Reports from the Fifth EAHN Meeting in Tallinn

The fifth international meeting of the European Architectural History Network was held in Tallinn, at the National Library of Estonia, from 13 to 16 June 2018. The reports from this meeting aim to capture some of the main themes that came up during four intense days of academic discussions and exchange, meetings, and free-form interaction in different spatial and social settings. After the introduction by Andres Kurg, host of the Tallinn Meeting, five delegates review the five thematic tracks which organised the selected sessions and ran in parallel throughout the three days of the conference: Mediations, Comparative Modernities, Peripheries, Discovery and Persistence, and Body and Mind. In his closing keynote lecture, Reinhold Martin from Columbia University further reflected on the ample critical discussions which had taken place throughout the conference

Karyotype of the blastocoel fluid demonstrates low concordance with both trophectoderm and inner cell mass

Objective To compare the genomic profiles of blastocoel fluid (BF), inner cell mass (ICM), and trophectoderm (TE) cells derived from the same blastocyst. Design Prospective study. Setting Academic and in vitro fertilization units. Patient(s) Sixteen donated cryopreserved embryos at blastocyst stage. Intervention(s) BF, TE, and ICM cells were retrieved from each blastocyst for chromosome analysis by means of next-generation sequencing (NGS). Main Outcome Measure(s) Aneuploidy screening and assessment of mosaicism in BF, TE and ICM samples with subsequent comparison of genomic profiles between the three blastocyst compartments. Result(s) Out of 16 blastocysts, 10 BF samples and 14 TE and ICM samples provided reliable NGS data for comprehensive chromosome analysis. Only 40.0% of BF-DNA karyotypes were fully concordant with TE or ICM, compared with 85.7% concordance between TE and ICM. In addition, BF-DNA was burdened with mosaic aneuploidies and the total number of affected chromosomes in BF was significantly higher compared with the TE and ICM. Conclusion(s) BF-DNA can be successfully amplified and subjected to NGS, but owing to increased discordance with ICM and TE, BF does not adequately represent the status of the rest of the embryo. To overcome biologic and technical challenges associated with BF sampling and processing, blastocentesis would require improvement in both laboratory protocols and aneuploidy calling algorithms. Therefore, TE biopsy remains the most effective way to predict embryonic karyotype, and the use of BF as a single source of DNA for preimplantation genetic screening is not yet advised

NIPTmer : rapid k-mer-based software package for detection of fetal aneuploidies

Non-invasive prenatal testing (NIPT) is a recent and rapidly evolving method for detecting genetic lesions, such as aneuploidies, of a fetus. However, there is a need for faster and cheaper laboratory and analysis methods to make NIPT more widely accessible. We have developed a novel software package for detection of fetal aneuploidies from next-generation low-coverage whole genome sequencing data. Our tool - NIPTmer - is based on counting pre-defined per-chromosome sets of unique k-mers from raw sequencing data, and applying linear regression model on the counts. Additionally, the filtering process used for k-mer list creation allows one to take into account the genetic variance in a specific sample, thus reducing the source of uncertainty. The processing time of one sample is less than 10 CPU-minutes on a high-end workstation. NIPTmer was validated on a cohort of 583 NIPT samples and it correctly predicted 37 non-mosaic fetal aneuploidies. NIPTmer has the potential to reduce significantly the time and complexity of NIPT post-sequencing analysis compared to mapping-based methods. For non-commercial users the software package is freely available at http://bioinfo.ut.ee/NIPTMer/.Peer reviewe

Development of a single tube 640-plex genotyping method for detection of nucleic acid variations on microarrays

