Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Noonan syndrome (NS) is a multiple malformation syndrome where confirmation of diagnosis is difficult in the newborn. We report a case of a dysmorphic neonate who presented with bilateral chylous effusions and juvenile myelomonocytic leukemia where NS was confirmed by the presence of PTPN11 mutation. Juvenile myelomonocytic leukemia in NS is uncommon. The leukemia is usually self-limiting but lethal cases have been reported. Decisions regarding need for the treatment are unclear and further understanding of the genotype-phenotype relationships in PTPN11 mutations may help direct this.
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PMID:Respiratory failure, juvenile myelomonocytic leukemia, and neonatal Noonan syndrome. 1741 70

A 13-month-old female underwent unrelated cord blood transplantation (CBT) for juvenile myelomonocytic leukemia (JMML). In spite of progression of the disease after a conditioning regimen with high-dose chemotherapy, a complete remission was induced in concordance with development of acute GVHD after reduction of the immunosupressant. She has been in complete remission for 1 year after transplantation. This case illustrates that CBT can provide a potent graft versus leukemia (GVL) effect against JMML.
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PMID:Graft versus leukemia effect against juvenile myelomonocytic leukemia after unrelated cord blood transplantation. 1743 89

The number of new anti-cancer drugs emerging for clinical trials in humans far exceeds the availability of pediatric acute leukemia patients to be entered into clinical trials. Therefore, preclinical testing of new agents for the treatment of childhood acute leukemia is essential to ensure that the most promising drugs are prioritized to enter clinical trials. Historically, the murine system has been central to modeling human leukemia in vivo. A greater knowledge of the molecular lesions underlying particular subtypes of leukemia has led to the generation of genetically engineered murine models, generally involving the knockin or knockout of certain genes and fusion genes at their normal genetic locus. However, the most predominant in vivo models for preclinical drug testing have been human leukemia xenografts. Successful engraftment of all subtypes of acute lymphoblastic leukemia, most subtypes of acute myeloid leukemia as well as juvenile myelomonocytic leukemia, chronic myeloid leukemia and chronic lymphocytic leukemia have been described in various immune-deficient murine hosts. Preclinical testing of novel therapeutics in vivo will likely identify the most promising new agents to enter clinical trials, and will allow their future use to be optimized in combination with other novel and conventional chemotherapeutics.
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PMID:In vivo models of childhood leukemia for preclinical drug testing. 1758 33

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder caused by mutations in the NF1 gene. Patients with NF1 have a higher risk to develop juvenile myelomonocytic leukemia (JMML) with a possible progression toward acute myeloid leukemia (AML). In an oligo array comparative genomic hybridization-based screening of 103 patients with pediatric T-cell acute lymphoblastic leukemia (T-ALL) and 71 patients with MLL-rearranged AML, a recurrent cryptic deletion, del(17)(q11.2), was identified in 3 patients with T-ALL and 2 patients with MLL-rearranged AML. This deletion has previously been described as a microdeletion of the NF1 region in patients with NF1. However, our patients lacked clinical NF1 symptoms. Mutation analysis in 4 of these del(17)(q11.2)-positive patients revealed that mutations in the remaining NF1 allele were present in 3 patients, confirming its role as a tumor-suppressor gene in cancer. In addition, NF1 inactivation was confirmed at the RNA expression level in 3 patients tested. Since the NF1 protein is a negative regulator of the RAS pathway (RAS-GTPase activating protein), homozygous NF1 inactivation represent a novel type I mutation in pediatric MLL-rearranged AML and T-ALL with a predicted frequency that is less than 10%. NF1 inactivation may provide an additional proliferative signal toward the development of leukemia.
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PMID:Leukemia-associated NF1 inactivation in patients with pediatric T-ALL and AML lacking evidence for neurofibromatosis. 1817 6

Noonan syndrome (NS) patients are at increased risk for developing juvenile myelomonocytic leukemia (JMML), an aggressive clonal disorder of aberrant cell proliferation. Many NS patients exhibit spontaneously remitting monocytosis and transient myeloproliferation. The distinction between bone marrow hyperproliferation due to germline mutation and leukemia resulting from clonal transformation can be difficult in NS patients. The GM-CSF hypersensitivity assay, diagnostic of sporadic JMML, can be positive in NS patients at baseline. In this report, we demonstrate the utility of determining the clonal status of the monocyte population by the HUMARA assay in distinguishing JMML and benign myeloproliferation in female NS patients.
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PMID:Use of human androgen receptor gene analysis to aid the diagnosis of JMML in female noonan syndrome patients. 1845 68

