Clinical interpretation of cell-based non-invasive prenatal testing for monogenic disorders including repeat expansion disorders: potentials and pitfalls

Introduction: Circulating fetal cells isolated from maternal blood can be used for prenatal testing, representing a safe alternative to invasive testing. The present study investigated the potential of cell-based noninvasive prenatal testing (NIPT) for diagnosing monogenic disorders dependent on the mode of inheritance.Methods: Maternal blood samples were collected from women opting for prenatal diagnostics for specific monogenic disorders (N = 7). Fetal trophoblasts were enriched and stained using magnetic activated cell sorting and isolated by fluorescens activated single-cell sorting. Individual cells were subject to whole genome amplification, and cells of fetal origin were identified by DNA-profiling using short tandem repeat markers. The amplified fetal DNA was input for genetic testing for autosomal dominant-, autosomal recessive-, X-linked and repeat expansion disorders by direct variant analysis and haplotyping. The cell-based NIPT results were compared with those of invasive testing.Results: In two cases at risk of skeletal dysplasia, caused by variants in the FGFR3 gene (autosomal dominant disorders), cell-based NIPT correctly stated an affected fetus, but allelic dropout of the normal alleles were observed in both cases. Cell-based NIPT gave an accurate result in two cases at risk of autosomal recessive disorders, where the parents carried either different diastrophic dysplasia causing variants in the SLC26A2 gene or the same cystic fibrosis disease-causing variant in the CFTR gene. Cell-based NIPT accurately identified an affected male fetus in a pregnancy at risk of Duchenne muscular dystrophy (DMD gene, X-linked recessive disorders). In two cases at risk of the myotonic dystrophy type 1 (DMPK gene, repeat expansion disorder), cell-based NIPT correctly detected an affected and an unaffected fetus, respectively.Discussion: Circulating fetal cells can be used to detect both maternally- and paternally inherited monogenic disorders irrespective of the type of variant, however, the risk of allelic dropout must be considered. We conclude that the clinical interpretation of the cell-based NIPT result thus varies depending on the disorders’ mode of inheritance

Clinical interpretation of cell-based non-invasive prenatal testing for monogenic disorders including repeat expansion disorders:potentials and pitfalls

Introduction: Circulating fetal cells isolated from maternal blood can be used for prenatal testing, representing a safe alternative to invasive testing. The present study investigated the potential of cell-based noninvasive prenatal testing (NIPT) for diagnosing monogenic disorders dependent on the mode of inheritance. Methods: Maternal blood samples were collected from women opting for prenatal diagnostics for specific monogenic disorders (N = 7). Fetal trophoblasts were enriched and stained using magnetic activated cell sorting and isolated by fluorescens activated single-cell sorting. Individual cells were subject to whole genome amplification, and cells of fetal origin were identified by DNA-profiling using short tandem repeat markers. The amplified fetal DNA was input for genetic testing for autosomal dominant-, autosomal recessive-, X-linked and repeat expansion disorders by direct variant analysis and haplotyping. The cell-based NIPT results were compared with those of invasive testing. Results: In two cases at risk of skeletal dysplasia, caused by variants in the FGFR3 gene (autosomal dominant disorders), cell-based NIPT correctly stated an affected fetus, but allelic dropout of the normal alleles were observed in both cases. Cell-based NIPT gave an accurate result in two cases at risk of autosomal recessive disorders, where the parents carried either different diastrophic dysplasia causing variants in the SLC26A2 gene or the same cystic fibrosis disease-causing variant in the CFTR gene. Cell-based NIPT accurately identified an affected male fetus in a pregnancy at risk of Duchenne muscular dystrophy (DMD gene, X-linked recessive disorders). In two cases at risk of the myotonic dystrophy type 1 (DMPK gene, repeat expansion disorder), cell-based NIPT correctly detected an affected and an unaffected fetus, respectively. Discussion: Circulating fetal cells can be used to detect both maternally- and paternally inherited monogenic disorders irrespective of the type of variant, however, the risk of allelic dropout must be considered. We conclude that the clinical interpretation of the cell-based NIPT result thus varies depending on the disorders' mode of inheritance.</p

