Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A patient with myelodysplastic syndrome (MDS) and a 47,XY,+21 karyotype at diagnosis, was documented to have a clonal chromosome 21 rearrangement, i(21q), four months before transformation to acute biphenotypic leukemia. For 4 months after transformation, isochromosome 21 persisted while the patient was receiving treatment with zidovudine. Vitamin D3 was added to zidovudine for an additional month, during which time the trisomy 21 clone reappeared as the predominant cell population. The unique aspects of this patient are the atypical evolution of chromosome 21, the transformation to biphenotypic leukemia, and the occurrence of i(21q) associated with biphenotypic leukemia evolving from an MDS.
 ...
PMID:Chromosome 21 rearrangement in acute biphenotypic leukemia. 136 Aug 69

Trisomy 21 as an acquired clonal chromosome change has been described in 642 of the 10,625 human neoplasms with chromosome aberrations known from the cytogenetic literature. A total of 590 of the 642 cases (92%) are hematologic disorders and malignant lymphomas. The incidence of trisomy 21 is similar (4.1%-6.7%) in acute myeloid leukemia (AML), chronic myeloid leukemia, myeloproliferative disorders, myelodysplastic syndromes, chronic lymphoproliferative disorders, and malignant lymphomas; it is substantially higher (14.8%) in acute lymphocytic leukemia (ALL). In most cases, the extra chromosome 21 is present together with other numerical and/or structural changes. Acquired trisomy 21 is the only karyotypic abnormality in only 0.4%. Trisomy 21 has never been reported as the sole anomaly in a solid tumor. The cytogenetic literature contains information on 62 patients with constitutional trisomy 21 and a malignant disorder in which the tumor cells have been analyzed by banding techniques. Thirty-four of the 62 patients had AML, 16 had ALL, and 2 had acute undifferentiated leukemia. The 52 leukemic Down syndrome (DS) cases account for 1.4% of the total acute leukemias, an overrepresentation that parallels the generally increased risk of leukemia development in DS. Sixty-three percent of the ALL patients and 79% of those with AML had additional changes superimposed on constitutional trisomy 21. These included several of the characteristic primary leukemia-associated aberrations: 5q-, 7q-, +8, and t(8;21) in AML, and t(1;19), t(4;11), 6q-, and 14q + in ALL. Thus, it seems that the pattern of acquired karyotypic changes is similar in patients with DS and in individuals with a normal constitutional karyotype.
 ...
PMID:Trisomy 21 in neoplastic cells. 214 59

Three cases of t(11;21)(q24;q11.2) myelodysplastic syndromes (MDS) showed karyotypic evolution resulting in the presence of two der(11)t(11;21) without normal chromosome 11 and with partial trisomy 21q. In one of these, we performed further molecular cytogenetic investigations which showed 1) that this rearrangement led to changes in the dosage and location of both c-ets 1 and c-ets 2 protooncogenes; and 2) that the presence of two 11q + chromosomes did not result from a nondisjunction, but that a second chromosome rearrangement had occurred. The final genetic imbalance resulting from this cytogenetic change involves at least hemizygosity for some sequences on the long arm of chromosome 11, including c-ets 1, plus trisomy for the most part of the long arm of chromosome 21, including c-ets 2.
 ...
PMID:Molecular cytogenetic analysis discloses complex genetic imbalance in a t(11;21) myelodysplastic syndrome. 218 96

Cytogenetic studies of 91 consecutive patients with therapy-related myelodysplasia or overt acute nonlymphocytic leukemia disclosed characteristic defects of chromosome 7 in 48 cases and of chromosome 5 in 21 cases. The chromosome 5 abnormalities were consistently present in all abnormal mitoses at the time of diagnosis, as were the chromosome 7 abnormalities in 45 of the 48 patients. Various abnormalities, primarily of the short arm of chromosome 17, were observed in 13 cases, abnormalities of the long arm of chromosome 21 were observed in 12 cases, and rearrangements of 11q23 were seen in nine cases. Thirteen patients presented a normal karyotype. Previous therapy with alkylating agents, the presence of an initial myelodysplastic phase, and abnormalities of chromosome 7 or 5 were interdependent. Patients with 11q23 rearrangement typically developed overt leukemia of FAB types M4 or M5a without myelodysplasia and with a short latent period. Evaluated by Cox regression analysis, complete remission of the primary malignancy and a malignant lymphoma as primary tumor were the two most important and independent prognostic factors indicating a longer survival (P = .008). In addition, the platelet count at diagnosis was a significant prognostic factor (P = .01). For the subgroup of 62 patients with myelodysplasia, the number of chromosome aberrations, the percentage of blasts in the bone marrow, and the hemoglobin level were other significant and independent prognostic factors (P = .05, .05, and .004, respectively). The most important predictive factor for a favorable response to intensive antileukemic chemotherapy in overt leukemia was the absence of a preceding myelodysplastic phase (P = .0014).
 ...
PMID:Chromosome aberrations and prognostic factors in therapy-related myelodysplasia and acute nonlymphocytic leukemia. 240 Aug 4

