PubMed Health⌕ Search

Biomedical subjects

Reiner Siebert

Publications and source records attributed to Reiner Siebert.

71 records · Page 4Linked to original sources
PubMed2003

Molecular characterization of BCL6 breakpoints in primary diffuse large B-cell lymphomas of the central nervous system identifies GAPD as novel translocation partner.

Primary central nervous system lymphomas (PCNSL) constitute diffuse large B-cell lymphomas arising in and remaining confined to the brain. Little information is available on cytogenetic changes in PCNSL, and recurrent chromosomal translocations have not yet been identified. Fluorescence in situ hybridization (FISH) of a series of 13 PCNSL from immunocompetent patients revealed 3 cases with signal patterns of a BCL6-specific probe suggesting a breakpoint in this oncogene locus in chromosome band 3q27. Here, we describe cloning of the translocation breakpoints by long-distance inverse polymerase chain reaction (LDI-PCR) in 2 of these tumors. Both breakpoints affected the first intron of BCL6. In one PCNSL, the HSPCA (HSP90A) gene in 14q32.31 was identified as BCL6 partner. In the second lymphoma, the gene encoding glyceraldehyde-3-phosphate dehydrogenase (GAPD) on 12p13.31 was detected as a hitherto unknown partner of BCL6. Our results suggest translocation-mediated BCL6 oncogene activation as a so far unknown pathogenetically relevant mechanism in PCNSL.

Aged↗
PubMed2002

Clinicopathologic correlations of genomic gains and losses in follicular lymphoma.

PURPOSE: To evaluate the clinical relevance of genomic aberrations in follicular lymphomas (FLs). PATIENTS AND METHODS: In this study, we analyzed 124 biopsy samples of patients with FL using comparative genomic hybridization. RESULTS: In 87 cases (70%), genomic imbalances were detectable. The most frequent aberrations were gains of chromosome arms 7p (21 patients), 7q (21 patients), Xp (16 patients), 12q (15 patients), and 18q (14 patients) as well as losses on 6q (21 patients). Grades 2 and 3 according to the World Health Organization classification correlated with a more complex karyotype (P <.0001). In a subset of 82 patients, a comprehensive clinical data set was available. In a multivariate analysis including all clinical risk factors of the International Prognostic Index as well as genomic aberrations, the loss of material on chromosomal bands 6q25q27 was the strongest predictor of a shorter survival (P =.0001; hazard ratio, 6.5), followed by elevated serum lactate dehydrogenase level (P =.0009; hazard ratio, 4.9), the presence of more than one extranodal manifestation (P =.017; hazard ratio, 4.2), and age greater than 60 years (P =.022; hazard ratio, 2.6). CONCLUSION: These data indicate that genomic aberrations may contribute significantly to risk assessment in patients with FL, the majority of whom are included in low-risk groups using established clinical prognostic scores.

Adult↗
PubMed2002

Frequent occurrence of BCL6 rearrangements in nodular lymphocyte predominance Hodgkin lymphoma but not in classical Hodgkin lymphoma.

We studied the genomic status of BCL6 in 23 cases of nodular lymphocyte predominance Hodgkin lymphoma (NLPHL) and 40 cases of classical Hodgkin lymphoma (cHL), using dual-color interphase fluorescence in situ hybridization (FISH). The BCL6 rearrangement was identified in 48% of NLPHL cases and was not detected in cHL cases. As a confirmation, sequential or simultaneous immunohistochemistry (IHC) and FISH using CD20 or BCL6 antibodies and BCL6 DNA probes was performed in 8 NLPHL cases. The BCL6-associated translocations, t(3;22)(q27;q11), t(3;7)(q27;p12), and the most probable t(3;9)(q27;p13), were identified in 3 cases. A consistent expression of BCL6 protein in popcorn cells with the highest number of intensely stained cells in cases with a genomic BCL6 rearrangement was shown by IHC. These findings support the hypothesis of a germinal center B cell-derived origin of NLPHL, indicate a significant role of BCL6 in the pathogenesis of NLPHL, and provide further evidence of the genetic diversity underlying the pathogenesis of NLPHL and cHL.

B-Lymphocytes↗
PubMed2002

Mutations in the LGI1/Epitempin gene on 10q24 cause autosomal dominant lateral temporal epilepsy.

