Chromosome analysis of prenatal samples and products of conception (POC) has conventionally been done by karyotyping (KT). Shortcomings of KT like high turnaround time and culture failure led to technology innovations, such as the bacterial artificial chromosomes (BAC)s-on-Beads (BoBs)-based tests, Prenatal BoBs (prenatal samples) and KaryoLite BoBs (POC samples). In the present study, we validated and evaluated the utility of each test on prenatal, POC and blood samples. Study A (n = 305; 259 prenatal + 46 blood/POC) and Study B (n = 176; 146 POC/chorionic vill + 30 blood/amniotic fluid) samples were analyzed using Prenatal and KaryoLite BoBs kits, respectively. KT, array-based Comparative Genomic Hybridization (arrayCGH) and fluorescence in situ hybridization (FISH) were used for comparison of results. Ability of KaryoLite BoBs to identify ring chromosomes was tested. Prenatal BoBs had zero test failure rate and results of all samples were concordant with KT results. Totally four microdeletions were identified by Prenatal BoBs but not by KT. In Study B, all but two POC samples (one triploid and one tetraploid) were concordant with KT and arrayCGH. Partial chromosomal imbalance detection rate was ~64% and KaryoLite BoBs indicated the presence of a ring chromosome in all four cases. The failure rate of KaryoLite BoBs was 3%. We conclude that Prenatal BoBs (common aneuploidies and nine microdeletions) together with KT constitutes more comprehensive prenatal testing compared to FISH and KT. KaryoLite BoBs for aneuploidies of all chromosomes is highly successful in POC analysis and the ability to indicate presence of ring chromosomes improves its clinical sensitivity. Both tests are robust and could also be used for different specimens.

Digital object identifier (DOI): 10.1111/jog.13920

EML4-ALK gene fusion (inv2(p21p23)) of non-small cell lung cancer (NSCLC) predisposes to tyrosine kinase inhibitor treatment. One of the gold standard diagnostics is the dual color (DC) break-apart (BA) FISH technique, however, the unusual closeness of the involved genes has been suggested to raise likelihood of random co-localization (RCL) of signals. Although this is suspected to decrease sensitivity (often to as low as 40-70%), the exact level and effect of RCL has not been revealed thus far. Signal distances were analyzed to the 0.1 µm precision in more than 25,000 nuclei, via automated high content-image cytometry. Negative and positive controls were created using conventional DC BA-, and inv2(p21p23) mimicking probe-sets, respectively. Average distance between red and green signals was 9.72 pixels (px) (±5.14px) and 3.28px (±2.44px), in positives and negatives, respectively; overlap in distribution being 41%. Specificity and sensitivity of correctly determining ALK status was 97% and 29%, respectively. When investigating inv2(p21p23) with DC BA FISH, specificity is high, but seven out of ten aberrant nuclei are inevitably falsely classified as negative, due to the extreme level of RCL. Together with genetic heterogeneity and dilution effect of non-tumor cells in NSCLC, this immense analytical false negativity is the primary cause behind the often described low diagnostic sensitivity. These results convincingly suggest that if FISH is to remain a gold standard for detecting the therapy relevant inv(2), either a modified evaluation protocol, or a more reliable probe-design should be considered than the current DC BA one.

