Monosomy X as a recurring sole cytogenetic abnormality associated with myelodysplastic diseases

The spectrum of sex differences in cancer

Sex differences in cellular and systems biology have been evolutionarily selected to optimize reproductive success in all species with little (sperm) and big (ova) gamete producers. They are evident from the time of fertilization and accrue throughout development through genetic, epigenetic, and circulating sex hormone-dependent mechanisms. Among other effects, they significantly impact on chromatin organization, metabolism, cell cycle regulation, immunity, longevity, and cancer risk and survival. Sex differences in cancer should be expected and accounted for in basic, translational, and clinical oncology research.

The Genomics of Myelodysplastic Syndromes: Origins of Disease Evolution, Biological Pathways, and Prognostic Implications

The molecular pathogenesis of myelodysplastic syndrome (MDS) is complex due to the high rate of genomic heterogeneity. Significant advances have been made in the last decade which elucidated the landscape of molecular alterations (cytogenetic abnormalities, gene mutations) in MDS. Seminal experimental studies have clarified the role of diverse gene mutations in the context of disease phenotypes, but the lack of faithful murine models and/or cell lines spontaneously carrying certain gene mutations have hampered the knowledge on how and why specific pathways are associated with MDS pathogenesis. Here, we summarize the genomics of MDS and provide an overview on the deregulation of pathways and the latest molecular targeted therapeutics.

Sex chromosome loss after allogeneic hematopoietic stem cell transplant in patients with hematologic neoplasms: a diagnostic dilemma for clinical cytogeneticists

BACKGROUND

Sex chromosome loss (SCL), including loss of an X chromosome (-X) in females and loss of the Y chromosome (-Y) in males, resulting in a karyotype of 45,X, rarely occurs in patients post an allogeneic hematopoietic stem cell transplant (alloHSCT). However, origin of this abnormal clone and its clinical significance remains unknown.

RESULTS

We present 12 cases with SCL who underwent alloHSCT; 9 patients (4 men and 5 women with a median age of 56 years) developed isolated SCL after alloHSCT (Group I), and 3 patients (all women with a median age of 58 years) had a SCL before undergoing alloHSCT after which SCL disappeared (Group II). The primary neoplasms included chronic lymphocytic leukemia (n = 5), acute myeloid leukemia (n = 5), chronic myelogenous leukemia with nodal marginal zone lymphoma (n = 1) and Hodgkin lymphoma (n = 1). According to the donor/recipient relationship, their alloHSCT can be divided into sex-matched, HLA-matched, unrelated donors (n = 2); sex-mismatched, HLA-matched, unrelated donors (n = 4); sex-mismatched, HLA-matched, related donors (2 HLA-identical and 2 HLA-haploidentical cases) and sex-matched, HLA-matched, related donors (2 HLA-haploidentical cases). In Group I, isolated SCL was first detected with a median interval of 3 months (range 1 to 42 months) after the alloHSCT. By the end of clinical follow-up in patients in Group I, 7 patients expired with a median overall survival of 45 months (range 3 to 108 months) after alloHSCT and 33 months (range 0 to 66 months) after SCL detection. In Group II, 1 patient expired with a survival time of 54 months after the alloHSCT. Detection of SCL after alloHSCT can be transient, intermittent or persistent.

CONCLUSIONS

Interpretation of SCL is challenging in the context of alloHSCT. Chimerism testing is useful in determining the origin of SCL. In the case of SCL with donor/recipient chimerism, deduction of the SCL origin by all means and use of "-?X" or "-?Y" in the ISCN nomenclature are recommended. Clinical follow-up with closely monitoring the SCL by both cytogenetic and molecular analyses is needed.

Rare cytogenetic abnormalities in myelodysplastic syndromes

The karyotype represents one of the main cornerstones for the International Prognostic Scoring System (IPSS) and the revised IPSS-R (IPSS-R) that are most widely used for prognostication in patients with myelodysplastic syndromes (MDS). The most frequent cytogenetic abnormalities in MDS, i.e. del(5q), -7/del(7q), +8, complex karyotypes, or -Y have been extensively explored for their prognostic impact. The IPSS-R also considers some less frequent abnormalities such as del(11q), isochromosome 17, +19, or 3q abnormalities. However, more than 600 different cytogenetic categories had been identified in a previous MDS study. This review aims to focus interest on selected rare cytogenetic abnormalities in patients with MDS. Examples are numerical gains of the chromosomes 11 (indicating rapid progression), of chromosome 14 or 14q (prognostically intermediate to favorable), -X (in females, with an intermediate prognosis), or numerical abnormalities of chromosome 21. Structural abnormalities are also considered, e.g. del(13q) that is associated with bone marrow failure syndromes and favorable response to immunosuppressive therapy. These and other rare cytogenetic abnormalities should be integrated into existing prognostication systems such as the IPSS-R. However, due to the very low number of cases, this is clearly dependent on international collaboration. Hopefully, this article will help to inaugurate this process.