Twenty-four patients with Down syndrome and leukemia were studied. A strong male predominance (79%) was found. Age ranged between 18 months and 15 years (mean: 5 6/12); 54% of the patients were less than 4 years of age at the time of diagnosis. A preleukemic phase was noted in 6/24 patients. This phase, characterized essentially by thrombocytopenia, lasted from 2-8 months. Patients with preleukemia had unusual blast cell morphology and involvement of more than one cell line (dyserythropoiesis, hypolobulated megakaryocytes) and were probably M7 leukemias. All patients demonstrated severe methotrexate toxicity at standard methotrexate doses. Toxicity, manifesting as mouth ulcerations and bone marrow depression was seen regardless of the route of administration (oral, intrathecal or intravenous). A 30%-50% reduction of the standard dose was tolerated. Methotrexate absorption and clearance were studied in two patients and were found to be normal. We postulate that the observed toxicity of methotrexate may be due to a gene dosage effect for enzymes known to be on chromosome 21 and intervening in purine metabolism. Increased purine synthesis implies greater tetrahydrofolic acid demands and therefore greater sensitivity to an antifolate agent.
 ...
PMID:Down syndrome and leukemia: unusual clinical aspects and unexpected methotrexate sensitivity. 295 83

Development of myelodysplasia (MDS) with subsequent progression to acute myeloid leukemia (AML) is an example of the multistep process of malignant transformation in which each step often relates to genetic abnormalities that can be directly seen as chromosomal aberrations. Therapy-related MDS and AML (t-MDS and t-AML) may serve as an ideal model for a study of the genetic evolution of MDS and AML because chromosomal abnormalities are observed in most cases and because the disease is often diagnosed early due to a close patient follow-up. The cytogenetic characteristics at diagnosis were studied in 137 consecutive cases of t-MDS and t-AML, including 22 new cases, and correlated with the clinical characteristics and the course of the disease. Balanced translocations to chromosome bands 11q23 and 21q22 represent primary steps in pathways leading directly to overt t-AML. Specific chromosomal deletions or losses, on the other hand, represent primary or secondary events in alternative pathways leading to t-MDS with potential for subsequent transformation to overt t-AML. Loss of a whole chromosome 7 (-7) or deletion of its long arm (7q-) and deletion of the long arm of a chromosome 5 (5q-) were the most frequent primary abnormalities significantly related to t-MDS. Loss of a whole chromosome 5 (-5) was also a primary event, but surprisingly, was observed equally in t-MDS and in t-AML. Deletion of chromosome 13, including bands q13q14, was another less common primary aberration of t-MDS. Except for -7 and del(13q), these primary aberrations were most often observed together with secondary abnormalities. These included balanced aberrations involving band 3q26 and various deletions of chromosome 3, a gain of a whole chromosome 8, deletions of the short arm or loss of chromosomes 12 and 17, loss of a whole chromosome 18, and deletions of the short arm of chromosome 21. Deletions or loss or chromosomes 5 and 7 were significantly associated with previous therapy with alkylating agents (P = .002), and balanced translocations to chromosome bands 3q26, 11q23, and 21q22 were significantly associated with previous therapy with drugs targeting DNA-topoisomerase II (P < .00005). Other characteristic aberrations were not related to any specific type of therapy. The molecular changes believed to contribute to the development of t-MDS and t-AML have been identified for many of these chromosomal abnormalities.
 ...
PMID:Different genetic pathways in leukemogenesis for patients presenting with therapy-related myelodysplasia and therapy-related acute myeloid leukemia. 757 62

