Regions of homozygosity confer a worse prognostic impact in myelodysplastic syndrome with normal karyotype

Half of the myelodysplastic syndromes (MDS) have normal karyotype by conventional banding analysis. The percentage of true normal karyotype cases can be reduced by 20-30% with the complementary application of genomic microarrays. We here present a multicenter collaborative study of 163 MDS cases with a normal karyotype (≥10 metaphases) at diagnosis. All cases were analyzed with the ThermoFisher® microarray (either SNP 6.0 or CytoScan HD) for the identification of both copy number alteration(CNA) and regions of homozygosity (ROH). Our series supports that 25 Mb cut-off as having the most prognostic impact, even after adjustment by IPSS-R. This study highlights the importance of microarrays in MDS patients, to detect CNAs and especially to detect acquired ROH which has demonstrated a high prognostic impact.

Cytogenetic peripheral blood monitoring in azacitidine treated patients with high-risk MDS/sAML: A monocentric real-world experience

In this single center retrospective analysis 76 patients with high-risk (HR) myelodysplastic syndrome (MDS) treated with azacitidine (AZA) were reviewed for response, especially cytogenetic response (cyR) using repeated chromosome banding analyses (CBA) of bone marrow (bm) metaphases and frequent sequential Fluorescence-in-situ Hybridization (FISH) analyses of immunomagnetically enriched CD34 + circulating peripheral blood cells (CD34 +pb-FISH). In total, 526 CD34 +pb-FISH analyses and 236 CBA were examined. Median observation time was 8.45 months, median number of AZA cycles applied was 8, median overall survival (OS) was 14.9 months, 42.1 % of patients responded to therapy according to IWG criteria: 5 complete response (CR), 0 partial response (PR), 12 bmCR, 15 stable disease with hematologic improvement (HI). HI was reached in 36.8 % of patients, 31.5 % became transfusion-independent. By CBA or CD34 +pb-FISH 20.4 % and 31.6 % of patients showed cyR, respectively. HI rate was significantly higher in cytogenetic responders than in non-responders, but there was no impact on OS or leukemia-free-survival. Cytogenetic responders showed significantly better OS than non-responders. Patients with ≥ 6 AZA cycles had significantly better OS than patients with < 6 cycles applied. Karyotype evolution (KE) as a manifestation of cytogenetic progression was diagnosed in 29.5 % and 17.1 % of patients by CBA and CD34 +pb-FISH, respectively. KE was associated with significantly poorer OS and leukemia-free-survival.

Impact of somatic mutations in myelodysplastic patients with isolated partial or total loss of chromosome 7

Monosomy 7 [-7] and/or partial loss of chromosome 7 [del(7q)] are associated with poor and intermediate prognosis, respectively, in myelodysplastic syndromes (MDS), but somatic mutations may also play a key complementary role. We analyzed the impact on the outcomes of deep targeted mutational screening in 280 MDS patients with -7/del(7q) as isolated cytogenetic abnormality (86 with del(7q) and 194 with -7). Patients with del(7q) or -7 had similar demographic and disease-related characteristics. Somatic mutations were detected in 79% (93/117) of patients (82% in -7 and 73% in del(7q) group). Median number of mutations per patient was 2 (range 0-8). There was no difference in mutation frequency between the two groups. Patients harbouring ≥2 mutations had a worse outcome than patients with <2 or no mutations (leukaemic transformation at 24 months, 38% and 20%, respectively, p = 0.044). Untreated patients with del(7q) had better overall survival (OS) compared with -7 (median OS, 34 vs 17 months, p = 0.034). In multivariable analysis, blast count, TP53 mutations and number of mutations were independent predictors of OS, whereas the cytogenetic subgroups did not retain prognostic relevance. This study highlights the importance of mutational analysis in terms of prognosis in MDS patients with isolated -7 or del(7q).