Cytogenetic analysis of CpG-oligonucleotide DSP30 plus Interleukin-2-Stimulated canine B-Cell lymphoma cells reveals the loss of one X Chromosome as the sole abnormality

Human and canine lymphoid neoplasms are characterized by non-random cytogenetic abnormalities. However, due to the low mitotic activity of the B cells, cytogenetic analyses of B-cell lymphoid proliferations are difficult to perform. In the present study we stimulated canine B-cell lymphoma cells with the immunostimulatory CpG-oligonucleotide DSP30 in combination with interleukin-2 (IL-2) and obtained an adequate number of metaphases. Cytogenetic analyses revealed the loss of one X chromosome as the sole cytogenetic aberration. Chromosome analysis of the corresponding blood showed a normal female karyotype. Monosomy X as the sole clonal chromosomal abnormality is found in human hematopoietic malignancies as well, thus the dog may serve as a promising animal model.

Somatic chromosome abnormalities in the lungs of patients with pulmonary arterial hypertension

RATIONALE

Vascular remodeling in pulmonary arterial hypertension (PAH) involves proliferation and migration of endothelial and smooth muscle cells, leading to obliterative vascular lesions. Previous studies have indicated that the endothelial cell proliferation is quasineoplastic, with evidence of monoclonality and instability of short DNA microsatellite sequences.

OBJECTIVES

To assess whether there is larger-scale genomic instability.

METHODS

We performed genome-wide microarray copy number analysis on pulmonary artery endothelial cells and smooth muscle cells isolated from the lungs of patients with PAH.

MEASUREMENTS AND MAIN RESULTS

Mosaic chromosomal abnormalities were detected in PAEC cultures from five of nine PAH lungs but not in normal (n = 8) or disease control subjects (n = 5). Fluorescent in situ hybridization analysis confirmed the presence of these abnormalities in vivo in two of three cases. One patient harbored a germline mutation of BMPR2, the primary genetic cause of PAH, and somatic loss of chromosome-13, which constitutes a second hit in the same pathway by deleting Smad-8. In two female subjects with mosaic loss of the X chromosome, methylation analysis showed that the active X was deleted. One subject also showed completely skewed X-inactivation in the nondeleted cells, suggesting the pulmonary artery endothelial cell population was clonal before the acquisition of the chromosome abnormality.

CONCLUSIONS

Our data indicate a high frequency of genetically abnormal subclones within PAH lung vessels and provide the first definitive evidence of a second genetic hit in a patient with a germline BMPR2 mutation. We propose that these chromosome abnormalities may confer a growth advantage and thus contribute to the progression of PAH.

Leukemias associated with Turner syndrome: Report of three cases and review of the literature

Cases of leukemia associated with Turner syndrome (TS) are rare. Here we report three TS patients with leukemia including one case of T-large granular lymphocyte leukemia (T-LGL), one rare case of coexistence of chronic lymphocytic leukemia (CLL) and idiopathic myelofibrosis (IMF) and one case of a patient with AML-M2 who received autologous stem cell transplantation (SCT). T-LGL and coexistence of CLL and IMF associated with TS are reported for the first time while the last case represents the first report of SCT in a leukemia patient with TS. Our cases and the limited data of previously reported leukemia patients with TS suggest that TS is not associated with a specific type of leukemia and that presentation, clinical course and response to treatment are similar to that of the non-TS leukemia patients. However, these patients may have a higher risk of liver complications. Interestingly, in the mosaic TS patients, the abnormal clones were restricted to the monosomic 45,X cells, indicating that the leukemic clones possibly originate from the monosomic cell line. Even in cases with no additional chromosome abnormalities, the ratio of X/XX cells in bone marrow cells was significantly increased compared to that in constitutional karyotype, indicating that monosomic cells possibly provide a survival advantage for leukemia cells or that reduced programmed cell death may be responsible for the expansion of the monosomic cells.

Acquired biclonal chromosome X aberrations without autosomal chromosomal anomalies in acute myeloid leukemia

Acquired clonal chromosome X aberrations, whether numerical or structural, as the sole chromosomal anomaly in acute myeloid leukemia (AML) are very uncommon. The scarcity of nonconstitutional chromosome X aberrations detected in AML has prevented any meaningful evaluation of their prognostic significance. In this report, we describe the case of a patient with AML who had the unusual acquired karyotype of 45,X/-X,46,X,i(X)(q10) on presentation and 45,X,-X,add(19)(p13.3) on relapse. We also briefly review the literature on acquired numerical and structural chromosome X aberrations as the sole chromosomal anomaly in AML. This case adds to the sparse body of literature regarding chromosome X aberrations in AML. More case reports are needed to further elucidate the importance of such aberrations.

