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Biomedical subjects

J Schmidtke

Publications and source records attributed to J Schmidtke.

At least 127 records · Page 7Linked to original sources
PubMed1988

DNA analysis of ornithine transcarbamylase deficiency.

By analysing the restriction fragment length polymorphism (RFLP) detected by an ornithinetranscarbamylase (OTC) gene specific DNA probe, we followed the segregation of the defective gene in two families with OTC deficiency (X-linked disease). We were able to exclude some female family members as carriers. In one case a doubtful result obtained in a biochemical carrier detection test (by examining the renal orotic acid excretion after a protein load) could be clarified by DNA analysis. In every family with OTC deficiency, carrier detection should be biochemical with additional DNA analysis. Previous results of the biochemical carrier test should be controlled by DNA analysis, especially when "normal" results were obtained.

Amino Acid Metabolism, Inborn Errors↗
PubMed1988

A comprehensive list of cloned human DNA sequences.

A list of DNA sequences cloned from the human genome is presented. Intended as a guide to clone availability, this list includes published reports of cDNA, genomic and synthetic clones comprising gene and pseudogene sequences, uncharacterised DNA segments and repetitive DNA elements.

Cloning, Molecular↗
PubMed1988

Rare Ha-ras and c-mos alleles in patients with intracranial tumors.

The occurrence of rare hypervariable Ha-ras alleles or of a rare c-mos allele in white blood cell DNA is claimed to be associated with susceptibility to cancer. We analyzed a group of patients with intracranial tumors to determine whether the occurrence of rare alleles at the Ha-ras locus and at the c-mos locus was increased in comparison with normal individuals. We found a higher incidence of rare hypervariable Ha-ras alleles (9.5% to 3%) and a 5 kilobase EcoRI c-mos allele (2.5% to 0%) in the patients. These results are consistent with the opinion that such unusual alleles are associated with a predisposition to intracranial tumors.

Adolescent↗
PubMed1987

A human Y-chromosomal DNA sequence expressed in testicular tissue.

Clone pJA36B (DYS14) was isolated from a human Y chromosome enriched cosmid library. Southern blot analysis revealed a male-specific hybridization pattern. Deletion mapping with patients' DNA localized pJA36B to the median region of Yp, being present in the DNA of nine of fifteen XX-males tested so far and therefore localized in the region neighbouring the TDF-locus. Northern blot analysis showed a transcription signal in poly(A)+ RNA of human testis. Sequence analysis of the genomic DNA sequence revealed an open reading frame of 522 basepairs in the absence of control or signal sequences for the regulation of transcription or polyadenylation. This suggests that only one exon of a translatable sequence is present in clone pJA36B. A computer aided search revealed no significant homologies with known DNA or protein sequences.

Amino Acid Sequence↗
PubMed1987

Linkage relationships and allelic associations of the cystic fibrosis locus and four marker loci.

The linkage relationships between the cystic fibrosis (CF) locus and four marker loci (MET-H, MET-D, D7S8 and D7S16), allelic associations between these loci and the extent of informativity at these marker loci were investigated in a sample of 206 families with at least one child affected by CF. The data were contributed by 11 laboratories from Europe and Israel. The maximum lod scores and recombination frequency estimates (luminal diameter) (and confidence limits of luminal diameter) were: 18.3 at luminal diameter = 0.007 (0.001-0.038) for CF vs. MET, 11.0 at luminal diameter = 0.016 (0.001-0.068) for CF vs. D7S8, and 5.7 at luminal diameter = 0.0 (0.0-0.064) for CF vs. D7S16. A gene order of CF-MET-D7S8 was best supported by the data, but its preference to the order D7S8-CF-MET is mainly based on one single family. There are significant allelic associations between CF, MET, D7S8 and D7S16; these allelic associations affect the risk of random individuals to be carriers of CF.

Alleles↗
PubMed1987

Genetic linkage study between the loci for Duchenne and Becker muscular dystrophy and nine X-chromosomal DNA markers.

A set of nine polymorphic loci defined by DNA probes was studied for linkage with the disease locus in ten families with a history of Duchenne muscular dystrophy (DMD), and three families with a history of Becker muscular dystrophy (BMD). The results confirm DMD and BMD linkage to all marker loci and suggest closer linkage of several probes than hitherto detected. This will be of practical interest for risk calculations in affected families.

Alleles↗
PubMed1987

Diagnosis of genetic disease using recombinant DNA. Supplement.

Recombinant DNA methodology has greatly increased our knowledge of the molecular pathology of the human genome at the same time as providing the means to diagnose inherited disease as the DNA level. We present here a list of recent reports of both direct and indirect analysis of human inherited disease which is intended to serve as a guide to current molecular genetic approaches to diagnostic medicine.

DNA, Recombinant↗
PubMed1987

Regional localization and characterization of a DNA segment on the long arm of chromosome 21.