Comparison of Recombinant Human Haptocorrin Expressed in Human Embryonic Kidney Cells and Native Haptocorrin

Haptocorrin (HC) is a circulating corrinoid binding protein with unclear function. In contrast to transcobalamin, the other transport protein in blood, HC is heavily glycosylated and binds a variety of cobalamin (Cbl) analogues. HC is present not only in blood but also in various secretions like milk, tears and saliva. No recombinant form of HC has been described so far. We report the expression of recombinant human HC (rhHC) in human embryonic kidney cells. We purified the protein with a yield of 6 mg (90 nmol) per litre of cell culture supernatant. The isolated rhHC behaved as native HC concerning its spectral properties and ability to recognize both Cbl and its baseless analogue cobinamide. Similar to native HC isolated from blood, rhHC bound to the asialoglycoprotein receptor only after removal of terminal sialic acid residues by treatment with neuraminidase. Interestingly, rhHC, that compared to native HC contains four excessive amino acids (…LVPR) at the C-terminus, showed subtle changes in the binding kinetics of Cbl, cobinamide and the fluorescent Cbl conjugate CBC. The recombinant protein has properties very similar to native HC and although showing slightly different ligand binding kinetics, rhHC is valuable for further biochemical and structural studies

Comparison of the transcriptomes of hmgb1 vs Col-0

Accession Number: GSE10638 Platform: GPL6177: Agilent-015059 Arabidopsis 3 Oligo Microarray 4x44K G2519F (Feature Number version) Organism: Arabidopsis thaliana Published on 2008-11-24 Summary: Testing the consequences of the absence of the chromatin-associated HMGB1 protein on the transcriptome in Arabidopsis. Keywords: Comparison of mutant and wildtype samples. Overall Design: Four replicate RNA extractions were performed of each genotype using independent pools of plants. hmgb1#1 (Cy5) vs. Col-0#1 (Cy3) Col-0#2 (Cy5) vs. hmgb1#2 (Cy3) dye-swap hmgb1#3 (Cy5) vs. Col-0#3 (Cy3) Col-0#5 (Cy5) vs. hmgb1#4 (Cy3) dye-swap Samples were hybridized in two dye-swaps. The data were normalized over all 4 hybridizations to obtain one, single log-ratio(Sample/Reference). The raw data files of all four of the hybridizations are attached to the Sample. Contact: Name: Wouter Van Delm Organization: Flanders Institute for Biotechnology (VIB) Deparment: Nucleomics Core Address: Herestraat 49 Box 816 Leuven Belgium Email: [email protected] Phone: +32(0)16 37 31 26 Organization: Agilent Technologies Address: Palo Alto CA 94304 USA Email: [email protected] Phone: 877-424-4536 Web-Link: www.agilent.co

Binding and dissociation kinetics of the fluorescent conjugate CBC and Cbi.

<p>Kinetic measurements revealed a subtle difference between rhHC and native HC. (A) Binding kinetics. rhHC was mixed with either CBC or CBC + Cbl/Cbi (all 0.5 µM), pH 7.5, 22°C. Appearance of rhHC·CBC complex was monitored over time according to increasing fluorescence normalized to the maximal amplitude of the signal. The binding rate constants were calculated by computer fitting (solid lines). (B) Dissociation kinetics. rhHC was mixed with either CBC or the non-fluorescent test ligands Cbl and Cbi (all 1 µM, pH 7.5, 22°C, 2 min incubation), whereupon either Cbl (1 µM) or CBC (1 µM) was added. Change in the concentration of rhHC·CBC complex was monitored over time according to the normalized fluorescent response. Dissociation of Cbi was tested in three different preparations of rhHC (all three curves are presented, see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037421#pone-0037421-t002" target="_blank">Table 2</a>). Best fits are shown by solid lines. The dissociation rate constants were calculated from the linear slopes of the produced charts (examples indicated by dashed lines). Alternative linear slopes are shown for rhHC·Cbl dissociation.</p