F. von Eggeling

Small supernumerary marker chromosomes--progress towards a genotype-phenotype correlation

Small supernumerary marker chromosomes (sSMC) are still a major problem in clinical cytogenetics as they are too small to be characterized for their chromosomal origin by traditional banding techniques, but require molecular cytogenetic techniques for their identification. Apart from the correlation of about one third of the sSMC cases with a specific clinical picture, i.e. the i(18p), der(22), i(12p) (Pallister Killian syndrome) and inv dup(22) (cat-eye) syndromes, most of the remaining sSMC have not yet been correlated with clinical syndromes. Recently, we reviewed the available >1600 sSMC cases (Liehr T, sSMC homepage: http://mti-n.mti.uni-jena.de/∼huwww/MOL_ZYTO/sSMC.htm). A total of 387 cases (including the 45 new cases reported here) have been molecularly cytogenetically characterized with regard to their chromosomal origin, the presence of euchromatin, heterochromatin and satellite material. Based on analysis of these cases we present the first draft of a basic genotype-phenotype correlation for sSMC for all human chromosomes apart from the chromosomes Y, 10, 11 and 13.

Determination of the origin of single nucleated cells in maternal circulation by means of random PCR and a set of length polymorphisms

Abstract Non-invasive prenatal diagnosis on fetal nucleated erythrocytes from the maternal circulation is hampered by the small number of nucleated erythrocytes and the uncertainty as to whether they are of fetal or maternal origin. To overcome the latter limitation, single nucleated erythrocytes were separated and enriched from maternal blood by a triple density gradient and a monoclonal antibody (CD71) in combination with a magnetic activated cell sorter. Single nucleated cells were microscopically examined, individually collected with extended Pasteur pipettes, and each transferred into separate caps for the polymerase chain reaction (PCR). The DNA of the single nucleated erythrocytes was amplified at least 50-fold with a random PCR technique, viz., primer extension preamplification. Precise differentiation between maternal and fetal nucleated erythrocytes was achieved via PCR by using primers flanking highly polymorphic nucleotide repeats (D1S53, ACTBP2 and D21S11) and with a XY-specific primer pair (amelogenin). A total of 134 putative nucleated erythrocytes were analyzed from blood samples of 19 pregnant women. With the help of the polymorphic repeats, 25% were assigned as being of maternal origin, 26% of fetal origin, and 48% were uninformative. In cases with male fetuses, the amelogenin primers revealed 30% of cells to be fetal nucleated erythrocytes, the remaining 70% being of maternal origin. The results indicate that the combination of random PCR and PCR-mediated polymorphism analysis on the DNA of single nucleated erythrocytes is a useful technique for non-invasive prenatal diagnosis.

Supernumerary small marker chromosome (SMC) and uniparental disomy 22 in a child with confined placental mosaicism of trisomy 22: trisomy rescue due to marker chromosome formation.

Trisomy rescue is one of various proposed mechanisms in formation of supernumerary small marker chromosomes (SMC) and uniparental disomy (UPD). In the present report a small de novo marker chromosome derived from chromosome 14 or 22 was diagnosed at prenatal diagnosis due to maternal age. Follow up investigations at birth revealed mosaicism 47,XX,+mar/46,XX. Using FISH, the marker was positive for the probe D14/22Z1, but negative for the probes midi 54 and D22Z4. Using three informative markers both chromosomes 22 were shown to be inherited from the mother (UPDmat). The results are consistent with nondisjunction at maternal meiosis I. The girl is 18 months old now and phenotypically normal. Cardiac and abdominal malformations were excluded by sonographic examinations. Motor and mental development is according to or ahead of developmental milestones (free walking with 10 months, first words at 12 months). The case confirms that maternal UPD 22 most likely is not associated with clinical abnormalities. According to FISH results, UPD 22, and 47,XX,+22 in the placenta, we conclude that the SMC was derived from alpha satellite sequences of chromosome 22. This case for the first time gives evidence that early postzygotic reduction of a chromosome to a small marker chromosome is a real existing mechanism to rescue a conceptus with trisomy.

Identifizierung von Biomarkern und therapeutischen Targets beim Nierenzellkarzinom mittels ProteinChip-Technologie