[Incidence and types of constitutional chromosomal abnormalities in patients with hematologic malignancies.]

BACKGROUND

It is important to distinguish between the constitutional and acquired chromosomal abnormality in bone marrow of the patients with the hematologic malignancies, since the constitutional chromosomal abnormality will be continuously observed, even though in remission status of the disease. In this study, we investigated the incidence and types of constitutional chromosomal abnormalities in patients with the hematologic malignancies.

METHODS

This study included 396 patients with benign hematologic disorders and 634 with hematologic malignancies. The cytogenetic analysis of bone marrow aspirates were performed by direct or/and short term culture (24-48 hours). The constitutional chromosomal abnormality was confirmed by phytohemagglutinin-stimulated 72 hour culture with peripheral blood lymphocytes.

RESULTS

The incidence of constitutional chromosomal abnormalities was 2.8% in patients with benign hematologic disorders and 2.4% in patients with hematologic malignancies. Among the patients with constitutional chromosomal abnormalities and hematologic malignancies, 12 were males and 3 females. Eleven patients had an age greater than 20 years. One patient had trisomy 21, 1 reciprocal translocation, 1 robertsonian translocation, 3 sex chromosome aneuploidy and 9 inv(9). Two patients showed both constitutional and acquired chromosomal abnormalities on the same chromosome. The constitutional chromosomal abnormality was continuously observed in remission status of hematologic malignancies.

CONCLUSIONS

The incidence of the constitutional chromosomal abnormalities was low in patients with hematologic malignancies, but the chromosome study with peripheral blood or skin fibroblasts may be necessary for determining accurate cytogenetic response during follow up.

Constitutional chromosome aberrations as pathogenetic events in hematologic malignancies

A predisposition to tumor development is associated with some constitutional chromosomal abnormalities. Investigations of families with an apparent hereditary cancer and constitutional chromosome rearrangements have led to the molecular identification of tumor suppressor genes. Under the somatic mutation theory for the development of cancer, two mutational events are required. The first step may be a constitutional event and the second an acquired genetic mutation. Cytogenetic studies were performed on 5633 bone marrow specimens from patients with hematologic malignancies from a single institution. Fifty cases of constitutional chromosome aberrations were detected. Data collected from the literature and from our series are reviewed and compared with the incidence of specific constitutional chromosome aberrations in the newborn population. Possible mechanisms that may predispose individuals with constitutional chromosome aberrations to the development of a hematologic malignancy are reviewed.

[Biologic and clinical relevance of cytogenetic analysis in primary myelodysplastic syndromes]

Cytogenetic abnormalities in myelodysplastic syndromes (MDS) are complex and heterogeneous. The most frequent rearrangements (gains or losses of genetic material) vary from patient to patient, and within the same patient. The prognostic value of these rearrangements has been extensively studied. They allowed the definition of a risk based classification system for MDS (the International Scoring System for evaluating Prognosis, IPSS), proven to be a highly useful method for evaluating prognosis in MDS patients. Despite recent progress in mapping and definition of minimally deleted chromosomal regions, the primary critical genetic events remain to be determined. The recurrent cytogenetic abnormalities associated with MDS are likely to be secondary events contributing to but not initiating the neoplastic phenotype of the disease.

Monosomy X as the sole cytogenetic abnormality in acute lymphoblastic leukemia: a report of two new patients

Monosomy X as the sole acquired cytogenetic abnormality is usually found in myeloid hematological malignancies, especially those with myelodysplastic features. Only three cases of acute lymphoblastic leukemia (ALL) with this abnormality have been previously reported. We add two cases to this series and comment on the likelihood of a tumor suppressor gene being located on the X chromosome.

Molecular features of primary MDS with cytogenetic changes

Cytogenetic changes in primary myelodysplastic syndromes (MDS) have been extremely useful to identify clonality and to define specific clinico-pathological entities. More recently, with the development of DNA technology, a bulk of new information has been added to classical cytogenetics. Genes corresponding to chromosomal breakpoints implicated in reciprocal translocations have been cloned. Search for the minimal lost region has been the aim of the so-called deletion mapping approach to pick up the hypothetical suppressor gene(s) critical for typical deletions of MDS. Correlation has been found between gene mutations, deletions, expression, and clinical-hematological or cytogenetic features of MDS. Integration of fluorescence in situ hybridization at DNA level and of immunophenotyping at cellular level is an elegant tool to investigate clonal affiliation in MDS with distinct genetic changes.