Preimplantation genetic diagnosis of aneuploidy: were we looking at the wrong chromosomes?
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PURPOSE: Our purpose was to study aneuploidy frequencies of chromosomes 1, 4, 6, 7, 14, 15, 17, 18, and 22 in cleavage-stage embryos. These frequencies were compared to spontaneous abortion data to determine differences in survival rate of their aneuploidies. METHODS: One hundred ninety-four embryos were analyzed with multicolor fluorescence in situ hybridization. Embryos were divided into three maternal age groups: 20 to 34.9 years, (2) 35 to 39.9 years, and (3) 40 years and older. Embryos were also divided into two developmental and morphological groups; arrested and nonarrested embryos. RESULTS: The rate of aneuploidy was 14.51%, 14.10%, and 31.48% for age groups 1, 2, and 3, respectively (P < 0.005). The chromosomes most frequently involved in aneuploidy events were 22, 15, 1, and 17. CONCLUSIONS: The chromosomes most involved in spontaneous abortions are not necessarily the ones causing a decrease in implantation rates with maternal age. Other aneuploidies, such as for chromosomes 1 and 17, may seldom implant or die shortly after implantation. (+info)
Screening for submicroscopic chromosome rearrangements in children with idiopathic mental retardation using microsatellite markers for the chromosome telomeres.
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Recently much attention has been given to the detection of submicroscopic chromosome rearrangements in patients with idiopathic mental retardation. We have screened 27 subjects with mental retardation and dysmorphic features for such rearrangements using a genetic marker panel screening. The screening was a pilot project using markers from the subtelomeric regions of all 41 chromosome arms. The markers were informative for monosomy in both parents at 3661902 loci (40.6%, 95% confidence interval 37.0-44.2%) in the 22 families where DNA was available from both parents. In two of the 27 subjects, submicroscopic chromosomal aberrations were detected. The first patient had a 5-6 Mb deletion of chromosome 18q and the second patient had a 4 Mb deletion of chromosome 1p. The identification of two deletions in 27 cases gave an aberration frequency of 7.5% without adjustment for marker informativeness (95% confidence interval 1-24%) and an estimated frequency of 18% if marker informativeness for monosomy was taken into account. This frequency is higher than previous estimates of the number of subtelomeric chromosome abnormalities in children with idiopathic mental retardation (5-10%) although the confidence interval is overlapping. Our study suggests that in spite of the low informativeness of this pilot screening, submicroscopic chromosome aberrations may be a common cause of dysmorphic features and mental retardation. (+info)
The chromosome 10 monosomy common in human melanomas results from loss of two separate tumor suppressor loci.
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Alteration of chromosome 10 is common in human melanomas and usually entails the loss of an entire chromosome homologue. Although the reasons for monosomy in cancer has remained obscure, one possibility is that multiple tumor suppressor genes residing on this chromosome must be lost in unison during tumor progression, and this is easier to accomplish by chromosome segregation rather than by multiple mutational and/or deletion events. The localization and identification of these genes has been hampered by the monosomy itself, which has resulted in a paucity of small defining deletions in tumors. Here, we have addressed the issue of monosomy in tumor development by using functional complementation mapping to localize and demonstrate the existence of different melanoma suppressor genes on chromosome 10 and assigned each locus a distinct tumorigenic phenotype. We report that a locus on 10q distal to 10q23.1, likely involving the PTEN tumor suppressor, causes a severe reduction in the kinetics of melanoma tumor formation in animals. In contrast, a previously unrecognized region at 10p15.3 has a distinct, but lesser, effect on in vivo melanoma growth. Thus, the loss of both of these regions, which is accomplished by tumor-associated monosomy, provides a significant growth advantage over the individual loss of either region, thereby explaining the monosomy observed in sporadic melanomas. (+info)
CD34(+) acute myeloid and lymphoid leukemic blasts can be induced to differentiate into dendritic cells.