ZusammenfassungZur komplexen Erfassung tumorbiologischer Veränderungen ist es notwendig, neben der DNA- und RNA-Ebene auch die Proteinebene zu analysieren. Mit der Methode der SELDI-TOF-MS (surface enhanced laser desorption/ionization time-of-flight mass spectrometry) steht nun ein Verfahren zur Verfügung, das die hochsensitive Detektion von spezifischen Proteinprofilen bei hohem Probendurchsatz erlaubt. Für die Nierentumoren konnten inzwischen spezifische Proteinmuster im Serum aufgezeigt werden, die die Grundlage für die Entwicklung spezifischer Biomarker darstellen. Erste Proteine, wie das „Serumamyloid Alpha“ (SAA) konnten identifiziert werden.Die Analyse der Tumorgewebe wird zur Aufklärung der Tumorbiologie und zur Verbesserung der Subklassifizierung auch unter Berücksichtigung der Prognose führen. Proteomanalysen in Korrelation zur Therapie eröffnen die Möglichkeit der Aufklärung der biologischen Therapieeffekte einerseits und die Identifizierung von Biomarkern zur Patientenselektion und Therapieüberwachung andererseits. Erste Ansätze bei Nierenzelltumoren werden aufgezeigt.AbstractIn order to understand tumour biology in its complexity, it is necessary to investigate the proteomics in addition to the DNA and RNA level. SELDI-TOF-MS represents a new technology allowing a highly sensitive high-throughput analysis to detect specific protein profiles. In renal cancer, it was possible to define specific protein patterns in serum. Several proteins have been identified, i.e. serum amyloid alpha (SAA).Analysis of tumour tissues leads to a better understanding of tumour biology and provides the basis for differential classification and evaluation of prognosis. Investigation of the proteome concerning therapy results opens up the possibility of assessing downstream effects on the one hand and identifying biomarkers for selection of patients and therapy monitoring on the other hand. This review presents the first results for renal cancer.

Molecular cytogenetic characterization of a de novo supernumerary ring chromosome 7 resulting in partial trisomy, tetrasomy, and hexasomy in a child with dysmorphic signs, congenital heart defect, and developmental delay.

We report on a girl with mosaicism (65%) of a de novo supernumerary ring chromosome 7. The main clinical features were delayed psychomotor development, congenital heart defect, facial dysmorphisms, and long hands, fingers, feet and toes. Molecular cytogenetic analysis revealed that the ring chromosome was duplicated in 20% of the analyzed metaphases with marker chromosome and quadruplicated in 5% thereof. Uniparental disomy (UPD) of the two normal sister chromosomes 7 was excluded. This is, to our knowledge, the first report of a partial tetrasomy to hexasomy due to a ring chromosome 7. Additionally, the ring evolution could be reconstructed according to the FISH‐results.

Is There a Yet Unreported Unbalanced Chromosomal Abnormality without Phenotypic Consequences in Proximal 4p

Unbalanced chromosomal abnormalities (UBCA) are reported for >50 euchromatic regions of almost all human autosomes. UBCA are comprised of a few megabases of DNA, and carriers are in many cases clinically healthy. Here we report on a partial trisomy of chromosome 4 of the centromere-near region of the short arm of chromosome 4 present as a small supernumerary marker chromosome (sSMC). The sSMC was present in >70% of amnion cells and in 60% of placenta. Further delineation of the size of the duplicated region was done by molecular cytogenetics and array comparative genomic hybridization. Even though the sSMC lead to a partial trisomy of ∼9 megabase pairs, a healthy child was born, developing normally at 1 year of age. No comparable cases are available in the literature. Thus, we discuss here the possibility of having found a yet unrecognized chromosomal region subject to UBCA.

Invited Article: Comparison of hyperspectral coherent Raman scattering microscopies for biomedical applications

Raman scattering based imaging represents a very powerful optical tool for biomedical diagnostics. Different Raman signatures obtained by distinct tissue structures and disease induced changes provoke sophisticated analysis of the hyperspectral Raman datasets. While the analysis of linear Raman spectroscopic tissue data is quite established, the evaluation of hyperspectral nonlinear Raman data has not yet been evaluated in great detail. The two most common nonlinear Raman methods are CARS (coherent anti-Stokes Raman scattering) and SRS (stimulated Raman scattering) spectroscopy. Specifically the linear concentration dependence of SRS as compared to the quadratic dependence of CARS has fostered the application of SRS tissue imaging. Here, we applied spectral processing to hyperspectral SRS and CARS data for tissue characterization. We could demonstrate for the first time that similar cluster distributions can be obtained for multispectral CARS and SRS data but that clustering is based on different spectral features due to interference effects in CARS and the different concentration dependence of CARS and SRS. It is shown that a direct combination of CARS and SRS data does not improve the clustering results.Raman scattering based imaging represents a very powerful optical tool for biomedical diagnostics. Different Raman signatures obtained by distinct tissue structures and disease induced changes provoke sophisticated analysis of the hyperspectral Raman datasets. While the analysis of linear Raman spectroscopic tissue data is quite established, the evaluation of hyperspectral nonlinear Raman data has not yet been evaluated in great detail. The two most common nonlinear Raman methods are CARS (coherent anti-Stokes Raman scattering) and SRS (stimulated Raman scattering) spectroscopy. Specifically the linear concentration dependence of SRS as compared to the quadratic dependence of CARS has fostered the application of SRS tissue imaging. Here, we applied spectral processing to hyperspectral SRS and CARS data for tissue characterization. We could demonstrate for the first time that similar cluster distributions can be obtained for multispectral CARS and SRS data but that clustering is based on different spectral...