The 2001 World Health Organization (WHO)-sponsored classification of hematopoietic tumors has, for the first time, clearly defined a group of rare myeloid neoplasms termed myelodysplastic/myeloproliferative diseases (MDS/MPDs). This group includes three main entities, chronic myelomonocytic leukemia, atypical chronic myeloid leukemia and juvenile myelomonocytic leukemia, and also several less well defined, 'unclassifiable' disorders with MDS/MPN-like features. In the upcoming fourth edition of the WHO fascicle, due out later this year, the term 'MPD' is replaced by 'myeloproliferative neoplasm (MPN)'. Accordingly, the term MDS/MPD is being replaced by 'MDS/MPN' that will be used in this review. Although much progress has been made in understanding the molecular pathogenesis of myeloid neoplasms, most of the diseases included in the group of MDS/MPN still remain 'clinicopathologically assigned'. In other words, they can only be accurately categorized by a careful multiparametric approach that is based on the integration of bone marrow and peripheral blood morphology with other laboratory and clinical findings. The current 'spotlight' review provides practical guidelines, which should allow for a reproducible classification of these uncommon neoplasms when encountered in clinical practice.
Leukemia 2008 Jul
PMID:The myelodysplastic/myeloproliferative neoplasms: myeloproliferative diseases with dysplastic features. 1848 Aug 33

In 1982, chronic myelomonocytic leukemia (CMML) was first classified in the category of myelodysplastic syndromes (MDSs), but it always seemed somewhat out of place compared with the rest of the MDS categories. In the 1990s, many argued that there were two different forms of CMML, a proliferative type and a myelodysplastic type. Then in 2001 the World Health Organization created a new category called the mixed myelodysplastic/myeloproliferative diseases, under which CMML was included. Although we still do not understand much about CMML pathogenesis nor do we have specific therapies for this disease, at least now most agree that it is in an appropriate category such that other areas of investigation can now proceed. On the other hand, we now understand a great deal of the pathogenesis underlying the disease now called juvenile myelomonocytic leukemia (JMML). JMML also fits in the new category of mixed myelodysplastic/myeloproliferative diseases. JMML is an excellent model malignancy for investigating and understanding dysregulated and aberrant signal transduction in the Ras pathway. It has also served as a teaching tool for exploring inherited predispositions to cancer.
Leukemia 2008 Jul
PMID:Juvenile myelomonocytic leukemia and chronic myelomonocytic leukemia. 1854 91

Juvenile xanthogranuloma is a benign, self-healing disorder with characteristic lesions mainly involving the skin. Although most patients with juvenile xanthogranuloma have only cutaneous symptoms, recent articles have documented extracutaneous manifestations: systemic involvement of many organs has been reported and there is a known association between juvenile xanthogranuloma and childhood leukemia, most commonly juvenile chronic myelogenous leukemia. This case provides further corroboration, that in rare instances, juvenile xanthogranuloma may be associated with hematologic malignancies.
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PMID:Eruptive juvenile xanthogranuloma associated with relapsing acute lymphoblastic leukemia. 1878

Germline mutations in PTPN11 gene cause Noonan syndrome and the clinically similar LEOPARD syndrome (LS). LS is a rare congenital developmental disorder characterized by multiple lentigines, cardiac abnormalities, facial dysmorphism, retardation of growth, and deafness. Mutations in exons 7 and 12 of the PTPN11 gene can be identified in nearly 90% of patients with LS. PTPN11 gene encodes for an ubiquitously expressed protein tyrosine phosphatase SHP-2 involved in a variety of intracellular signaling processes in development and hematopoiesis. Somatic PTPN11 mutations contribute to leukemogenesis in children with hematologic malignancies including juvenile myelomonocytic leukemia, acute lymphoblastic leukemia, acute myeloid leukemia, and myelodysplasia. Two cases of leukemia (acute myeloid leukemia) have been reported in children with LS. The authors describe for the first time a girl with genetically confirmed LEOPARD syndrome presenting with common acute lymphoblastic leukemia.
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PMID:Common acute lymphoblastic leukemia in a girl with genetically confirmed LEOPARD syndrome. 1879 37

NF1 inactivation occurs in specific human cancers, including juvenile myelomonocytic leukemia, an aggressive myeloproliferative disorder of childhood. However, evidence suggests that Nf1 loss alone does not cause leukemia. We therefore hypothesized that inactivation of the Nf1 tumor suppressor gene requires cooperating mutations to cause acute leukemia. To search for candidate genes that cooperate with Nf1 deficiency in leukemogenesis, we performed a forward genetic screen using retroviral insertion mutagenesis in Nf1 mutant mice. We identified 43 common proviral insertion sites that contain candidate genes involved in leukemogenesis. One of these genes, Bcl11a, confers a growth advantage in cultured Nf1 mutant hematopoietic cells and causes early onset of leukemia of either myeloid or lymphoid lineage in mice when expressed in Nf1-deficient bone marrow. Bcl11a-expressing cells display compromised p21(Cip1) induction, suggesting that Bcl11a's oncogenic effects are mediated, in part, through suppression of p21(Cip1). Importantly, Bcl11a is expressed in human chronic myelomonocytic leukemia and juvenile myelomonocytic leukemia samples. A subset of AML patients, who had poor outcomes, of 16 clusters, displayed high levels of BCL11A in leukemic cells. These findings suggest that deregulated Bcl11a cooperates with Nf1 in leukemogenesis, and a therapeutic strategy targeting the BCL11A pathway may prove beneficial in the treatment of leukemia.
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PMID:A retroviral mutagenesis screen reveals strong cooperation between Bcl11a overexpression and loss of the Nf1 tumor suppressor gene. 1894 76


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