Molecular Cytogenetic Characterization of the Murine Melanoma Cell Lines S91 Clone M3 and B16-F1 with Variant B16-4A5.

Melanoma is considered to be one of the most aggressive human tumors. Thus, early molecular diagnosis with risk factor stratification could be an efficacious strategy to increase the survival rates in affected patients. Murine cell lines B16-F1, B16-4A5, and S91 clone M3 are the ones most commonly applied in melanoma research. However, genetic peculiarities of these 3 cell lines have not been studied in detail before. Here, we closed this gap by molecular cytogenetic and array-comparative genomic hybridization studies and the translation of the characterized imbalances into the human genome. This study revealed severely rearranged karyotypes with in parts similar imbalances for all 3 cell lines. Interestingly, they involve genes known to play major roles in human melanoma. These are specifically the oncogenes and tumor suppressor genes, being associated with aggressive forms of melanoma. B16-F1, B16-4A5, and S91 clone M3 revealed aberrations which were similarly observed in human eye and skin but not in human uveal melanoma. Thus, they can be considered as model systems for advanced eye and skin melanoma.

Molecular Cytogenomic Characterization of the Murine Breast Cancer Cell Lines C-127I, EMT6/P and TA3 Hauschka.

BACKGROUND: To test and introduce effective and less toxic breast cancer (BC) treatment strategies, animal models, including murine BC cell lines, are considered as perfect platforms. Strikingly, the knowledge on the genetic background of applied BC cell lines is often sparse though urgently necessary for their targeted and really justified application. METHODS: In this study, we performed the first molecular cytogenetic characterization for three murine BC cell lines C-127I, EMT6/P and TA3 Hauschka. Besides fluorescence in situ hybridization-banding, array comparative genomic hybridization was also applied. Thus, overall, an in silico translation for the detected imbalances and chromosomal break events in the murine cell lines to the corresponding homologous imbalances in humans could be provided. The latter enabled a comparison of the murine cell line with human BC cytogenomics. RESULTS: All three BC cell lines showed a rearranged karyotype at different stages of complexity, which can be interpreted carefully as reflectance of more or less advanced tumor stages. CONCLUSIONS: Accordingly, the C-127I cell line would represent the late stage BC while the cell lines EMT6/P and TA3 Hauschka would be models for the premalignant or early BC stage and an early or benign BC, respectively. With this cytogenomic information provided, these cell lines now can be applied really adequately in future research studies.

Genotype-phenotype Correlation of ß-Thalassemia in Croatian Patients: A Specific HBB Gene Mutations.

An analysis of genotype-phenotype correlation was performed for 14 patients with beta-thalassemia who had been registered in Referral Centre for hematology and oncology of the University Hospital Centre, Zagreb, Croatia. HBB gene mutations were determined using a gene-specific Q5 High-Fidelity PCR analysis with direct DNA sequencing of amplified transcripts. Mahidol score index used for classification of thalassemia severity was found to be low for all the patients enrolled in the study, indicating a mild ß-thalassemia phenotype with no signs of disease progression. Most of the patients have already described gene mutations: IVS-II-666 C>T (HBB:c.316-185C>T) and IVS-II-16 G>C (HBB:c.315+16G>C). Each of the aforementioned mutations was found in (11/14; 78,57%) and (10/14; 71,43%) of our patients, respectively. Recently published HBB:c.9T>C mutation was found in 8 of 14 (57,14%) in our study group. IVSII-74 T>G (HBB:c.315+74T>G) is a worldwide mutation found in 6 of 14 (42.86%) of our patients. All these mutations occur among Croatian children with no obvious Indian/Near Eastern/Iranian ancestry. We also identified 7 de novo mutations (c.316-135het_dupT, c.316-133A>G, c.93-54G>A, c.316-68_316-67het_insCGG, c.316-342delA, c.316-312delT, c.316-209delT) of mild severity phenotype according to Mahidol classification score index. We did not find children or adults with thalassemia major severity phenotype.

Molecular cytogenetic characterization of the urethane-induced murine lung cell line LA-4 as a model for human squamous cell lung cancer.