Detection of DNA sequence variation is critical to biomedical applications, including disease genetic identification, diagnosis and treatment, drug discovery and forensic analysis. Here, we describe an arrayed primer extension-based genotyping method (APEX-2) that allows multiplex (640-plex) DNA amplification and detection of single nucleotide polymorphisms (SNPs) and mutations on microarrays via four-color single-base primer extension. The founding principle of APEX-2 multiplex PCR requires two oligonucleotides per SNP/mutation to generate amplicons containing the position of interest. The same oligonucleotides are then subsequently used as immobilized single-base extension primers on a microarray. The method described here is ideal for SNP or mutation detection analysis, molecular diagnostics and forensic analysis. This robust genetic test has minimal requirements: two primers, two spots on the microarray and a low cost four-color detection system for the targeted site; and provides an advantageous alternative to high-density platforms and low-density detection systems

Copy number variation analysis detects novel candidate genes involved in follicular growth and oocyte maturation in a cohort of premature ovarian failure cases

Can spontaneous premature ovarian failure (POF) patients derived from population-based biobanks reveal the association between copy number variations (CNVs) and POF? CNVs can hamper the functional capacity of ovaries by disrupting key genes and pathways essential for proper ovarian function. POF is defined as the cessation of ovarian function before the age of 40 years. POF is a major reason for female infertility, although its cause remains largely unknown. The current retrospective CNV study included 301 spontaneous POF patients and 3188 control individuals registered between 2003 and 2014 at Estonian Genome Center at the University of Tartu (EGCUT) biobank. DNA samples from 301 spontaneous POF patients were genotyped by Illumina HumanCoreExome (258 samples) and HumanOmniExpress (43 samples) BeadChip arrays. Genotype and phenotype information was drawn from the EGCUT for the 3188 control population samples, previously genotyped with HumanCNV370 and HumanOmniExpress BeadChip arrays. All identified CNVs were subjected to functional enrichment studies for highlighting the POF pathogenesis. Real-time quantitative PCR was used to validate a subset of CNVs. Whole-exome sequencing was performed on six patients carrying hemizygous deletions that encompass genes essential for meiosis or folliculogenesis. Eleven novel microdeletions and microduplications that encompass genes relevant to POF were identified. For example, FMN2 (1q43) and SGOL2 (2q33.1) are essential for meiotic progression, while TBP (6q27), SCARB1 (12q24.31), BNC1 (15q25) and ARFGAP3 (22q13.2) are involved in follicular growth and oocyte maturation. The importance of recently discovered hemizygous microdeletions of meiotic genes SYCE1 (10q26.3) and CPEB1 (15q25.2) in POF patients was also corroborated. This is a descriptive analysis and no functional studies were performed. Anamnestic data obtained from population-based biobank lacked clinical, biological (hormone levels) or ultrasonographical data, and spontaneous POF was predicted retrospectively by excluding known extraovarian causes for premature menopause. The present study, with high number of spontaneous POF cases, provides novel data on associations between the genomic aberrations and premature menopause of ovarian cause and demonstrates that population-based biobanks are powerful source of biological samples and clinical data to reveal novel genetic lesions associated with human reproductive health and disease, including POF. This study was supported by the Estonian Ministry of Education and Research (IUT20-43, IUT20-60, IUT34-16, SF0180027s10 and 9205), Enterprise Estonia (EU30020 and EU48695), Eureka's EUROSTARS programme (NOTED, EU41564), grants from European Union's FP7 Marie Curie Industry-Academia Partnerships and Pathways (IAPP, SARM, |EU324509) and Horizon 2020 innovation programme (WIDENLIFE, 692065), Academy of Finland and the Sigrid Juselius Foundation.Peer reviewe