Comprehensive analysis of isolated der(1;7)(q10;p10) in a large international homogenous cohort of patients with myelodysplastic syndromes

The karyotype is a strong independent prognostic factor in myelodysplastic syndromes (MDS). Since the implementation of the new comprehensive cytogenetic scoring system for MDS, chromosome 7 anomalies are no longer generally assigned to poor risk features but are thoroughly separated. However, der(1;7)(q10;p10), hereinafter der(1;7), is merged into the group labeled "any other single" and belongs to the intermediate risk group, just by definition due to lack of adequate clinical data. The aim of our international collaborative was to clarify the "real" prognostic impact of der(1;7) on a homogenous and well-documented data base. We performed detailed analysis of 63 MDS patients with isolated der(1;7) constituting the largest cohort hitherto reported. Furthermore, clinical data are compared with those of patients with isolated del(7q) and isolated monosomy 7. Median overall survival (OS) of patients with der(1;7) is 26 months (hazard ratio (HR) 0.91 for del(7q) vs der(1;7) and 2.53 for monosomy 7 vs der(1;7)). The der(1;7) is associated with profound thrombocytopenia most probably causing the reduced OS which is in striking contrast to the low risk for AML transformation (HR 3.89 for del(7q) vs der(1;7) and 5.88 for monosomy 7 vs der(1;7)). Molecular karyotyping indicates that der(1;7) is generated in a single step during mitosis and that a chromosomal imbalance rather than a single disrupted gene accounts for malignancy. Thus, the current cytogenetic scoring system assigning isolated der(1;7) to the intermediate risk group is now confirmed by a sufficient data set.

Detailed analysis of clonal evolution and cytogenetic evolution patterns in patients with myelodysplastic syndromes (MDS) and related myeloid disorders

Clonal cytogenetic evolution (CE) (i.e., acquisition of new chromosomal aberrations over time) is relevant for the progression of myelodysplastic syndromes (MDS). We performed detailed analysis of CE in 729 patients with MDS and related disorders. Patients with CE showed shorter survival (median OS 18.0 versus 53.9 months; P < 0.01), higher leukemic transformation rate (48.0% versus 21.4%; P < 0.01) and shorter intervals to leukemic transformation (P < 0.01). Two main CE patterns were detected: early versus late CE (median onset 5.3 versus 21.9 months; P < 0.01) with worse survival outcomes for early CE. In the case of CE, del (7q)/−7 (P = 0.020) and del (17p) (P = 0.002) were especially unfavorable. Extending the evolution patterns from Tricot et al. (1985) forming five subgroups, prognosis was best (median OS not reached) in patients with “transient clones/changing clone size”, whereas those with “CE at diagnosis” showed very poor outcomes (P < 0.01 for comparison of all). Detailed sequential cytogenetic analysis during follow-up improves prognostication in MDS patients and acknowledges the dynamic biology of the disease. Evidence, time-point, and patterns of cytogenetic clonal evolution should be included into future prognostic scoring systems for MDS.

Identification of a new gene regulatory circuit involving B cell receptor activated signaling using a combined analysis of experimental, clinical and global gene expression data

To discover new regulatory pathways in B lymphoma cells, we performed a combined analysis of experimental, clinical and global gene expression data. We identified a specific cluster of genes that was coherently expressed in primary lymphoma samples and suppressed by activation of the B cell receptor (BCR) through αIgM treatment of lymphoma cells in vitro. This gene cluster, which we called BCR.1, includes numerous cell cycle regulators. A reduced expression of BCR.1 genes after BCR activation was observed in different cell lines and also in CD10⁺ germinal center B cells. We found that BCR activation led to a delayed entry to and progression of mitosis and defects in metaphase. Cytogenetic changes were detected upon long-term αIgM treatment. Furthermore, an inverse correlation of BCR.1 genes with c-Myc co-regulated genes in distinct groups of lymphoma patients was observed. Finally, we showed that the BCR.1 index discriminates activated B cell-like and germinal centre B cell-like diffuse large B cell lymphoma supporting the functional relevance of this new regulatory circuit and the power of guided clustering for biomarker discovery.

Influence of total genomic alteration and chromosomal fragmentation on response to a combination of azacitidine and lenalidomide in a cohort of patients with very high risk MDS

We genetically analyzed a group of high risk MDS/AML patients treated by a combination of azacitidine and lenalidomide. In our cohort, the extent of genetic rearrangements was associated with outcome and response to treatment. The size of total genomic aberrations as defined by molecular karyotyping (SNP-array analysis) was a predictive marker for overall survival. TP53 mutations were associated with therapy refractoriness only if accompanied by heavily rearranged chromosomes. This study suggests a potential value of molecular karyotyping as a method to objectivate comprehensively the extent of genetic alterations in high risk patients with complex karyotypes, especially if the clinical value of the size of total genomic aberrations and the fragmentation status of single chromosomes could be evaluated in larger therapy trials.