The murine tumor cell line LA-4 (also known as LA4 or LA 4) has been extensively used in ~70 studies from 1975 to present. However, the genetic characteristics have not been comprehensively delineated, apart from a single solid-stain cytogenetic study, which reported an average of 116 chromosomes per cell. LA-4 was created via urethane induction in an A/He mouse and demonstrated characteristic features of lung adenoma cells. In the present study, multicolor banding-based molecular cytogenetics was combined with molecular karyotyping to characterize ploidy, copy number alterations and chromosomal breakpoints of LA-4. A hyper-tetraploid karyotype with 85-93 chromosomes per cell, three distinct (pseudo-) dicentric derivatives, two neocentrics, four unbalanced translocations, two chromosomes with terminal deletions and one chromosome with a balanced inversion were detected. The results were translated into the human genome and a comparison with the literature revealed that LA-4 is well-suited as a murine model for human squamous cell lung cancer.

Cytogenomic characteristics of murine breast cancer cell line JC.

BACKGROUND: Breast cancer (BC), one of the most frequent human tumors, is genetically and histologically heterogeneous. Treatment options can be adapted according to BC subtype. Still, research is necessary to characterize BC biology better and to study potential new treatment options. Murine BC-cell lines can be used as model systems in this respect. RESULTS: Here for the first time murine BC-cell line JC was cytogenomically characterized as being complex rearranged and near-tetraploid. Multicolor banding and array comparative genomic hybridization were applied and the result was in silico translated to the human genome. CONCLUSIONS: Even though being commercially available, cell line JC was yet not much included in BC-research, most likely due to a lack of cytogenomic data. Thus, here comprehensive data is provided on chromosomal aberrations, genomic imbalances and involved breakpoints of JC cell line. Also JC could be characterized as a model for BC of luminal B type, basal-like tumor rather than for luminal A type.

Identification of metastasis-related genes by genomic and transcriptomic studies in murine melanoma.

AIMS: We systematically characterized metastatic murine B16-F10 melanoma, a sub-line derived from murine melanoma B16-F1 cells. MATERIALS AND METHODS: RNA-sequencing and network analyses (Ingenuity Pathway Analysis) were performed to identify novel potential metastasis mechanisms. Chromosomal aberrations were identified by multicolor fluorescence in situ hybridization (mFISH) using all 21 murine whole chromosome painting probes. KEY FINDINGS: Numerous genes were overexpressed in B16-F10 cells, some of which have been already described as being metastasis-linked. Nr5a1/sf1, a known prognostic marker for adrenal tumors, was 177-fold upregulated in B16-F10 cells compared to B16-F1 cells. Hoxb8 was 75-fold upregulated, which was previously associated with gastric cancer progression and metastasis. Ptk7, which is linked with tumorigenesis and metastasis of esophageal squamous carcinoma, was 67-fold upregulated. B16-F10 cells acquired additional chromosomal aberrations compared to B16-F1 cells, including dic(4)(pter->qter:qter->pter), +dic(6;15), +der(10)t(10;?1;16). SIGNIFICANCE: In addition to well-known metastatic genes, numerous novel genes and genomic aberrations were identified, which may serve as targets for treatment in the future. Transcriptomic and genetic analyses in B16-F10 cells unraveled a range of novel metastasis mechanisms, which may also have important implications for future treatment strategies.

Cytogenomic characterization of three murine malignant mesothelioma tumor cell lines.

BACKGROUND: Malignant mesothelioma (MM) is a rare aggressive cancer primary located in pleura and lung. MMs can be divided into biphasic, epithelioid and sarcomatoid subtypes. In majority of cases MMs are induced by asbestos fiber exposure. As latency period after asbestos exposure ranges between ~ 10 and 60 years MMs are mainly observed in elder people. Human MM, being a rare tumor type, lacks detailed cytogenetic data, while molecular genetic studies have been undertaken more frequently. However, murine MM cell lines are also regularly applied to get more insight into MM biology and to test new therapy strategies. RESULTS: Here the murine MM cell lines AB1, AB22 and AC29 were studied by molecular cytogenetics and molecular karyotyping. Interestingly, yet there were no genetic or genomic studies undertaken for these already in 1992 established cell lines. The obtained data on genomic imbalances in these murine cell lines was translated into the human genome as previously reported based on human and murine genomic browsers. CONCLUSIONS: It turned out that all three cell lines showed high similarities in copy number variants as observed typically in human MM. Also, all three cell lines were most similar to human epithelioid MMs, and should be used as models therefore.

