin. The mutation generating the shortened pro alpha 2(I) chains was shown to be a deletion of 19 base pairs from +4 to +22 of intron 13 of the COL1A2 gene by sequencing of genomic DNA and allele-specific oligonucleotide hybridization. The same mutation was found in the proband's affected father. Probe-protection experiments with S1 nuclease demonstrated that about 88% of the RNA transcripts from the mutated allele were spliced by exon skipping from exon 12 to exon 14 and that about 12% of the RNA transcripts were normally spliced. There was no evidence for use of cryptic splice sites, even though two cryptic splice sites had more favorable statistical scores and delta G degree 37 values than the new site that was created by the mutation and that was used for splicing of 12% of the transcripts into a normal mRNA. Comparison of the results with observations on 17 previously reported mutations that produced in-frame deletions of amino acids from the triple-helical domain of type-I collagen indicated that deletions in the N-terminal half of the alpha 2(I) chain tended to produce milder phenotypes than similar deletions elsewhere in the alpha 1(I) or alpha 2(I) chains.

Adolescent↗
PubMed1993

Sequencing of cDNA from 50 unrelated patients reveals that mutations in the triple-helical domain of type III procollagen are an infrequent cause of aortic aneurysms.

Detailed DNA sequencing of the triple-helical domain of type III procollagen was carried out on cDNA prepared from 54 patients with aortic aneurysms. The 43 male and 11 female patients originated from 50 different families and five different nationalities. 43 patients had at least one additional blood relative who had aneurysms. Five overlapping asymmetric PCR products, covering all the coding sequences of the triple-helical domain of type III procollagen, were sequenced with 28 specific sequencing primers. Analysis of the sequencing gels revealed only two nucleotide changes that altered the structure of the protein. One was a substitution of threonine for proline at amino acid position 501 and its functional importance was not clearly established. The other was a substitution of arginine for an obligatory glycine at amino acid position 136. In 40 of the 54 patients, detection of a polymorphism in the mRNA established that both alleles were expressed. The results indicate that mutations in type III procollagen are the cause of only about 2% of aortic aneurysms.

Adult↗
PubMed1993

Efficient DNA sequencing on microtiter plates using dried reagents and Bst DNA polymerase.

Sequenase, Taq DNA polymerase and Bst DNA polymerase were tested for sequencing of DNA on microtiter plates using dried down reagents. Several parameters were investigated to expedite the drying process while minimizing damage to the enzyme. Sequenase did not tolerate drying very well, and frequently generated sequences with weak signals and many sites of premature termination. With Taq DNA polymerase it was possible to obtain sequences of good quality. However, there was considerable variation of results between experiments and between batches of microtiter plates. Bst DNA polymerase generated sequences of excellent quality. It was stable for more than a week in dried-down state at -20 degrees C and at least overnight at room temperature. The method described here using Bst DNA polymerase is well suited for laboratory robots and workstations that typically employ 96-well microtiter plates.

Automation↗
PubMed1992

A 15 base-pair AT-rich variable number tandem repeat in the type III procollagen gene (COL3A1) as an informative marker for 2q31-2q32.3.

Segments of repeating DNA, termed variable number tandem repeats, within the genome are often used as polymorphic markers. Here we report such a repeat in the intervening sequence 25 of the type III procollagen gene (COL3A1) located at 2q31-q32.3. The region containing intervening sequence 25 of the COL3A1 gene was amplified using the polymerase chain reaction and the products were analyzed by agarose gel electrophoresis and dideoxynucleotide sequencing. The repeat consisted of an AT-rich unit of 15 base-pairs (ATATATATATGAGAC). Seven different alleles were identified containing between three and nine repeats of the 15 base-pair unit. The allele heterozygosity was 73% in 117 unrelated individuals. The alleles were shown to be inherited in a Mendelian fashion in three large families. This marker should prove useful in linkage studies for COL3A1, and for linkage studies of other genes on the long arm of chromosome 2. The information extends and complements a report on the same repeat recently published by Lee et al. (J. Biol. Chem. 266: 5256, 1991 a).

Alleles↗
PubMed1992

Substitution of aspartate for glycine 1018 in the type III procollagen (COL3A1) gene causes type IV Ehlers-Danlos syndrome: the mutated allele is present in most blood leukocytes of the asymptomatic and mosaic mother.