Autosomal dominant lateral temporal epilepsy (EPT; OMIM 600512) is a form of epilepsy characterized by partial seizures, usually preceded by auditory signs. The gene for this disorder has been mapped by linkage studies to chromosomal region 10q24. Here we show that mutations in the LGI1 gene segregate with EPT in two families affected by this disorder. Both mutations introduce premature stop codons and thus prevent the production of the full-length protein from the affected allele. By immunohistochemical studies, we demonstrate that the LGI1 protein, which contains several leucine-rich repeats, is expressed ubiquitously in the neuronal cell compartment of the brain. Moreover, we provide evidence for genetic heterogeneity within this disorder, since several other families with a phenotype consistent with this type of epilepsy lack mutations in the LGI1 gene.

Alternative Splicing↗
PubMed2002

Interphase FISH assays for the detection of translocations with breakpoints in immunoglobulin light chain loci.

Many B-cell malignancies bear chromosomal translocations juxtaposing immunoglobulin (IG) genes with oncogenes, resulting in deregulated expression of the latter. Translocations affecting the IG heavy chain (IGH) locus in chromosomal region 14q32 are most prevalent. However, variant translocations involving the IG kappa (IGK) locus in 2p12 or the IG lambda (IGL) locus in 22q11 occur recurrently in B-cell neoplasias. No routine methods for the detection of all breakpoints involving IG light chain loci independently of the translocation partner have been described. For this reason, we have designed 2 novel interphase fluorescence in situ hybridization (FISH) assays using differentially labeled probes flanking the IGK and IGL locus, respectively. Based on extensive control studies, the diagnostic thresholds for the detection of breakpoints were set at 0.3% for IGK and 1.4% for IGL. Fifteen cases of B-cell malignancies with cytogenetically detectable chromosomal abnormalities in 2p11-14 were investigated with the FISH assay for IGK. Breakpoints affecting the IGK locus were detected in 7 cases including all 4 variant Burkitt's translocations t(2;8)(p12;q24) and a variant BCL2-associated translocation t(2;18)(p12;q21). Other translocation partners were chromosome bands 7q21 and 16q24. Ten cases with abnormalities in 22q11-12 were investigated with the FISH assay for IGL. Breakpoints in the IGL locus were diagnosed in 7 cases including both variant Burkitt's translocations t(8;22)(q24;q11) and a t(3;22)(q27;q11) involving the BCL6 locus. Other translocation partners were 2p13-14, 4q13 and 16p12. Our results show that these FISH assays provide flexible, simple and reliable tools in the diagnosis and characterization of genetic changes in B-cell malignancies.

Adolescent↗
PubMed2002

Classical Hodgkin lymphoma is characterized by recurrent copy number gains of the short arm of chromosome 2.

Hodgkin- and Reed-Sternberg (HRS) cells microdissected from 41 classical Hodgkin lymphomas (cHL) of 40 patients comprising 8 lymphocyte-rich (cHL-LR), 16 nodular sclerosis (cHL-NS), 15 mixed-cellularity (cHL-MC), and 2 lymphocyte-depletion (cHL-LD) subtypes were analyzed by comparative genomic hybridization for recurrently imbalanced chromosomal subregions. Chromosomal gains most frequently involved chromosome 2p (54%), 12q (37%), 17p (27%), 9p and 16p (24% each), and 17q and 20q (20% each), whereas losses primarily affected chromosome 13q (22%). Using fluorescence in situ hybridization, amplification of the REL oncogene was demonstrated within a distinct 2p15-p16 amplicon. The high frequency of 2p overrepresentations including REL, particularly in cHL-NS (88%), suggests that an alternative mechanism of constitutive activation of nuclear factor NF-kappaB is a hallmark of HRS cells. Hierarchical cluster analysis of chromosomal imbalances revealed a closer relationship among cHL-NS than other subtypes. Furthermore, there is a tendency for different subtypes of cHL-MC tumors characterized by different ages at the time of tumor onset and gain of chromosome 17p. The imbalance pattern of cHL subtypes suggests that different molecular pathways are activated, with REL or other genes on chromosomal band 2p15-p16 playing a fundamental role in the pathogenesis of classical Hodgkin lymphoma.