A human genomic DNA fragment, pAM37 (HGM8; D21S22), was mapped to chromosome 21q2.1-q2.21 by in situ hybridization. This segment is therefore situated on the boundary of the "pathological region" of Down syndrome. A genomic restriction map encompassing 35 kb of chromosome 21 was derived and two restriction fragment length polymorphisms (RFLPs) were mapped and characterized. A homologous sequence was detected in the mouse genome but no homologous RNA was detected in a range of human tissues. This DNA segment will contribute to the linkage mapping of chromosome 21 and will facilitate delineation of the pathological region of Down syndrome.

Chromosome Banding↗
PubMed1987

A comprehensive list of cloned human DNA sequences.

A list of DNA sequences cloned from the human genome is presented. Intended as a guide to clone availability, this list includes published reports of cDNA, genomic and synthetic clones comprising gene and pseudogene sequences, uncharacterized DNA segments and repetitive DNA elements.

Base Sequence↗
PubMed1987

Segregation of all four major fibrillar collagen genes in the Marfan syndrome.

Linkage markers at or close to the genes encoding the three major fibrillar collagens were used to analyze the segregation of these loci in six pedigrees with dominantly inherited Marfan syndrome. Four pedigrees were discordant at one of the Type I collagen loci (COL1A2), and, of these, two were discordant at the other Type I locus (COL1A1). The Marfan syndrome also segregated independently of the structural loci for Type II and Type III collagen in these two families. This is evidence against the Marfan syndrome being, in general, due to mutations in the major fibrillar collagen genes.

Adolescent↗
PubMed1987

[Prenatal diagnosis of cystic fibrosis with recombinant DNA methods].

Cystic fibrosis is one of the commonest genetic disorders with about 1 in 3000 newborns being affected. The molecular etiology of the disease is still not known. In spite of improved therapy the life expectancy is markedly reduced. Many parents of a child affected by CF request a prenatal diagnosis, when a further child is expected. By using molecular genetic methods the prenatal detection of CF is possible now with great accuracy in most families. This review describes the principles of the genetics and the diagnosis of the disease. Case reports illustrate risk figure ascertainment. Preconditions for performing the diagnosis in individual cases are outlined, and a guide to the practical approach is given.

Cystic Fibrosis↗
PubMed1986

Rett syndrome--search for genetic markers.

We have studied 8 girls with Rett syndrome, including 2 sisters. Their ages ranged from 1 to 26 years. The youngest patient presented with developmental delay and atypical infantile spasms. The oldest was the sister of a patient followed over a period of 13 years and showed the typical history and clinical picture of Rett syndrome. DNA from white blood cells of these patients was investigated for alterations in the OTC structural gene. As compared to normal control individuals no gross alterations occur in the OTC structural genes of patients with Rett's syndrome.

Adolescent↗
PubMed1986

Clustered GATA repeats (Bkm sequences) on the human Y chromosome.

Sixty eight individual clones of a human Y chromosome cosmid library were screened for the presence of GATA repeats, the major component of Bkm-related DNA sequences. Nine cosmid clones were found to cross-hybridize. The sequence organization of the repetitive base quadruplet GATA was analyzed using synthetic oligonucleotide probes. Subclones of GATA-positive cosmid clones were used for chromosomal localization of the Y-derived DNA sequences thus revealing male-specificity or male-female homology.

Cosmids↗
PubMed1986

Chromosome assignment and restriction fragment length polymorphism analysis of the anonymous DNA probe B79a at 7q22 (HMG8 assignment D7S13).

The anonymous DNA fragment B79a, which had previously been located to chromosome 7cen-7q22, has been more accurately assigned to 7q22 by dosage analysis in a patient hemizygous for a deletion of that region. By examination of a panel of genomic DNAs from unrelated individuals, digested with a number of different restriction enzymes, we have identified two frequent RFLPs detected by B79a. This probe will be important in the analysis of cystic fibrosis which has been mapped to the region around 7q22.

Chromosome Mapping↗
PubMed1986

Human DNA sequences isolated with an immunoglobulin switch region probe: sequence, chromosomal localization, and restriction fragment length polymorphisms.

We have screened a human genomic DNA library with an immunoglobulin (Ig) derived switch (S) region specific probe for homologous sequences. Five Ig independent phage clones were isolated and characterized. The S sequence homologous DNA fragments are short compared to the S region sequences. Ig independent S sequences are flanked by highly repetitive DNA elements and perfect inverted repeats can be demonstrated in their close vicinity. Using subclones of S homologous sequences restriction fragment length polymorphisms were shown within DNA of different T cell leukemias, Burkitt lymphomas, lymphoblastoid cell lines, and DNA of healthy individuals. One of the five clones isolated with the S region probe was evidently localized to chromosome 2 and/or 10 and showed a complex hybridisation pattern with several different human DNAs. S homologous sequences of another clone are most likely localized on chromosome 1. It is possible that these Ig independent S sequences have arisen by amplification and transposition and that they are involved in genetic recombination.

Base Sequence↗