Regarding the rights and duties of Clinical Laboratory Geneticists in genetic healthcare systems; results of a survey in over 50 countries.

Specialists of human genetic diagnostics can be divided into four groups: Medical Geneticists (MDG), Genetic Nurses and/or Counsellors (GN/GC), Clinical Laboratory Geneticists (CLG) and Laboratory Genetics Technicians (LGT). While the first two groups are in direct patient contact, the work of the latter two, of equal importance for patient care, are often hidden as they work behind the scenes. Herein the first study on the rights and duties of CLGs is presented. We present the results of a survey performed in 35 European and 18 non-European countries with 100 participating specialists. A national CLG title is available in 60% of European countries, and in 77% of the surveyed European countries a CLG can be the main responsible head of the laboratory performing human genetic tests. However, in only 20% of European countries is a lab-report valid with only a CLGs' signature - even though the report is almost always formulated by the CLG, and an interpretation of the obtained results in a clinical context by the CLG is expected in nearly 90% of European countries. Interestingly, CLGs see patients in 30% of European countries, and are also regularly involved in student education. Overall, the CLG profession includes numerous duties, which are quite similar in all regions of the world. Strikingly, the CLG's rights and responsibilities of leading a lab, or signing a report are regulated differently according to country specific regulations. Overall, the CLG is a well-recognized profession worldwide and often working within a multidisciplinary team of human genetic diagnostics professionals.

Molecular Cytogenetic Characterization Identified the Murine B-Cell Lymphoma Cell Line A-20 as a Model for Sporadic Burkitt's Lymphoma.

Here, we report the first molecular cytogenetic characterization of the BALB/cAnN mouse derived B-cell non-Hodgkin lymphoma (B-cell NHL) cell lines A-20. Even though previously used as a model for testing of, for example, dexametason, up to present, no data in the genetic properties of A-20 were available. The present study closed this gap and provides evidence that A-20 is a model for B-cell NHL subgroup sporadic Burkitt's lymphoma. C-myc oncogene is involved in a translocation and copy number alterations as gain of murine 14q material could be observed. Interestingly, the cell line showed the karyotype 39,X,-X or -Y,t(2;15)(qE5;qD2),del(6)(qB3qC3),del(9)(qA3qA4),dup(14)(qE1qE4) in ~95% of the cells, being exceptionally stable for cell lines being established 38 years ago. Still, ~5% of the cells showed polyploidization followed by chromothripsis. It remains to be determined if this can be observed also in other cell lines, just has not been reported yet, and/or if it is a unique feature of A-20. Overall, finally here, the necessary genetic data to identify A-20 as a model for human sporadic Burkitt's lymphoma are provided.

European registration process for Clinical Laboratory Geneticists in genetic healthcare.

Tremendous progress in genetics and genomics led to a wide range of healthcare providers, genetic tests, and more patients who can benefit from these developments. To guarantee and improve the quality of genetic testing, a unified European-based registration for individuals qualified in biomedicine was realized. Therefore a Europe-wide recognition of the profession 'European registered Clinical Laboratory Geneticist (ErCLG)' based on a syllabus of core competences was established which allows for harmonization in professional education. The 'European Board of Medical Genetics division - Clinical Laboratory Geneticist' provides now since 3 years the possibility to register as an ErCLG. Applicants may be from all European countries and since this year also from outside of Europe. Five subtitles reflect the exact specialty of each ErCLG, who can reregister every 5 years. A previously not possible statistics based on ~300 individuals from 19 countries as holders of an ErCLG title provides interesting insights into the professionals working in human genetics. It could be substantiated that there are around twice as many females than males and that a PhD title was achieved by 80% of registered ErCLGs. Also most ErCLGs are still trained as generalists (66%), followed by such ErCLGs with focus on molecular genetics (23%); the remaining are concentrated either on clinical (6%), tumor (4%) or biochemical genetics (1%). In conclusion, besides MDs and genetic counselors/nurses an EU-wide recognition system for Clinical Laboratory Geneticist has been established, which strengthens the status of specialists working in human genetic diagnostics in Europe and worldwide.