Digital object identifier (DOI): 10.1002/cyto.a.23489

<h4>BACKGROUND:</h4> <p>Parental balanced reciprocal translocations can result in partial aneuploidies in the offspring due to unbalanced meiotic segregation during gametogenesis. Herein, we report the phenotypic and molecular cytogenetic characterization of a 2 years and 4 months old female child with partial trisomy 7q22 → qter. This is the first such reported case resulting from a parental balanced translocation involving the long arms of chromosomes 7 and 14. The phenotype of the proband was compared with that of previously reported cases of trisomy 7q21 → qter or 7q22 → qter resulting from parental balanced translocations.</p> <h4>CASE PRESENTATION:</h4> <p>The proband was born pre-term to a 34-year-old mother with a history of two first trimester miscarriages and an early infant death. She was referred at the age of 8 months for genetic evaluation due to prenatal and postnatal growth retardation, developmental delay and multiple congenital anomalies. On clinical evaluation, she had craniofacial dysmorphic features such as scaphocephaly, large anterior fontanelle with open posterior fontanelle, prominent occiput, triangular face, high forehead, hypertelorism, down slanting eyes, flat nasal bridge, small nose, low set ears, micro-retrognathia, high arched palate and short neck. Cranial computerized tomography scan showed lateral ventriculomegaly with features of early cerebral atrophy. Conventional cytogenetic analysis showed the karyotype 46,XX,der(14)t(7;14)(q22;q32)mat in the proband due to an unbalanced segregation of a maternal balanced translocation t(7;14)(q22;q32). Fluorescence in-situ hybridization analysis confirmed the partial trisomy 7q22 → qter in the proband with a minimal loss of genetic material on chromosome 14. Single nucleotide polymorphism array further confirmed the duplication on chromosome 7q22.1 → qter and a small terminal deletion on chromosome 14q32.3 → qter.</p> <h4>CONCLUSION:</h4> <p>We report the longest-surviving child with trisomy 7q22 → qter due to a parental balanced translocation between chromosomes 7 and 14. Clinical features observed in the proband were consistent with the consensus phenotype of partial trisomy 7q22 → qter reported in the scientific literature. Early diagnosis of these patients using molecular cytogenetic techniques is important for establishing the precise diagnosis and for making decisions pertaining to the prognostication and management of affected individuals.</p>

Digital object identifier (DOI): 10.1186/s12920-018-0366-6

Chromosomal translocations are hallmarks of various types of cancers and leukemias. However, the molecular mechanisms of chromosome translocations remain largely unknown. The ataxia-telangiectasia mutated (ATM) protein, a DNA damage signaling regulator, facilitates DNA repair to prevent chromosome abnormalities. Previously, we showed that ATM deficiency led to the 11q23 chromosome translocation, the most frequent chromosome abnormalities in secondary leukemia. Here, we show that ARP8, a subunit of the INO80 chromatin remodeling complex, is phosphorylated after etoposide treatment. The etoposide-induced phosphorylation of ARP8 is regulated by ATM and ATR, and attenuates its interaction with INO80. The ATM-regulated phosphorylation of ARP8 reduces the excessive loading of INO80 and RAD51 onto the breakpoint cluster region. These findings suggest that the phosphorylation of ARP8, regulated by ATM, plays an important role in maintaining the fidelity of DNA repair to prevent the etoposide-induced 11q23 abnormalities.

Digital object identifier (DOI): 10.7554/eLife.32222

In neuroblastoma (NB), the most powerful prognostic marker, the MYCN amplification (MNA), occasionally shows intratumoural heterogeneity (ITH), i.e. coexistence of MYCN-amplified and non-MYCN-amplified tumour cell clones, called heterogeneous MNA (hetMNA). Prognostication and therapy allocation are still unsolved issues. The SIOPEN Biology group analysed 99 hetMNA NBs focussing on the prognostic significance of MYCN ITH. Patients &lt;18 months (18 m) showed a better outcome in all stages as compared to older patients (5-year OS in localised stages: &lt;18 m: 0.95 ± 0.04, &gt;18 m: 0.67 ± 0.14, <em>p</em> = 0.011; metastatic: &lt;18 m: 0.76 ± 0.15, &gt;18 m: 0.28 ± 0.09, <em>p</em> = 0.084). The genomic 'background', but not MNA clone sizes, correlated significantly with relapse frequency and OS. No relapses occurred in cases of only numerical chromosomal aberrations. Infiltrated bone marrows and relapse tumour cells mostly displayed no MNA. However, one stage 4s tumour with segmental chromosomal aberrations showed a homogeneous MNA in the relapse. This study provides a rationale for the necessary distinction between heterogeneous and homogeneous MNA. HetMNA tumours have to be evaluated individually, taking age, stage and, most importantly, genomic background into account to avoid unnecessary upgrading of risk/overtreatment, especially in infants, as well as in order to identify tumours prone to developing homogeneous MNA.