A proband with arterial ruptures and skin changes characteristic of the type IV variant of Ehlers-Danlos syndrome was found to have a single-base mutation in the type III procollagen gene, which converted the codon for glycine at amino acid position 1018 to a codon for aspartate. (Amino acid positions are numbered by the standard convention in which the first glycine of the triple-helical domain of an alpha chain is number 1. The numbers of positions in the alpha 1(III) chains can be converted to positions in the human pro alpha(III) chain by adding 167.) Nucleotide sequencing of overlapping PCR products in which the two alleles were distinguished demonstrated that the mutation of glycine 1018 was the only mutation that changed the primary structure of type III procollagen. The glycine substitution markedly decreased the amount of type III procollagen secreted into the medium by cultured skin fibroblasts from the proband. It is surprising that the same mutation was found in about 94% of the peripheral blood leukocytes from the proband's asymptomatic 72-year-old mother. Other tissues from the mother contained the mutated allele; it was present in 0%-100% of different samples of hair cells and in about 40% of cells from the oral epithelium. Therefore, the mother was a mosaic for the mutation. Since the mutated allele was present in cells derived from all three germ layers, the results indicated that the mutation arose by the late blastocyst stage of development. The results also indicate that assays of blood leukocytes do not always reveal mosaicism or predict phenotypic involvement of tissues, such as blood vessels, that are derived from the same embryonic cells as are leukocytes.

Adult↗
PubMed1991

Exclusion of COL1A1, COL1A2, and COL3A1 genes as candidate genes for Ehlers-Danlos syndrome type I in one large family.

Ehlers-Danlos syndrome (EDS) type I is a generalized connective tissue disorder, the major manifestations of which are soft, velvety hyperextensible skin and moderately severe joint hypermobility. The gene defect or defects causing EDS type I have not yet been defined, but previous observations suggested that the syndrome may be caused by mutations in the genes for type-I collagen (COL1A1 and COL1A2) or type-III collagen (COL3A1). Here, we performed linkage studies for these three genes in large Azerbaijanian family with EDS type I. Three polymorphisms in the COL3A1 gene, two in the COL1A1 gene, and one in the COL1A2 gene were tested using the polymerase chain reaction. The data obtained excluded linkage of any of the three genes to EDS type I in the family.

Base Sequence↗
PubMed1991

Mutations in collagen genes: causes of rare and some common diseases in humans.

More than 70 mutations in the two structural genes for type I procollagen (COL1A1 and COL1A2) have been found in probands with osteogenesis imperfecta, a heritable disease of children characterized by fragility of bone and other tissues rich in type I collagen. The mutations include deletions, insertions, RNA splicing mutations, and single-base substitutions that convert a codon for glycine to a codon for an amino acid with a bulkier side chain. With a few exceptions, the most severe phenotypes of the disease are explained largely by synthesis of structurally defective pro alpha chains of type I procollagen that either interfere with the folding of the triple helix or with self-assembly of collagen into fibrils. The results emphasize the extent to which the zipperlike folding of the collagen triple helix and the self-assembly of collagen fibrils depend on the principle of nucleated growth whereby a few subunits form a nucleus and the nucleus is then propagated to generate a large structure with a precisely defined architecture. The principle of nucleated growth is a highly efficient mechanism for the assembly of large structures, but biological systems that depend extensively on nucleated growth are highly vulnerable to mutations that cause synthesis of structurally abnormal but partially functional subunits. Recently, several mutations in three other collagen genes (COL2A1, COL3A1, and COL4A5) have been found in probands with genetic diseases involving tissues rich in these collagens. Most of the probands have rare genetic diseases but a few appear to have phenotypes that are difficult to distinguish from more common disorders such as osteoarthritis, osteoporosis, and aortic aneurysms. Therefore, the results suggest that mutations in procollagen genes may cause a wide spectrum of both rare and common human diseases.

Animals↗
PubMed1991

A mutation in the pro alpha 2(I) gene (COL1A2) for type I procollagen in Ehlers-Danlos syndrome type VII: evidence suggesting that skipping of exon 6 in RNA splicing may be a common cause of the phenotype.