Thoughts about SLC16A2, TSIX and XIST gene like sites in the human genome and a potential role in cellular chromosome counting.

BACKGROUND: Chromosome counting is a process in which cells determine somehow their intrinsic chromosome number(s). The best-studied cellular mechanism that involves chromosome counting is 'chromosome-kissing' and X-chromosome inactivation (XCI) mechanism. It is necessary for the well-known dosage compensation between the genders in mammals to balance the number of active X-chromosomes (Xa) with regard to diploid set of autosomes. At the onset of XCI, two X-chromosomes are coming in close proximity and pair physically by a specific segment denominated X-pairing region (Xpr) that involves the SLC16A2 gene. RESULTS: An Ensembl BLAST search for human and mouse SLC16A2/Slc16a2 homologues revealed, that highly similar sequences can be found at almost each chromosome in the corresponding genomes. Additionally, a BLAST search for SLC16A2/TSIX/XIST (genes responsible for XCI) reveled that "SLC16A2/TSIX/XIST like sequences" cover equally all chromosomes, too. With respect to this we provide following hypotheses. HYPOTHESES: If a single genomic region containing the SLC16A2 gene on X-chromosome is responsible for maintaining "balanced" active copy numbers, it is possible that similar sequences or gene/s have the same function on other chromosomes (autosomes). SLC16A2 like sequences on autosomes could encompass evolutionary older, but functionally active key regions for chromosome counting in early embryogenesis. Also SLC16A2 like sequence on autosomes could be involved in inappropriate chromosomes pairing and, thereby be involved in aneuploidy formation during embryogenesis and cancer development. Also, "SLC16A2/TSIX/XIST gene like sequence combinations" covering the whole genome, could be important for the determination of X:autosome ratio in cells and chromosome counting. CONCLUSIONS: SLC16A2 and/or SLC16A2/TSIX/XIST like sequence dispersed across autosomes and X-chromosome(s) could serve as bases for a counting mechanism to determine X:autosome ratio and could potentially be a mechanism by which a cell also counts its autosomes. It could also be that such specific genomic regions have the same function for each specific autosome. As errors during the obviously existing process of chromosome counting are one if not the major origin of germline/somatic aneuploidy the here presented hypotheses should further elaborated and experimentally tested.

Complex intrachromosomal rearrangement in 1q leading to 1q32.2 microdeletion: a potential role of SRGAP2 in the gyrification of cerebral cortex.

BACKGROUND: Van der Woude syndrome (MIM: 119300, VWS) is a dominantly inherited and the most common orofacial clefting syndrome; it accounts for ~2 % of all cleft lip and palate cases. Intellectual disability (ID) is characterized by significant limitations, both in intellectual functioning (cognitive deficit) and in adaptive behavior as expressed in conceptual, social and practical adaptive skills. Karyotyping has been the first standard test for the detection of genetic imbalance in patients with ID for more than 35 years. Advances in genetic diagnosis have laid chromosomal microarrays (CMA) as a new standard and first first-line test for diagnosis of patients with ID, as well as other conditions, such as autism spectrum disorders or multiple congenital anomalies. CASE PRESENTATION: The present case was initially studied due to unexplained cognitive deficit. Physical examination at the age of 18 years revealed cleft palate, lower lip pits and hypodontia, accompanied with other dysmorphic features and absence of speech. Brain MRI uncovered significantly reduced overall volume of gray matter and cortical gyrification. Banding cytogenetics revealed an indistinct intrachromosomal rearrangement in the long arm of one chromosome 1, and subsequent microarray analyses identified a 5.56 Mb deletion in 1q32.1-1q32.3, encompassing 52 genes; included were the entire IRF6 gene (whose mutations/deletions underlay VWS) and SRGAP2, a gene with an important role in neuronal migration during development of cerebral cortex. Besides, a duplication in 3q26.32 (1.9 Mb in size) comprising TBL1XR1 gene was identified. Multicolor banding for chromosome 1 and molecular cytogenetics applying a battery of locus-specific probes covering 1q32.1 to 1q44 characterized a four breakpoint-insertional-rearrangement-event, resulting in 1q32.1-1q32.3 deletion. CONCLUSIONS: Considering that the human-specific three-fold segmental duplication of SRGAP2 gene evolutionary corresponds to the beginning of neocortical expansion, we hypothesize that aberrations in SRGAP2 are strong candidates underlying specific brain abnormalities, namely reduced volume of grey matter and reduced gyrification.

