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Biomedical subjects

J Schmidtke

Publications and source records attributed to J Schmidtke.

At least 145 records · Page 8Linked to original sources
PubMed1986

Diagnosis of genetic disease using recombinant DNA.

Recombinant DNA technology promises to make an important contribution to the analysis and diagnosis of inherited human disease. Direct detection and analysis of various genetic defects at the DNA level are now possible using cloned gene or oligonucleotide probes. In addition, the use of restriction fragment length polymorphisms associated with linked DNA segments should permit not only the diagnosis of hitherto undetectable disease states but also the chromosomal localization of the loci responsible. The eventual isolation of disease loci should lead to a better understanding of the molecular basis of inherited disease.

Base Sequence↗
PubMed1986

Exclusion of close linkage between the parathyroid hormone gene and a mutant gene locus causing idiopathic hypoparathyroidism.

A family is presented in which the mother has transmitted primary hypoparathyroidism with early onset and serum PTH (44-68) and C terminal deficiency to her two sons. Restriction enzyme analysis of allelic variation at the PTH gene locus revealed that the disease and the PTH alleles segregate independently. It is therefore concluded that the primary molecular defect leading to this form of hypoparathyroidism is not located within the PTH gene itself.

Adolescent↗
PubMed1986

Regional mapping of six cloned DNA sequences on human chromosome 7.

The regional localization of six cloned DNA sequences on human chromosome 7 was assessed by molecular hybridization to human/rodent cell hybrid DNAs. The allelic distribution and familial segregation of two frequent polymorphisms revealed by two probes are presented.

Alleles↗
PubMed1985

An estimate of unique DNA sequence heterozygosity in the human genome.

Fifteen different restriction fragment length polymorphisms (RFLPs) were detected in the human genome using 19 cloned DNA segments, derived from flow-sorted metaphase chromosomes or total genomic DNA, as hybridization probes. Since these clones were selected at random with respect to their coding potential, their analysis permitted an unbiased estimate of single-copy DNA sequence heterozygosity in the human genome. Since our estimate (h = 0.0037) is an order of magnitude higher than previous estimates derived from protein data, most of the polymorphic variation present in the genome must occur in non-coding sequences. In addition, it was confirmed that enzymes containing the dinucleotide CpG in their recognition sequence detect more polymorphic variation than those that do not contain CpG.

Base Sequence↗
PubMed1985

A male with a monocentric Yq isochromosome and presence of a Yp-specific DNA sequence.

We describe clinical features and laboratory findings in a physically and mentally retarded male with underdeveloped testes, a seemingly monocentric isochromosome of Yq but the presence of a Yp-specific DNA sequence at a single dose of unknown genomic localisation, and the presence of H-Y antigen at normal male titer. Our data contribute to the fine mapping of the human Y chromosome by correlating phenotypic features with results from karyotypic, immunologic, and molecular hybridisation analyses.

Adolescent↗
PubMed1985

[Familial, structural aberration of the Y chromosome with fertility disorders].

Cytogenetic studies on a patient with Klinefelter's syndrome revealed an inherited, structural aberration of the Y-chromosome which has not been described before. The aberrant Y-chromosome was characterized by eight different banding methods. The value of individual staining techniques in studies on Y-heterochromatin aberrations is emphasized. Analysis of the cytogenetic studies (banding methods, restriction endonuclease of DNA, and measurement of the length of the Y-chromosome) permits an interpretation to be made on how the aberrant Y-chromosome originated. The functions of the Y-chromosome are discussed. The decrease in fertility (cryptozoospermia) in the two brothers with the same aberrant Y-chromosome was striking.

Adolescent↗
PubMed1984

DNA restriction fragment length polymorphisms and heterozygosity in the human genome.

A list is presented of published reports of DNA polymorphisms found in the human genome by restriction enzyme analysis. While the list indicates the large number of restriction fragment length polymorphisms (RFLPs) detected to date, the information collated is insufficient to permit an estimate of heterozygosity for the genome as a whole. Data from our laboratory are therefore also presented on RFLPs detected using a random sample of cloned DNA segments. Such an analysis has permitted a first unbiassed estimate of heterozygosity for the human genome. Since this figure is an order of magnitude higher than previous estimates derived from protein data, the majority of polymorphic variation present in the human genome must, by implication, occur in noncoding sequences. In addition it was confirmed that enzymes containing the dinucleotide CpG in their recognition sequences detect more polymorphic variation than those that do not contain a CpG. Also presented are the clinical applications of DNA polymorphisms in the diagnosis of human genetic disease.