Fibroblasts from a proband with Ehlers-Danlos syndrome type VII synthesized approximately equal amounts of normal and shortened pro alpha 2(I) chains of type I procollagen. Nuclease S1 probe protection experiments with mRNA demonstrated that the pro alpha 2(I) chains were shortened because of a deletion of most or all of the 54 nucleotides in exon 6, the exon that contains codons for the cleavage site for procollagen N-proteinase. Sequencing of genomic clones revealed a single-base mutation that converted the first nucleotide of intron 6 from G to A. Therefore, the mutation was a change, in the -GT-consensus splice site, that produced efficient exon skipping. Allele-specific oligonucleotide hybridizations demonstrated that the proband's mother, father, and brother did not have the mutation. Therefore, the mutation was a sporadic one. Analysis of potential 5' splice sites in the 5' end of intron 6 indicated that none had favorable values by the two commonly employed techniques for evaluating such sites. The proband is the fourth reported proband with Ehlers-Danlos syndrome VII with a single-base mutation that causes skipping of exon 6 in the splicing of RNA from either the COL1A1 gene or COL1A2 gene. No other mutations in the two type I procollagen genes have been found in the syndrome. Therefore, such mutations may be a common cause of the phenotype. The primers developed should be useful in screening for the same or similar mutations causing the disease.

Alleles↗
PubMed1990

Identical G+1 to A mutations in three different introns of the type III procollagen gene (COL3A1) produce different patterns of RNA splicing in three variants of Ehlers-Danlos syndrome. IV. An explanation for exon skipping some mutations and not others.

Identical G+1 mutations in three different introns of the gene for type III procollagen (COL3A1) that cause aberrant splicing of RNA were found in three probands with life-threatening variants of Ehlers-Danlos syndrome. Because the three mutations were in a gene with multiple and homologous exons, they provided an interesting test for factors that influence aberrant splicing. The G+1 to A mutation in intron 16 caused extensive exon skipping, the G+1 to A mutation in intron 20 caused both use of a cryptic splice site and retention of all the intron sequences, and the G+1 to A mutation in intron 42 caused efficient use of a single cryptic splice site. The different patterns of RNA splicing were not explained by evaluation of potential cryptic splice sites in the introns by either their homology with 5'-splice sites from other genes or by their delta G(0)37 values for binding to U1 RNA. Instead, the results suggested that the patterns of aberrant RNA splicing were primarily determined by the relative rates at which adjacent introns were normally spliced.

Adenine↗
PubMed1990

A mutation in the gene for type III procollagen (COL3A1) in a family with aortic aneurysms.

Experiments were carried out to test the hypothesis that familial aortic aneurysms, either thoracic or abdominal, are caused by mutations in the gene for type III procollagen (COL3A1) similar to mutations in the same gene that have been shown to cause rupture of aorta and other disastrous consequences in the rare genetic disorder known as Ehlers-Danlos syndrome type IV. A family was identified through a 37-yr-old female captain in the United States Air Force who was scrutinized only because many of her direct blood relatives had died of ruptured aortic aneurysms. The woman was heterozygous for a single-base mutation that converted the codon for glycine 619 of the alpha 1(III) chain of type III procollagen to a codon for arginine. Studies on cultured skin fibroblasts demonstrated the mutation caused synthesis of type III procollagen that had a decreased temperature for thermal unfolding of the protein. The same mutation was identified in DNA extracted from pathologic specimens from her mother who had died at the age of 34 and a maternal aunt who died at the age of 55 of aortic aneurysms. Examination of DNA from samples of saliva revealed that the woman's daughter, her son, a brother, and an aunt also had the mutation. The results demonstrated that mutations in the type III procollagen gene can cause familial aortic aneurysms and that DNA tests for such mutations can identify individuals at risk for aneurysms.

Adult↗
PubMed1990

Inheritance of an RNA splicing mutation (G+ 1 IVS20) in the type III procollagen gene (COL3A1) in a family having aortic aneurysms and easy bruisability: phenotypic overlap between familial arterial aneurysms and Ehlers-Danlos syndrome type IV.

Inheritance of a single base mutation in the type III procollagen gene (COL3A1) was studied in a family with aortic aneurysms and easy bruisability. The mutation was a substitution of A for G+ 1 of intron 20 of the gene and caused aberrant splicing of RNA transcribed from the mutated allele. The phenotype in the family included aortic aneurysms that ruptured and produced death. It also included easy bruisability, but it did not include other characteristic features of Ehlers-Danlos syndrome type IV, such as ecchymoses, abnormal scarring, or prominent subcutaneous blood vessels. The data from the family, together with a review of other probands with mutations in the type III procollagen gene, indicated that there is phenotypic overlap between Ehlers-Danlos syndrome type IV and familial arterial aneurysms not associated with any overlap between Ehlers-Danlos syndrome type IV and familial arterial aneurysms not associated with any of the striking changes in skin originally cited as a characteristic feature of Ehlers-Danlos syndrome type IV. In addition, the results suggested that DNA tests for mutations in the type III procollagen gene may be useful to identify individuals predisposed to developing arterial aneurysms.

Adult↗