A novel IGH@ gene rearrangement associated with CDKN2A/B deletion in young adult B-cell acute lymphoblastic leukemia.

Acquired copy number changes are common in acute leukemia. They are reported as recurrent amplifications or deletions (del), and may be indicative of involvement of oncogenes or tumor suppressor genes in acquired disease, as well as serving as potential biomarkers for prognosis or as targets for molecular therapy. The present study reported a gain of copy number of 14q13 to 14q32, leading to immunoglobulin heavy chain locus splitting in a young adult female. To the best of our knowledge, this rearrangement has not been previously reported in B-cell acute lymphoblastic leukemia (ALL). Low resolution banding cytogenetics performed at the time of diagnosis revealed a normal karyotype. However, retrospective application of fluorescence in situ hybridization (FISH) banding and locus-specific FISH probes, as well as multiplex ligation-dependent probe amplification and high resolution array-comparative genomic hybridization, revealed previously hidden aberrations. Overall, a karyotype of 46, XX, del(9) (p21.3 p21.3),derivative(14) (pter-> q32.33:: q32.33-> q13 ::q32.33-> qter) was determined. The patient was treated according to the Polish Adult Leukemia Group protocol and achieved complete remission. The results of the present study indicate that a favorable prognosis is associated with these aberrations when the aforementioned treatment is administered.

Isochromosome 17q in Chronic Lymphocytic Leukemia.

In chronic lymphocytic leukemia (CLL), presence of acquired cytogenetic abnormalities may help to estimate prognosis. However, deletion of TP53 gene, which is associated with an aggressive course of the disease and poor prognosis along with a lack of response to treatment, is one of the alterations which may escape cytogenetic diagnoses in CLL. Thus, other techniques have emerged such as interphase fluorescence in situ hybridization (iFISH). Deletion of TP53 may but must not go together with the formation of an isochromosome i(17q); surprisingly this subgroup of patients was not in the focus of CLL studies yet. This study was about if presence of i(17q) could be indicative for a new subgroup in CLL with more adverse prognosis. As a result, TP53 deletion was detected in 18 out of 150 (12%) here studied CLL cases. Six of those cases (~33%) had the TP53 deletion accompanied by an i(17q). Interestingly, the cases with i(17q) showed a tendency towards more associated chromosomal aberrations. These findings may be the bases for follow-up studies in CLL patients with TP53 deletion with and without i(17q); it may be suggested that the i(17q) presents an even more adverse prognostic marker than TP53 deletion alone.

Association of new deletion/duplication region at chromosome 1p21 with intellectual disability, severe speech deficit and autism spectrum disorder-like behavior: an all-in approach to solving the DPYD enigma.

We describe an as yet unreported neocentric small supernumerary marker chromosome (sSMC) derived from chromosome 1p21.3p21.2. It was present in 80% of the lymphocytes in a male patient with intellectual disability, severe speech deficit, mild dysmorphic features, and hyperactivity with elements of autism spectrum disorder (ASD). Several important neurodevelopmental genes are affected by the 3.56 Mb copy number gain of 1p21.3p21.2, which may be considered reciprocal in gene content to the recently recognized 1p21.3 microdeletion syndrome. Both 1p21.3 deletions and the presented duplication display overlapping symptoms, fitting the same disorder category. Contribution of coding and non-coding genes to the phenotype is discussed in the light of cellular and intercellular homeostasis disequilibrium. In line with this the presented 1p21.3p21.2 copy number gain correlated to 1p21.3 microdeletion syndrome verifies the hypothesis of a cumulative effect of the number of deregulated genes - homeostasis disequilibrium leading to overlapping phenotypes between microdeletion and microduplication syndromes. Although miR-137 appears to be the major player in the 1p21.3p21.2 region, deregulation of the DPYD (dihydropyrimidine dehydrogenase) gene may potentially affect neighboring genes underlying the overlapping symptoms present in both the copy number loss and copy number gain of 1p21. Namely, the all-in approach revealed that DPYD is a complex gene whose expression is epigenetically regulated by long non-coding RNAs (lncRNAs) within the locus. Furthermore, the long interspersed nuclear element-1 (LINE-1) L1MC1 transposon inserted in DPYD intronic transcript 1 (DPYD-IT1) lncRNA with its parasites, TcMAR-Tigger5b and pair of Alu repeats appears to be the "weakest link" within the DPYD gene liable to break. Identification of the precise mechanism through which DPYD is epigenetically regulated, and underlying reasons why exactly the break (FRA1E) happens, will consequently pave the way toward preventing severe toxicity to the antineoplastic drug 5-fluorouracil (5-FU) and development of the causative therapy for the dihydropyrimidine dehydrogenase deficiency.