Validation of cytogenetic risk groups according to International Prognostic Scoring Systems by peripheral blood CD34+FISH: results from a German diagnostic study in comparison with an international control group

International Prognostic Scoring Systems are used to determine the individual risk profile of myelodysplastic syndrome patients. For the assessment of International Prognostic Scoring Systems, an adequate chromosome banding analysis of the bone marrow is essential. Cytogenetic information is not available for a substantial number of patients (5%-20%) with dry marrow or an insufficient number of metaphase cells. For these patients, a valid risk classification is impossible. In the study presented here, the International Prognostic Scoring Systems were validated based on fluorescence in situ hybridization analyses using extended probe panels applied to cluster of differentiation 34 positive (CD34(+)) peripheral blood cells of 328 MDS patients of our prospective multicenter German diagnostic study and compared to chromosome banding results of 2902 previously published patients with myelodysplastic syndromes. For cytogenetic risk classification by fluorescence in situ hybridization analyses of CD34(+) peripheral blood cells, the groups differed significantly for overall and leukemia-free survival by uni- and multivariate analyses without discrepancies between treated and untreated patients. Including cytogenetic data of fluorescence in situ hybridization analyses of peripheral CD34(+) blood cells (instead of bone marrow banding analysis) into the complete International Prognostic Scoring System assessment, the prognostic risk groups separated significantly for overall and leukemia-free survival. Our data show that a reliable stratification to the risk groups of the International Prognostic Scoring Systems is possible from peripheral blood in patients with missing chromosome banding analysis by using a comprehensive probe panel (clinicaltrials.gov identifier:01355913).

Molecular cytogenetic monitoring from CD34+ peripheral blood cells in myelodysplastic syndromes: first results from a prospective multicenter German diagnostic study

The gold standard of cytogenetic analysis in myelodysplastic syndromes (MDS) is conventional chromosome banding (CCB) analysis of bone marrow (BM) metaphases. Most aberrations can also be detected by fluorescence-in situ-hybridization (FISH). For this prospective multicenter German diagnostic study (www.clinicaltrials.gov: #NCT01355913) 360 patients, as yet, were followed up to 3 years by sequential FISH analyses of immunomagnetically enriched CD34+ peripheral blood (PB) cells using comprehensive FISH probe panels, resulting in a total number of 19,516 FISH analyses. We demonstrate that CD34+ PB FISH correlates significantly with CCB analysis and represents a feasible method for a reliable non-invasive cytogenetic monitoring from PB.

INSL5-deficient mice display an alteration in glucose homeostasis and an impaired fertility

Insulin-like factor 5 (INSL5), a member of the insulin superfamily, is expressed in the colorectum and hypothalamus. To facilitate studies into the role of INSL5, we generated Insl5(-/-) mice by gene targeting. Insl5(-/-) mice were born in the expected Mendelian ratio, reached normal body weight, but displayed impaired male and female fertility that are due to marked reduction in sperm motility and irregular length of the estrous cycle. Furthermore, Insl5(-/-) mice showed impairment in glucose homeostasis with characteristic elevation of serum glucose levels at an advanced age. Glucose and insulin tolerance tests revealed that the increased blood glucose in Insl5(-/-) mice was due to glucose intolerance resulting from reduced insulin secretion. Morphometric and immunohistological analyses revealed that the Insl5(-/-) mice had markedly reduced average islets area and β-cell numbers. Furthermore, immunohistochemistry showed the expression of INSL5 in enteroendocrine cells in the colorectal epithelium and the presence of its putative receptor relaxin family peptide receptor 4 in pancreatic islet cells. These results suggest the potential role of INSL5 signaling in the regulation of insulin secretion and β-cell homeostasis.

FISH analysis of circulating CD34+ cells as a new tool for genetic monitoring in MDS: verification of the method and application to 27 MDS patients

In myelodysplastic syndromes (MDS) chromosomal anomalies can be identified in 50-80% of patients. They have a diagnostic and prognostic impact and are increasingly considered for therapeutic decisions. Cytomorphology and cytogenetic analyses of bone marrow (bm) cells define the goldstandard to diagnose MDS patients and to document treatment response. We present a novel method using peripheral blood (pb) for frequent cytogenetic monitoring: after immunomagnetic cell separation circulating CD34+ cells were analysed by fluorescence in situ hybridization (FISH). We compared FISH analyses of enriched and non-enriched pb and bm cells with conventional chromosome banding analyses of bm metaphases: analysing circulating CD34+ cells by FISH is a sensitive, reliable method to measure the abnormal cell clones in pb. This method is practicable, non-invasive, representative for the clonal situation in the bm, and has a predictive value. Its feasibility was proven in a cohort of 27 MDS patients.