Chromosome Mapping↗
PubMed1984

Mean corpuscular hemoglobin is increased in Martin-Bell syndrome.

Studying the blood picture of 11 patients with Martin-Bell syndrome, we found the erythrocytes relatively hyperchromic when compared to the data from 171 matched controls living in the same institution. Because mean corpuscular hemoglobin is increased also in patients with folic acid deficiency states, we feel that our data provide further evidence that Martin-Bell syndrome is an inherited disease of folate metabolism.

Adult↗
PubMed1984

Restriction fragment length polymorphisms at the human parathyroid hormone gene locus.

Two common Pst I and Taq I restriction enzyme fragment length polymorphisms (RFLPs) were detected at the human parathyroid hormone (PTH) gene locus. The allele frequencies in a Northern German population were 0.578/0.422 (Pst I) and 0.628/0.372 (Taq I). The allele distributions follow Hardy-Weinberg expectations of equilibrium in the population. The Mendelian nature of the polymorphisms were confirmed in family studies.

Alleles↗
PubMed1984

[Diagnosis of fetal sex from trophoblast DNA].

By using recombinant DNA technology fetal sex determination was performed with 13 different trophoblast samples. In all cases trophoblast and fetal sex were identical. The importance of first trimester trophoblast biopsy for the prenatal diagnosis of inherited disease is being discussed.

DNA↗
PubMed1983

Assignment of the human parathyroid hormone gene to chromosome 11.

A panel of human-mouse and human-Chinese hamster cell hybrid DNA's was screened for hybridisation with a fragment of the human parathyroid hormone chromosomal gene. A 7-kilobasepair Msp I restriction fragment homologous to this probe was found to segregate with the human chromosome 11.

Animals↗
PubMed1983

Characterization of a Y/15 translocation by banding methods, distamycin A treatment of lymphocytes and DNA restriction endonuclease analysis.

A de novo 14/21 Robertsonian translocation and a familially inherited Y/15 translocation were observed in a male infant with anomalies of the external genitalia. The Y/15 translocation was confirmed by cultivating lymphocytes in a medium containing distamycin A and by determining the occurrence of the Y-specific DNA sequences by means of Hae III restriction endonuclease analysis. Any connection between the structural chromosomal abnormalities and the symptoms of the infant is highly improbable.

Chromosome Banding↗
PubMed1982

Evolutionary conservation of a common pattern of activity of nucleolus organizers during spermatogenesis in vertebrates.

The patterns of activity of the nucleolus organizer regions (NORs) in the spermatogeneses of ten species of all non-mammalian classes of vertebrates and one species of the cephalochordates were investigated with the silver (Ag)-staining technique. The Ag-stainability of the NORs is a measure of the transcriptional activity of the ribosomal RNA genes. In all species, there is a very similar pattern of NOR-activity in the various stages of spermatogenesis. The qualitative analysis of the Ag-stainability of the NORs was in very good agreement with the results obtained for mammals: Ag-stained NORs are detectable during the entire meiotic prophase up to the pachytene stage, completely absent in the meiotic metaphases I and II, and again demonstrable in early spermatid nuclei. The results confirm the occurrence of postmeiotic reactivation of the RNA genes. The preferential inhibition of rRNA synthesis by low doses of actinomycin D induced a rapid decline of the Ag-stainability of the postmeiotically reactivated NORs. The significance of the evolutionary conservation of the postmeiotic NOR-reactivation is discussed.

Animals↗
PubMed1982

Characterisation of a human Y chromosome repeated sequence and related sequences in higher primates.

The human Y chromosome carries 2000 copies of a tandemly repeated sequence, 2.47 kb long, which constitutes about 20% of the DNA of this chromosome. These sequences are localised on the tip of the long arm of the Y chromosome. Related sequences are present in DNA of females with a related but distinguishable restriction pattern. These autosomal sequences are distributed in tandem arrays on a number of autosomes. Related sequences are also present in gorilla and chimpanzee. In gorilla they resemble the human sequences in their restriction map but are not found on the Y chromosome whereas in chimpanzee the related sequences behave as a 'dispersed' repeat. Changes in the level of methylation of this sequence in different tissues of human males can be detected with the lowest levels found in sperm and placental DNA.

Animals↗