MLLT10 and IL3 rearrangement together with a complex four-way translocation and trisomy 4 in a patient with early T-cell precursor acute lymphoblastic leukemia: A case report.

Cytogenetic classification of acute lymphoblastic leukemia (ALL) is primarily based on numerical and structural chromosomal abnormalities. In T-cell ALL (T-ALL), chromosomal rearrangements are identified in up to 70% of the patients while the remaining patients show a normal karyotype. In the present study, a 16-year-old male was diagnosed with T-precursor cell ALL and a normal karyotype after standard GTG-banding, was studied retrospectively (>10 years after diagnosis) in frame of a research project by molecular approaches. In addition to molecular cytogenetics, multiplex ligation-dependent probe amplification (MLPA) and high resolution array-comparative genomic hybridization (aCGH) were also applied. Thus, the following yet unrecognized balanced chromosomal aberrations were detected: der(3)t(3;5)(p23;q31.1), der(5)t(3;5)(p23;q35.3), der(5)t(5;10)(q31.1;p12.3) and der(10)t(5;10)(q35.3;p12.3). The oncogene MLLT10 was involved in this rearrangement as was the IL3 gene; in addition, trisomy 4 was present. All of these clonal aberrations were found in 40% of the cells. Even if this complex karyotype would have been identified at the time of diagnosis, most likely no other protocol of anticancer therapy (ALL-BFM 95) would have been applied. Three months after the end of a successful 2-year treatment, the patient suffered from isolated bone marrow relapse and died of sepsis during ALL-REZ-BFM protocol treatment.

Novel Cryptic Rearrangements in Adult B-Cell Precursor Acute Lymphoblastic Leukemia Involving the MLL Gene.

MLL (mixed-lineage-leukemia) gene rearrangements are typical for acute leukemia and are associated with an aggressive course of disease, with a worse outcome than comparable case, and thus require intensified treatment. Here we describe a 69-year-old female with adult B cell precursor acute lymphoblastic leukemia (BCP-ALL) with hyperleukocytosis and immunophenotype CD10- and CD19+ with cryptic MLL rearrangements. G-banding at the time of diagnosis showed a normal karyotype: 46,XX. Molecular cytogenetics using multitude multicolor banding (mMCB) revealed a complex rearrangement of the two copies of chromosome 11. However, a locus-specific probe additionally identified that the MLL gene at 11q23.3 was disrupted, and that the 5' region was inserted into the chromosomal sub-band 4q21; thus the aberration involved three chromosomes and five break events. Unfortunately, the patient died six months after the initial diagnosis from serious infections and severe complications. Overall, the present findings confirm that, by far not all MLL aberrations are seen by routine chromosome banding techniques and that fluorescence in situ hybridization (FISH) should be regarded as standard tool to access MLL rearrangements in patients with BCP-ALL.

High rates of submicroscopic aberrations in karyotypically normal acute lymphoblastic leukemia.