Adolescent↗
PubMed2002

Recurrent involvement of the REL and BCL11A loci in classical Hodgkin lymphoma.

Comparative genomic hybridization studies have shown gains in chromosome region 2p as the most common imbalance in classical Hodgkin lymphoma (cHL). The minimal region of gain contained 2 candidate oncogenes, REL and BCL11A. This study examined the involvement of REL and BCL11A loci in 44 primary cases of cHL by combined immunophenotyping and interphase cytogenetics (FICTION). A median 2p13 copy number above the tetraploid range was detected in 24 (55%) cases. Adjustment for centromere 2 copy number indicated gains of 2p13 in 11 of 31 cHLs (35%) with 8 (26%) high-level amplifications. One cHL displayed selective amplification of the REL locus not affecting BCL11A; another case studied by FICTION and a cHL with cytogenetic 2p change investigated by fluorescence in situ hybridization showed signal patterns suggesting breakpoints in the region spanned by the REL probe. These data indicate that REL rather than BCL11A may be the target of the 2p13 alterations in cHL.

Adolescent↗
PubMed2002

Mutation detection and physical mapping of the CD11 gene cluster in association with inflammatory bowel disease.

A genetic component in the etiology of inflammatory bowel disease (IBD) has clearly been demonstrated by epidemiological and genetic linkage studies. Linkage to IBD on proximal Chromosome (Chr) 16p is well established and replicated. A stratification experiment showed that the recent identification of a disease gene on the q arm does not interfere with the approach on the p arm, and the linkage peak is still significant. Here we present a candidate gene study of the alpha integrins (CD11A-D) on Chr 16. The alpha integrins play a key role in inflammatory processes, including leukocyte adhesion and migration. Their genes are located on the p arm of Chr 16, and therefore represent excellent positional and functional candidates. Since the assignment of the CD11 genes in the genome was not clear, we performed physical, radiation hybrid, and fluorescent in situ hybridization mapping of the gene family. All CD11 genes map on Chr 16p11-12. CD11B-D are arranged in a gene cluster within 300 kb and CD11A is located about 2.5 Mb telomeric. Thirteen new single nucleotide polymorphisms (SNPs) and eight SNPs from databases were identified through full-length sequencing. Case-control statistics demonstrated an association lead in the CD11 gene cluster, which was not confirmed in further family based association/linkage analyses using single markers and haplotypes. It is unlikely that the CD11 genes play an important role in the pathogenesis of IBD. The marginally significant results could indicate a disease gene in the vicinity of the gene cluster.

CD11 Antigens↗
PubMed2002

Multicolor-FICTION: expanding the possibilities of combined morphologic, immunophenotypic, and genetic single cell analyses.

Phenotypic and genotypic analyses of cells are increasingly essential for understanding pathogenetic mechanisms as well as for diagnosing and classifying malignancies and other diseases. We report a novel multicolor approach based on the FICTION (fluorescence immunophenotyping and interphase cytogenetics as a tool for the investigation of neoplasms) technique, which enables the simultaneous detection of morphological, immunophenotypic, and genetic characteristics of single cells. As prerequisite, multicolor interphase fluorescence in situ hybridization assays for B-cell non-Hodgkin's lymphoma and anaplastic large-cell lymphoma have been developed. These assays allow the simultaneous detection of the most frequent primary chromosomal aberrations in these neoplasms, such as t(8;14), t(11;14), t(14;18), and t(3;14), and the various rearrangements of the ALK gene, respectively. To establish the multicolor FICTION technique, these assays were combined with the immunophenotypic detection of lineage- or tumor-specific antigens, namely CD20 and ALK, respectively. For evaluation of multicolor FICTION experiments, image acquisition was performed by automatic sequential capturing of multiple focal planes. Thus, three-dimensional information was obtained. The multicolor FICTION assays were applied to well-characterized lymphoma samples, proving the performance, validity, and diagnostic power of the technique. Future multicolor FICTION applications include the detection of preneoplastic lesions, early stage and minimal residual diseases, or micrometastases.

Adult↗
PubMed2002

The novel EPTP repeat defines a superfamily of proteins implicated in epileptic disorders.