Inactivation of insulin-like factor 6 disrupts the progression of spermatogenesis at late meiotic prophase

Insulin-like factor 6 (INSL6), a member of the insulin-like superfamily, is predominantly expressed in male germ cells. Expression of the Insl6 is first detected in mouse testis at postnatal d 15 when the first wave of spermatogenesis progresses to pachytene spermatocytes. To elucidate the role of INSL6 in germ cell development, we generated Insl6-deficient mice. The majority of the Insl6-deficient males on a hybrid genetic background exhibited impaired fertility, whereas females were fertile. The number of mature sperm and sperm motility were drastically reduced in the epididymis. The reduced sperm count could be due to apoptotic death of a significant number of developing germ cells. Analysis of germ cell development during the juvenile life showed an arrest of the first wave of spermatogenesis in late meiotic prophase. RNA analysis revealed a significant decrease in expression of late meiotic- and postmeiotic-specific marker genes, whereas expression of early meiotic-specific genes remains unaffected in the Insl6(-/-) testes. These results demonstrate that INSL6 is required for the progression of spermatogenesis.

Directed overexpression of insulin in Leydig cells causes a progressive loss of germ cells

The primary goal of this study was to determine the 5'region of the Insl3 gene that specifically targets the expression of human insulin to Leydig cells, and to explore whether the testicular proinsulin is efficiently processed to insulin that is able to rescue the diabetes in different mouse models of diabetes. We show here that the sequence between nucleotides -690 and +4 of mouse Insl3 promoter is sufficient to direct the Leydig cell-specific expression of the human insulin transgene (Insl3-hIns). We also found that the 3'untranslated region (3'UTR) of Insl3 was effective in enhancing transgene expression of the insulin in vivo. Expression analysis revealed that the temporal expression pattern of the hIns transgene in Leydig cells of transgenic testes is roughly the same as that of the endogenous Insl3. Despite the Leydig cells translate human proinsulin and secrete a significant level of free C-peptide into the serum, the Leydig cell-derived insulin is not able to overcome the diabetes in different mouse models of diabetes, suggesting a lack of glucose sensing mechanisms in the Leydig cells. A consequence of overexpression of the human proinsulin in Leydig cells was the decrease of fertility of transgenic males at older ages. Germ cells in transgenic males were able to initiate and complete spermatogenesis. However, there was a progressive and age-dependent degeneration of the germ cells that lead to male infertility with increasing age.

Prenatal diagnosis of Roberts syndrome and detection of an ESCO2 frameshift mutation in a Pakistani family

OBJECTIVES

We report two siblings with Roberts syndrome (RBS), and an attempt to delineate the underlying molecular mechanism leading to familial recurrence.

METHODS

Cytogenetic studies and direct sequencing of the ESCO2 gene were carried out in the second affected fetus and the parents. Fetal DNA was obtained from amniocytes after amniocentesis. Parental DNA was obtained from peripheral blood samples.

RESULTS

Cytogenetic analysis of amniocytes revealed a normal male karyotype in 20 analyzed metaphases and chromosomal aneuploidies in 10 metaphases. All metaphases displayed premature separation of centromeres and puffing of heterochromatic regions near the centromere. A homozygous mutation leading to a frameshift in ESCO2 was identified in the fetal DNA sample. Both parents are heterozygous carriers of the same mutation.

CONCLUSION

The present case demonstrates the prenatal diagnosis of RBS associated with a frameshift mutation in ESCO2.

Molecular cytogenetic analysis of a de novo balanced X;autosome translocation: Evidence for predominant inactivation of the derivative X chromosome in a girl with multiple malformations

We report on the characterization of a de novo, apparently balanced translocation t(X;15)(p11.3;q26) detected in a girl with multiple congenital malformations. Replication banding studies on Epstein-Barr virus transformed peripheral blood lymphocytes revealed non-random X chromosome inactivation with predominant inactivation of the derivative X chromosome. Using chromosomal fluorescence in situ hybridization (FISH), we located the breakpoints to a 30 kb region on the short arm of the X chromosome band p11.3 and to a 160 kb region defined by BAC RP11-89K11 on the long arm of chromosome 15. Our data suggest that the disruption/disturbance of plant homeo domain (PHD) zinc finger gene KIAA0215 or of another gene (RGN, RNU12, P17.3, or RBM10) in the breakpoint region on the X chromosome is not well tolerated and leads to the selection of cells with an active non-rearranged X chromosome.