Digital object identifier (DOI): 10.1038/s41416-018-0098-6

Fluorescence in situ hybridisation assays designed for del(7q) detection uncover more complex rearrangements in myeloid leukaemia cell lines ABSTRACT Chromosome 7 abnormalities are associated with poor prognosis in myeloid leukaemia. The pathogenetic mechanisms chromosome 7 rearrangements and lead to malignancy are still poorly understood. The use of leukaemia- derived cell lines might be a useful tool to shed some light on these mechanisms. The cytogenetic characterisation of these cell lines is therefore important for the understanding of the genetic alterations leading to the disease. We carried out fluorescence in situ hybridisation (FISH) on three different myeloid leukaemia-derived cell lines (GDM-1, GF-D8 and K562). These were selected on the basis of harbouring rearrangements of chromosome 7. The probes used in these experiments were whole and partial chromosome paints, Multiplex-fluorescence in situ hybridisation (M-FISH) probes as well as locus specific probes for the 7q22, 7q31 and 7q36 regions. Our study confirmed the chromosome 7 abnormalities previously reported in the cell lines GDM-1 and GF-D8. We refined one of the rearrangements of chromosome 7 in the K562 cell line and reported some discrepancies with the data published in earlier reports. With this study, we confirm the importance of using a series of FISH that arise from probes to characterise chromosomal abnormalities in detail, as some rearrangements might go under-detected or mis-interpreted. Moreover, we highlight the importance of monitoring cell lines broadly used in research, as these can lose or acquire characteristics as they evolve in time in different laboratories.

The identification of chromosomal rearrangements is of utmost importance for the diagnosis and classification of specific leukaemia subtypes and therefore has an impact on therapy choices in individual cases. The t(7;12)(q36;p13) is a cryptic rearrangement that is difficult to recognise using conventional cytogenetic methods and is often undetected by reverse transcription polymerase chain reaction due to the absence of a fusion transcript in many cases. Here we present a reliable and easy to use dual colour fluorescence in situ hybridisation assay for the detection of the t(7;12)(q36;p13) rearrangement. A comparison with previous similar work is given and advantages and limitations of this novel approach are discussed.

ABSTRACT: The chromosomal translocation (11;14)(q13;q32) rearranging the locus for cyclin D1 (CCND1) to that of the immunoglobulin heavy chain (IGH) can be found in virtually all cases of mantle cell lymphoma (MCL), while other CCND1 translocations are extremely rare. As CCND1 overexpression and activation is a hallmark of MCL it is regarded as a central biological mechanism in the development and maintenance of this disease.Here we present a patient initially diagnosed with chronic lymphocytic leukemia (CLL) where chromosome banding analysis revealed, among other aberrations, a translocation (11;22)(q13;q11.2). We show by fluorescence in situ hybridization (FISH) analysis that on chromosome 22 the immunoglobulin light chain lambda (IGL) is involved in this cytogenetic aberration. Additionally, we demonstrate the resulting overexpression of CCND1 on the RNA and protein level, thereby consolidating the new diagnosis of a MCL-like B-cell neoplasia. Summing up, we described a rare case of t(11;22)(q13;q11.2) in a MCL-like neoplasia and showed that this aberration leads to an overexpression of CCND1 which is regarded as a key biological feature in MCL. This case underlines the importance of cytogenetic analyses especially in atypical cases of B cell lymphomas.

Tumor samples of 53 patients with t(11;14)-positive mantle cell lymphomas (MCLs) were analyzed by matrix-based comparative genomic hybridization (matrix-CGH) using a dedicated DNA array. In 49 cases, genomic aberrations were identified. In comparison to chromosomal CGH, a 50% higher number of aberrations was found and the high specificity of matrix-CGH was demonstrated by fluorescence in situ hybridization (FISH) analyses. The 11q gains and 13q34 deletions, which have not been described as frequent genomic aberrations in MCL, were identified by matrix-CGH in 15 and 26 cases, respectively. For several genomic aberrations, novel consensus regions were defined: 8p21 (size of the consensus region, 2.4 megabase pairs [Mbp]; candidate genes: TNFRSF10B, TNFRSF10C, TNFRSF10D); 10p13 (2.7 Mbp; BMI1); 11q13 (1.4 Mbp; RELA); 11q13 (5.2 Mbp; CCND1); 13q14 (0.4 Mbp; RFP2, BCMSUN) and 13q34 (6.9 Mbp). In univariate analyses correlating genomic aberrations and clinical course, 8p- and 13q14- deletions were associated with an inferior overall survival. These data provide a basis for further studies focusing on the identification of pathogenetically or clinically relevant genes in MCL.