Biomedical subjects
Publications and source records attributed to N Kardon.
Two cases of acute megakaryoblastic leukemia are reported. The diagnoses were confirmed by clinical, morphologic, and cytochemical analysis. Karyotypic analysis demonstrated monosomy 5 in both patients, providing further evidence that acute megakaryoblastic leukemia is a subset of the acute nonlymphocytic leukemias and may be etiologically related to the myelodysplastic syndromes.
Pseudomosaicism is of particular concern in prenatal diagnosis when it involves mosaicism for a cytogenetic abnormality associated with a clinical syndrome which is compatible with postnatal life, such as trisomies for chromosomes 13, 18, and 21. The lack of data regarding the outcome of pregnancies involving these specific kinds of pseudomosaicism makes genetic counselling difficult. Three cases of prenatal diagnosis of pseudomosaicism for trisomy 13, each of which had a normal outcome, will be presented (Tables 1 and 2). The three main areas for consideration are: (1) the genetic counselling issues, (2) the additional prenatal diagnostic options available to evaluate the status of the fetus in an attempt to identify some of the clinical features of trisomy 13, and (3) the outcome of the pregnancies.
Most individuals with cat eye syndrome (CES) have a supernumerary bisatellited chromosome which, on the basis of cytogenetic evidence, has been reported to originate from either chromosome 13 or 22. To resolve this question, a single-copy DNA probe, D22S9, was isolated and localized to 22q11 by in situ hybridization to metaphase chromosomes. The number of copies of this sequence was determined in CES patients by means of Southern blots and densitometry analysis of autoradiographs. In patients with the supernumerary chromosome, four copies were found, whereas in one patient with a duplication of part of chromosome 22, there were three copies. Therefore, the syndrome results from the presence of either three or four copies of DNA sequences from 22q11; there is no evidence that sequences from other chromosomes are involved. This work demonstrates how DNA sequence dosage analysis can be used to study genetic disorders that are not readily amenable to standard cytogenetic analysis.
Nine related individuals have been identified as being trisomic for the distal part of the long arm of chromosome 15 (15q23 to 15qter). The physical characteristics, especially the facial features, of these nine cases are similar and distinctive. These include: facial asymmetry, down-slanting palpebral fissures, ptosis, prominent nose, long philtrum, down-turned mouth, midline crease in the lower lip, puffy cheeks, and micrognathia. By comparing related individuals with the same translocation, the variability due to different breakpoints can be eliminated. Clinical similarities between unrelated individuals with similar duplicated 15q material, but differing second chromosomes, suggest that the phenotype is due to the extra distal 15q chromosomal material. We conclude that distal 15q trisomy produces a clinically recognizable syndrome.
We describe two patients with acquired idiopathic sideroblastic anemia and a terminal deletion of chromosome No. 11. In spite of the marked chromosomal abnormality neither patient has developed acute leukemia.
Cytogenetic studies of bone marrow specimens from 15 patients with dysmyelopoietic syndrome are presented. The group consists of nine patients with refractory anemia with excess of blasts (RAEB), three patients with chronic myelomonocytic leukemia (CMMoL), and three patients with acquired idiopathic sideroblastic anemia (AISA). None of these patients had a prior history of therapeutic or occupational exposure to potential carcinogenic agents, G(TG)-banding revealed clonal abnormalities in nine of the 15 patients. Five of these patients exhibited one or more of the following cytogenetic abnormalities: 5q deletion, -7, +8, or +21. The AISA group appeared to be unique as chromosome abnormalities were seen in two of the three patients and the clinical course in these patients had been prolonged without progression to acute leukemia. No other clinical correlation could be made in the blast RAEB and CMMoL groups, except for possible survival benefit in patients with normal karyotypes.
Two patients who presented with acute leukemia of Burkitt's cell type are discussed. Although one patient died within four months of diagnosis, the other has maintained a one year clinical complete remission. The clinical and morphologic picture of Burkitt's leukemia is nonspecific and therefore requires complementary studies including cytochemistry, transmission electron microscopy, cell surface markers and cytogenetics studies to establish diagnosis. Serial bone marrow aspirations with marker analyses may detect relapse at an earlier stage than conventional cytology, allowing therapy to be modified prior to overt clinical relapse.
Myelodysplasia and acute nonlymphocytic leukemia following therapy for Hodgkin's disease are observed rather frequently. Herein, we describe a patient with this syndrome treated with prolonged chemotherapy (alone), having a monosomy 7 karyotype. Cytogenetic studies were performed serially during the myelodysplasia preceding overt leukemia. Review of the literature and relevance of these findings are discussed.
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