A nonrandom translocation between chromosomes 3 and 21, t(3;21)(q26.2;q22) has been detected in patients with a myelodysplastic syndrome or acute myeloid leukemia after treatment (t-MDS/t-AML) for a primary malignant disease and in chronic myelogenous leukemia in blast crisis (CML-BC). In these patients, the breakpoint on chromosome 21 is at band 21q22. This band is also involved in the t(8;21)(q22;q22) detected in 40% of the patients with acute myeloid leukemia subtype M2 (AML-M2) de novo who have an abnormal karyotype. In the t(8;21), the AML1 gene is the site of the breakpoint on chromosome 21. The AML1 gene is transcribed from telomere to centromere, and in the t(8;21) the 5' part of AML1 is fused to the ETO gene on chromosome 8 to produce the chimeric AML1/ETO on the der(8) chromosome. We found that AML1 is also rearranged in two t-AML patients and in one CML-BC patient with the t(3;21), but the breakpoints are approximately 40 to 60 kb downstream to those of AML-M2 patients. This region contains at least one additional exon of AML1, as determined by using an AML1 cDNA as a probe in Southern blot analysis. The t(3;21) breakpoints for the remaining patients could not be determined because, by fluorescence in situ hybridization analysis, the breaks are outside of the region covered by the available probes.
 ...
PMID:Involvement of the AML1 gene in the t(3;21) in therapy-related leukemia and in chronic myeloid leukemia in blast crisis. 849 Jan 81

A t(16;21) (q24;122) translocation was detected by fluorescence in situ hybridization in a patient with acute myeloblastic leukemia previously treated for malignant lymphoma. While the breakpoint on chromosome 21 was within the AML1 gene as determined by FISH, the gene partner on chromosome 16 could not be identified. Band 16q24 appears to be rearranged in several types of myeloid proliferation and a review of the literature shows that these rearrangements most often occur in secondary leukemia and myelodysplastic syndrome or are part of complex chromosomal rearrangements.
 ...
PMID:Secondary acute myeloblastic leukemia with t(16;21) (q24;q22). involving the AML1 gene. 893

16;21 translocation is a recurrent primary abnormality in acute myeloid leukemia (AML). The genes involved in this translocation are ERG on chromosome 21 and TLS/FUS on chromosome 16. The rearrangement of the two chromosomes forms the TLS/FUS-ERG fusion gene and produces a consistent chimeric transcript on the der (21) chromosome. In this study, we analyzed the clinical characteristics of 19 patients with t(16;21)-AML, including 2 patients who evolved from myelodysplastic syndrome, and detected the chimeric transcripts of the TLS/FUS-ERG fusion gene in the patients during various clinical stages by the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. We found that the patients with t(16;21) are characterized by a relatively younger age (median age, 22 years old), involvement of various subtypes of French-American-British classification and a poor prognosis: 18 of the 19 patients died of the disease (median survival was 16 months). Four types of TLS/FUS-ERG chimeric transcripts including a novel type were noted in the RT-PCR analysis. The novel transcript contained an additional 138 nucleotides consisting of TLS/FUS exon 8 and ERG exons 7 and 8 and had an in-frame fusion. These chimeric transcripts were consistently detectable in the samples obtained not only at diagnosis and relapse but also in short and long complete remission, suggesting that t(16;21)-AML is resistant to conventional chemotherapy. Thus, we recommend that t(16;21) should be monitored by RT-PCR even in clinical remission and the patients should be treated by other more powerful modality like stem-cell transplantation in the first remission.
 ...
PMID:Consistent detection of TLS/FUS-ERG chimeric transcripts in acute myeloid leukemia with t(16;21)(p11;q22) and identification of a novel transcript. 924 52

Down syndrome is caused by triplicate material of chromosome 21. The syndrome has a variable physical expression, but congenital cardiac defects, transient myelodysplasia of the newborn and duodenal atresia are highly specific for this chromosomal disorder. Routine health maintenance is important because infants and children with Down syndrome are more likely to have otitis media, thyroid disease, congenital cataracts, leukemoid reactions, dental problems and feeding difficulties. Since infants with this syndrome are prone to respiratory infections, immunization recommendations should be followed closely. Motor, language, social and adaptive skills should be assessed at each office visit. The psychosocial aspects of care should be discussed with the parents of an infant with Down syndrome. If necessary, the parents should be referred to family support and specialty resources. Institutionalization of infants with Down syndrome is now unlikely. With newer surgical techniques, early therapy to minimize developmental delay and proper health supervision, the functional prognosis for infants with Down syndrome is considerably improved.
 ...
PMID:Primary care of infants and young children with Down syndrome. 993 Jan 30


1 2 3 4 Next >>