Recent studies suggest that mutations in the LGI1/Epitempin gene cause autosomal dominant lateral temporal epilepsy. This gene encodes a protein of unknown function, which we postulate is secreted. The LGI1 protein has leucine-rich repeats in the N-terminal sequence and a tandem repeat (which we named EPTP) in its C-terminal region. A redefinition of the C-terminal repeat and the application of sensitive sequence analysis methods enabled us to define a new superfamily of proteins carrying varying numbers of the novel EPTP repeats in combination with various extracellular domains. Genes encoding proteins of this family are located in genomic regions associated with epilepsy and other neurological disorders.

Amino Acid Sequence↗
PubMed2002

The novel human beta-defensin-3 is widely expressed in oral tissues.

The purpose of this study was to investigate the expression of human beta-defensins (hBD), especially of the recently discovered hBD-3, in oral tissues by reverse-transcription polymerase chain reaction (RT-PCR). Primary oral keratinocytes (n = 3) and fibroblasts (n = 3), 64 non-inflamed and 40 inflamed oral tissue samples, and 10 samples of salivary glands, were examined. The transcripts for hBD-3 (61/64), as well as for hBD-1 (64/64) and hBD-2 (54/64), were found to be widely expressed in non-inflamed oral tissues. In contrast, only 23, 22 and 24 of the 40 inflamed tissues showed detectable hBD-1, -2 and -3 transcripts, respectively. In salivary glands, mRNA expression was constitutive for hBD-1, frequent for hBD-2 (9/10), and infrequent for hBD-3 (4/10). Oral keratinocytes, but not fibroblasts, contained transcripts for all beta-defensins, suggesting that the novel hBD-3 is also produced in the epithelial compartment of oral tissues. The results indicate an important role for the novel hBD-3, as well as for hBD-1 and hBD-2, in the innate oral epithelial host defense.

Anti-Bacterial Agents↗
PubMed2002

An unbalanced translocation involving chromosome 14 is the probable cause for loss of potentially functional rearranged immunoglobulin heavy chain genes in the Epstein-Barr virus-positive Hodgkin's lymphoma-derived cell line L591.

In the vast majority of cases, Hodgkin-Reed Sternberg (H-RS) cells, the malignant cells in Hodgkin's lymphoma (HL), are derived from germinal centre B cells. In some cases, somatic mutations within the rearranged immunoglobulin heavy (IgH) chain genes were detected, rendering potentially functional gene rearrangements non-functional. In these H-RS cells the expression of high-affinity B-cell receptors (BCR) was prevented. As in other cases only one non-productive IgH chain gene rearrangement was amplified from H-RS cells, it was speculated whether, in these cases, the functionally rearranged IgH chain genes were lost. An alternative explanation might be that the rearranged genes could not be amplified owing to a high load of somatic mutations within the primer binding sites. Here, we showed that, in the HL-derived Epstein-Barr virus (EBV)-positive cell line L591, only one non-functional somatically mutated IgH gene rearrangement could be detected. The other potentially functional IgH gene rearrangement was lost as a result of an unbalanced translocation affecting the long arm of chromosome 14. Moreover, L591 cells express the EBV latent membrane proteins LMP1 and LMP2A, which might have contributed to the 'escape' of these cells from apoptosis within the germinal centre. We conclude that, apart from the introduction of 'crippling mutations' into the rearranged VDJ genes rearrangement, deletions of the IGH locus may be regarded as another mechanism to prevent the expression of a BCR in H-RS cells.

Amino Acid Sequence↗
PubMed2002

FCGR3 variants and expression of human neutrophil antigen-1a, -1b, and -1c in the populations of northern Germany and Uganda.