BACKGROUND: Acute lymphoblastic leukemia (ALL) is not a single uniform disease. It consists of several subgroups with different cytogenetic and molecular genetic aberrations, clinical presentations and outcomes. Banding cytogenetics plays a pivotal role in the detection of recurrent chromosomal rearrangements and is the starting point of genetic analysis in ALL, still. Nowadays, molecular (cyto)genetic tools provide substantially to identify previously non-detectable, so-called cryptic chromosomal aberrations in ALL. However, ALL according to banding cytogenetics with normal karyotype - in short cytogenetically normal ALL (CN-ALL) - represent up to ~50 % of all new diagnosed ALL cases. The overall goal of this study was to identify and characterize the rate of cryptic alterations in CN-ALL and to rule out if one single routine approach may be sufficient to detect most of the cryptic alterations present. RESULTS: Sixty-one ALL patients with CN-ALL were introduced in this study. All of them underwent high resolution fluorescence in situ hybridization (FISH) analysis. Also DNA could be extracted from 34 ALL samples. These DNA-samples were studied using a commercially available MLPA (multiplex ligation-dependent probe amplification) probe set directed against 37 loci in hematological malignancies and/or array-comparative genomic hybridization (aCGH). Chromosomal aberrations were detected in 21 of 61 samples (~34 %) applying FISH approaches: structural abnormalities were present in 15 cases and even numerical ones were identified in 6 cases. Applying molecular approaches copy number alterations (CNAs) were detected in 27/34 samples. Overall, 126 CNAs were identified and only 34 of them were detectable by MLPA (~27 %). Loss of CNs was identified in ~80 % while gain of CNs was present in ~20 % of the 126 CNAs. A maximum of 13 aberrations was detected per case; however, only one aberration per case was found in 8 of all in detail studied 34 cases. Of special interest among the detected CNAs are the following new findings: del(15)(q26.1q26.1) including CHD2 gene was found in 20 % of the studied ALL cases, dup(18)(q21.2q21.2) with the DCC gene was present in 9 % of the cases, and the CDK6 gene in 7q21.2 was deleted in 12 % of the here in detail studied ALL cases. CONCLUSIONS: In conclusion, high resolution molecular cytogenetic tools and molecular approaches like MLPA and aCGH need to be combined in a cost-efficient way, to identify disease and progression causing alterations in ALL, as majority of them are cryptic in banding cytogenetic analyses.

Comprehensive chronic lymphocytic leukemia diagnostics by combined multiplex ligation dependent probe amplification (MLPA) and interphase fluorescence in situ hybridization (iFISH).

BACKGROUND: Banding-karyotyping and metaphase-directed-fluorescence-in-situhybridization (FISH) may be hampered by low mitotic index in leukemia. Interphase FISH (iFISH) is a way out here, however, testing many probes at the same time is protracted and expensive. Here multiplex-ligation-dependent-probe-amplification (MLPA) was used retrospectively in chronic lymphocytic leukemia (CLL) samples initially studied by banding cytogenetics and iFISH. Detection rates of iFISH and MLPA were compared and thus a cost-efficient scheme for routine diagnostics is proposed. RESULTS: Banding cytogenetics was done successfully in 67/85 samples. DNA was extracted from all 85 CLL samples. A commercially available MLPA probe set directed against 37 loci prone to be affected in hematological malignancies was applied. Besides, routine iFISH was done by commercially available probes for following regions: 11q22.3, 12p11.2-q11.1, 13q14.3, 13q34, 14q32.33 and 17p13.1. MLPA results were substantiated by iFISH using corresponding locus-specific probes. Aberrations were detected in 67 of 85 samples (~79%) applying banding cytogenetics, iFISH and MLPA. A maximum of 8 aberrations was detected per sample; however, one aberration per sample was found most frequently. Overall 163 aberrations were identified. 15 of those (~9%) were exclusively detected by banding cytogenetics, 95 were found by MLPA (~58%) and 100 (~61%) by routine iFISH. MLPA was not able to distinguish reliably between mono- and biallelic del(13)(q14.3q14.3), which could be easily identified as well as quantified by routine iFISH. Also iFISH was superior to MLPA in samples with low tumor cell load. On the other hand MLPA detected additional aberrations in 22 samples, two of them being without any findings after routine iFISH. CONCLUSIONS: Both MLPA and routine iFISH have comparable detection rates for aberrations being typically present in CLL. As MLPA can detect also rare chromosomal aberrations it should be used as an initial test if routine cytogenetics is not possible or non-informative. Still iFISH should be used additionally to distinguish mono- from biallelic deletions and also to determine rate of mosaicism for 13q14.2 to 13q14.3. In case MLPA is negative the corresponding CLL samples should be tested at least by iFISH using the standard probe set to.