Pre-B cell leukemia associated with chromosome translocation 1;19.
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Chromosome banding studies on 60 children with acute lymphocytic leukemia (ALL), including "null," pre-B, B, and T cell phenotypes, were performed. In 4 of 17 patients with pre-B cell ALL, we noted a previously undescribed chromosome translocation, t(1;19)(q23;q13). This translocation was not found in patients with "null" cell, B cell, or T cell ALL. Since each patient with the 1;19 translocation experienced early treatment failure, t(1;19)(q23;q13) may mark a subgroup of patients with pre-B cell ALL who have an especially poor prognosis. (+info)
Linkage analysis of myotonic dystrophy and sequences on chromosome 19 using a cloned complement 3 gene probe.
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Variations in DNA sequence generate polymorphisms which can be followed through families. A cloned gene specific probe for human complement 3 (C3) was hybridised to DNA samples digested with restriction endonucleases. The C3 probe detects several restriction fragment length polymorphisms (RFLPs) that occur frequently in the general population. These DNA alleles can be readily used in linkage analyses of loci on chromosome 19, since most families studied are informative. The inheritance of one such polymorphism was followed through myotonic dystrophy families. The segregation data for both the C3 protein polymorphism and the C3 RFLP support the linkage of myotonic dystrophy (DM) and C3. (+info)
Possible specific chromosome change in prolymphocytic leukemia.
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The chromosomes of unstimulated and stimulated blood lymphocytes from 5 cases with B-cell prolymphocytic leukemia (PLL) were examined following the use of polyclonal B-cell activators (PBA). Banding techniques revealed a common and specific chromosome abnormality to be present in each of the cases, which was due to a translocation between chromosomes 6 and 12 (t(6;12)(q15;p13]. The fact that this specific chromosome change has not been reported in other lymphoproliferative disorders may indicate that PLL is a distinct clinical entity and different from other lymphoproliferative disorders, whether it occurs de novo or complicates chronic lymphocytic leukemia (CLL). (+info)
Somatic cell genetics of adenosine deaminase expression and severe combined immunodeficiency disease in humans.
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The somatic cell hybrid method has been used to study the number and different types of human genes involved in the expression of adenosine deaminase (ADA; adenosine aminohydrolase, EC 3.5.4.4) in normal cells and cells from a patient with ADA-deficient severe combined immunodeficiency disease (SCID). Genetic and biochemical characterization of ADA in SCID and the ADA tissue-specific isozymes in normal human cells indicates that additional genes, besides the ADA structural gene on chromosome 20, are involved in ADA expression. Human chromosome 6 encodes a gene, ADCP-1, whose presence is necessary for the expression of an ADA-complexing protein in human-mouse somatic cell hybrids [Koch, G. & Shows, T. B. (1978) Proc. Natl. Acad. Sci. USA 75, 3876-3880]. We report the identification of a second gene, ADCP-2, on human chromosome 2, that is also involved in the expression of the ADA-complexing protein. The data indicate that these two ADCP genes must be present in the same cell for that cell to express the complexing protein. Human-mouse somatic cell hybrids, in which the human parental cells were fibroblastss from an individual with ADA-deficient SCID, also required human chromosomes 2 and 6 to express the ADA-complexing protein, indicating that neither ADCP-1 nor ADCP-2 is involved in the ADA deficiency in SCID. The SCID-mouse hybrid cells expressed no human ADA even when human chromosome 20 had been retained. The deficiency of human ADA in these hybrids maps to human chromosome 20, and therefore is not due to the repression or inhibiton of ADA or its product by unlinked genes or gene products. We propose that the expression of the polymeric ADA tissue isozymes in human cells requires at least three genes: ADA on chromosome 20, ADCP-1 on chromosome 6, and ADCP-2 on chromosome 2. A genetic scheme is presented and the different genes involved in ADA expression and their possible functions are discussed. (+info)
Deletion of the long arm of chromosome 20 [del(20)(q11)] in myeloid disorders.
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Detailed clinical and cytogenetic studies were performed in five patients who had abnormal hematopoiesis and an acquired deletion of an F-group chromosome. Cytogenetic analyses, with banding techniques, of cells from bone marrow, spleen, or unstimulated peripheral blood showed a partial deletion of the long arm of one chromosome 20 [del(20)(q11)] in all five patients. Three patients had myeloproliferative disorders of uncertain classification, the fourth had possible preleukemia, and the fifth had acute myelomonocytic leukemia. Although the five cases showed certain similarities, the clinical and hematologic findings seen with the 20q- abnormality were not specific. None of the patients showed evidence of polycythemia vera or idiopathic acquired refractory sideroblastic anemia, two diseases previously associated with the 20q-. Our studies indicate that the 20q- abnormality is not limited to diseases primarily affecting erythropoiesis but that it can be found in the broader spectrum of myeloid disorders. In polycythemia vera, the 20q- has sometimes been regarded as a possible result of previous therapy with cytotoxic agents; however, four of our patients were untreated when the deletion was first noted. (+info)
Length heteromorphisms of fluorescent (f) and non-fluorescent (nf) segments of human Y chromosome: classification, frequencies, and incidence in normal Caucasians.
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Sixty normal male Caucasians were selected to study the length of the Y chromosome. QFQ banding was performed. Chromosomes 19 and 20 (F) and Y were measured directly from the film. Y/F, f/F, and nf/F indices (f = fluorescent; nf = non-fluorescent segment) were determined. The length of the Y chromosome was classified into 5 groups; very small, small, average, large, and very large with Y/F indices of less than 0.8, 0.81--0.94, 0.95--1.09, 1.1--1.23, and greater than 1.23, respectively. The frequencies of Y/F indices for these groups were 0 (0%), 9 (15.0%), 40 (66.7%), 8 (13.3%), and 3 (5.0%), respectively. The most frequent class was 0.95--1.09 and was defined as the 'average' Y/F index for the human Y chromosome. The variation in the total length of the Y chromosome was accounted for by variations in the length of the non-fluorescent as well as the fluorescent segments. No relation between f and nf segments was observed. The mean Y/F, f/F, and nf/F indices were 1.022, 0.441, and 0.574, respectively. (+info)
Prenatal detection of Turner's syndrome in conjunction with trisomy 20 mosaicism (45,X/46, X, +0).
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A case of Turner's syndrome, detected antenatally and complicated by the finding of trisomy 20 mosaicism in 50% of cells from each of two amniotic fluid cultures, is described. Cultures from seven fetal tissues in the subsequent abortus showed a predominance of 45,X cells, but nevertheless suggested the existence of a very low level of trisomy 20 mosaicism in three fetal tissues. The diagnostic dilemma in interpreting trisomy 20 mosaicism is discussed. (+info)
Familial pericentric inversion 19.
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Several members in two families were found to have a pericentric inversion of chromosome 19. A review of four previous cases, together with those reported here, suggests that inversion of chromosome 19 is not related to the phenotypic features of the probands. Furthermore, there has been no report of an affected subject resulting from a duplication deficiency product of inverted chromosome 19 among the offspring of inversion heterozygotes. The suggested association of aneuploidy in the inversion carriers is also discussed. (+info)