Genotypic resistance testing in HIV by arrayed primer extension

The analysis of mutations that are associated with the occurrence of drug resistance is important for monitoring the antiretroviral therapy of patients infected with human immunodeficiency virus (HIV). Here, we describe the establishment and successful application of Arrayed Primer Extension (APEX) for genotypic resistance testing in HIV as a rapid and economical alternative to standard sequencing. The assay is based on an array of oligonucleotide primers that are immobilised via their 5′-ends. Upon hybridisation of template DNA, a primer extension reaction is performed in the presence of the four dideoxynucleotides, each labelled with a distinct fluorophore. The inserted label immediately indicates the sequence at the respective position. Any mutation changes the colour pattern. We designed a microarray for the analysis of 26 and 33 codons in the HIV protease and reverse transcriptase, respectively, which are of special interest with respect to drug resistance. The enormous genome variability of HIV represents a big challenge for genotypic resistance tests, which include a hybridisation step, both in terms of specificity and probe numbers. The use of degenerated oligonucleotides resulted in a significant reduction in the number of primers needed. For validation, DNA of 94 and 48 patients that exhibited resistance to inhibitors of HIV protease and reverse transcriptase, respectively, were analysed. The validation included HIV subtype B, prevalent in industrialised countries, as well as non-subtype B samples that are more common elsewhere

Genotyping with a 198 Mutation Arrayed Primer Extension Array for Hereditary Hearing Loss: Assessment of Its Diagnostic Value for Medical Practice

Molecular diagnostic testing of individuals with congenital sensorineural hearing loss typically begins with DNA sequencing of the GJB2 gene. If the cause of the hearing loss is not identified in GJB2, additional testing can be ordered. However, the step-wise analysis of several genes often results in a protracted diagnostic process. The more comprehensive Hereditary Hearing Loss Arrayed Primer Extension microarray enables analysis of 198 mutations across eight genes (GJB2, GJB6, GJB3, GJA1, SLC26A4, SLC26A5, MTRNR1 and MTTS1) in a single test. To evaluate the added diagnostic value of this microarray for our ethnically diverse patient population, we tested 144 individuals with congenital sensorineural hearing loss who were negative for biallelic GJB2 or GJB6 mutations. The array successfully detected all GJB2 changes previously identified in the study group, confirming excellent assay performance. Additional mutations were identified in the SLC26A4, SLC26A5 and MTRNR1 genes of 12/144 individuals (8.3%), four of whom (2.8%) had genotypes consistent with pathogenicity. These results suggest that the current format of this microarray falls short of adding diagnostic value beyond the customary testing of GJB2, perhaps reflecting the array's limitations on the number of mutations included for each gene, but more likely resulting from unknown genetic contributors to this phenotype. We conclude that mutations in other hearing loss associated genes should be incorporated in the array as knowledge of the etiology of hearing loss evolves. Such future modification of the flexible configuration of the Hereditary Hearing Loss Arrayed Primer Extension microarray would improve its impact as a diagnostic tool

Transcriptional and replicational activation functions in the bovine papillomavirus type 1 E2 protein are encoded by different structural determinants.

A set of E2 proteins with mutations in the amino-terminal transactivation domain was made by a scheme called clustered charged-to-alanine scan. These mutant E2 proteins were tested for expression, stability, and compartmentalization in cells and for sequence-specific DNA binding, as well as in functional assays for transcriptional and replicational activation. We identified four groups of mutants. First, mutants K111A, K112A, and E176A were unable to activate replication and transcription because of oligomerization-induced retention of oligomers in the cytoplasm. Second, although fractions of the mutant proteins E74A and D143A/ R172C existed in the oligomeric form, they were localized in the nucleus. Certain fractions of these proteins existed as a dimer able to form a specific complex and activate replication; however, these proteins were inactive in transcriptional activation. Third, mutants R37A and D122A were localized in the nucleus, existed in the dimeric form, supported replication efficiently, and were severely crippled in transcriptional activation. The fourth group of mutants did not differ considerably from the wild-type protein. The activation of transcription by the wild type as well as mutant E2 proteins was dependent on the concentration of input E2 expression vector DNA and had a bell-like shape. We suggest that the reduction of transcriptional activation at higher E2 concentrations, the self-squelching activity, is caused by oligomerization of the E2 transactivator and is one of the mechanisms for the regulation of E2 activity. Our results also show that transcriptional and replicational activation activities are encoded by different determinants in the E2 protein