BACKGROUND: Human neutrophil antigen-1c (HNA-1c) (SH) has been described as the third alloantigen of the Fc receptor type IIIb (FcgammaRIIIb) for IgG beside the known alloantigens HNA-1a (NA1) and HNA-1b (NA2). Controversy exists on the assignment of the HNA-1c coding gene to the FCGR3B locus and on a possible linkage between the HNA-1c and HNA-1a coding genes. STUDY DESIGN AND METHODS: Two hundred sixty northern German blood donors and 43 individuals from Uganda were typed for FCGR3B*1 (NA1), FCGR3B*2 (NA2), and FCGR3B*3 (SH) by allele-specific PCR. In a subset of FCGR3B*3-positive probands, PCR-amplified FCGR3 fragments were subcloned and sequenced. Transmission of FCGR3B*3 was analyzed in family studies. A possible correlation with the FcgammaRIIIb alloantigen expression was investigated by flow cytometry. RESULTS: In the northern German population, FCGR3B*3 was found exclusively in individuals carrying FCGR3B*1 independent of the existence of FCGR3B*2 at a frequency of 5 percent. In the individuals from Uganda, each possible combination of FCGR3B*1, FCGR3B*2, and FCGR3B*3 was detected. FCGR3B*3 frequency was 34.9 percent. Within both populations, some individuals carried each of the three genotypes. DNA sequencing revealed new FCGR3 variants caused by single nucleotide exchanges at the typical polymorphic positions. In one individual, six different FCGR3 variants were detected. CONCLUSION: The coincidence of the three known FCGR3B alleles varies within the population of Germany and Uganda. Three simultaneous FCGR3B forms may be explained by two gene loci, but the basis of the high number of different variants in some individuals still remains unclear. Possible explanations may be a hypermutation mechanism or a number of FCGR3 higher than expected hitherto.

Alleles↗
PubMed2002

Central precocious puberty in girls with Williams syndrome.

We report an estimated prevalence of precocious puberty of 1 in 5 to 6 girls with Williams syndrome (18.3%). Mean menarcheal age of 86 girls with Williams syndrome was 11.5 +/- 1.7 (+/-SD) years. Distribution of menarcheal age was significantly different from that in normal girls (12.9 +/- 1.1 years; n = 759).

Adolescent↗
PubMed2002

Interphase cytogenetic analysis of lymphoma-associated chromosomal breakpoints in primary diffuse large B-cell lymphomas of the central nervous system.

Primary central nervous system lymphomas (PCNSLs) are germinal center-derived diffuse large B-cell lymphomas (DLBCLs) arising in and remaining confined to the brain, the pathogenesis of which is poorly understood. We investigated 13 PCNSLs from immunocompetent patients by means of interphase cytogenetics on cryopreserved cells derived from stereotactic biopsies. Interphase fluorescence in situ hybridization (FISH) was performed for the detection of structural alterations affecting the IGH (14q32), IGK (2p12), IGL (22q11), BCL6 (3q27), MYC (8q24), CCND1 (11q13), MLT, and BCL2 (both 18q21) loci. Signal constellations indicating breakpoints within the IGH and IGK locus were detected in 5 and 1 PCNSLs, respectively. There was no evidence for a t(8;14), t(11;14), or t(14;18) in this series of tumors. Breakpoints in the BCL6 locus were observed in 3 of the 13 cases, and nuclear Bcl-6 protein expression was detected in 6 of 9 PCNSLs, including those with genomic alterations of the encoding locus. Gains of 18q21 represented the most frequent imbalances present in more than one third of all cases. Interestingly, these gains included the MLT gene. Thus, this study provides the first evidence for recurrent chromosomal translocations in PCNSLs. While they share similarities with extracerebral DLBCL with respect to the presence of IGH translocations, they appear to differ in the usage of translocation partner genes, which remain to be identified.

Adult↗
PubMedDate not supplied

Interphase cytogenetics of hematological neoplasms under the perspective of the novel WHO classification.

The novel WHO classification of tumors of hematopoietic and lymphoid tissues highlights the importance of genetic aberrations for the proper diagnosis of these malignancies. Among those techniques allowing detection of chromosomal changes, we have shown repeatedly that interphase fluorescence in situ hybridization (FISH) is currently the most robust and reliable technique for the diagnosis of lymphoma-associated translocations. Interphase FISH assays for the detection of the most frequent chromosomal alterations in myeloid and lymphoid disorders have become commercially available during the recent past. The sensitivity of some of these assays reaches levels below 1% providing valuable tools not only for diagnosis but also for follow-up and detection of minimal residual disease. Improvements of interphase FISH include the development of multicolor interphase FISH assays to detect several of the diagnostic changes in a single cell and of simultaneous fluorescence immunophenotyping (FICTION technique) to correlate phenotypic and genotypic cell features.

Hematologic Neoplasms↗