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CD34(+) hematopoietic stem cells from normal individuals and from patients with chronic myelogenous leukemia can be induced to differentiate into dendritic cells (DC). The aim of the current study was to determine whether acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) cells could be induced to differentiate into DC. CD34(+) AML-M2 cells with chromosome 7 monosomy were cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNFalpha), and interleukin-4 (IL-4). After 3 weeks of culture, 35% of the AML-M2 cells showed DC morphology and phenotype. The DC phenotype was defined as upmodulation of the costimulatory molecules CD80 and CD86 and the expression of CD1a or CD83. The leukemic nature of the DC was validated by detection of chromosome 7 monosomy in sorted DC populations by fluorescence in situ hybridization (FISH). CD34(+) leukemic cells from 2 B-ALL patients with the Philadelphia chromosome were similarly cultured, but in the presence of CD40-ligand and IL-4. After 4 days of culture, more than 58% of the ALL cells showed DC morphology and phenotype. The leukemic nature of the DC was validated by detection of the bcr-abl fusion gene in sorted DC populations by FISH. In functional studies, the leukemic DC were highly superior to the parental leukemic blasts for inducing allogeneic T-cell responses. Thus, CD34(+) AML and ALL cells can be induced to differentiate into leukemic DC with morphologic, phenotypic, and functional similarities to normal DC. (+info)
14q32 translocations and monosomy 13 observed in monoclonal gammopathy of undetermined significance delineate a multistep process for the oncogenesis of multiple myeloma. Intergroupe Francophone du Myelome.
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Clonal plasma cells in monoclonal gammopathy of undetermined significance (MGUS) have been shown to bear copy number chromosome changes. To extend our knowledge of MGUS to structural chromosomal abnormalities, we have performed fluorescence in situ hybridization experiments with probes directed to the 14q32 and 13q14 chromosomal regions in 100 patients with either MGUS or smoldering multiple myeloma (SMM). 14q32 abnormalities were observed in at least 46% of patients with MGUS/SMM, with these abnormalities being present in the majority of clonal plasma cells. Whereas t(11;14)(q13;q32) occurs in 15% of MGUS/SMM patients, an incidence similar to that of overt multiple myeloma (MM) patients, translocation t(4;14)(p16;q32) is observed in only 2% of these cases [P = 0.002 for difference with t(11;14)], as compared with 12% in MM patients (P = 0.013). Monoallelic deletions of the 13q14 region were found in 21% of patients, with two types of situations. In half of the evaluable patients, and especially in patients with SMM, the deletion is present in the majority of clonal plasma cells, as in MM, whereas in the other half of the evaluable patients (essentially in MGUS patients), it is observed in subclones only. These data enable us to elaborate a plasma cell oncogenesis model from MGUS to MM. (+info)
Analysis of myelodysplastic syndrome clones arising after multiple myeloma: a case study by correlative interphase cytogenetic analysis.
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BACKGROUND: A patient with multiple myeloma developed myelodysplastic syndrome (MDS). Chromosomal analysis performed after the development of MDS revealed monosomy of chromosome 9 in all the meta-phases. We wished to identify the extent of the clone with the chromosomal abnormality originating from MDS clone. METHODS: A correlative interphase study by fluorescence in situ hybridization (FISH) was performed and we determined whether each lineage of cells obtained the molecular mark. The chromosome 9 classic alpha satellite region DNA was used as a probe for the FISH analysis in smear specimens stained with Wright-Giemsa stain. RESULTS: Erythroblasts, granulocytes and myelocytes had only one signal, whereas myeloma cells showed two to four signals. CONCLUSION: This study visualized the spectrum of MDS clone. The results suggest that the origin of MDS is different from that of multiple myeloma, at least in this case. (+info)
Monosomy 13 is associated with the transition of monoclonal gammopathy of undetermined significance to multiple myeloma. Intergroupe Francophone du Myelome.
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Chromosomal abnormalities are present in most (if not all) patients with multiple myeloma (MM) and primary plasma cell leukemia (PCL). Furthermore, recent data have shown that numerical chromosomal changes are present in most individuals with monoclonal gammopathy of undetermined significance (MGUS). Epidemiological studies have shown that up to one third of MM may emerge from pre-existing MGUS. To clarify further possible stepwise chromosomal aberrations on a pathway between MGUS and MM, we have analyzed 158 patients with either MM or primary PCL and 19 individuals with MGUS using fluorescence in situ hybridization (FISH). Our FISH analyses were designed to detect illegitimate IGH rearrangements at 14q32 or monosomy 13. Whereas translocations involving the 14q32 region were observed with a similar incidence (60%) in both conditions, a significant difference was found in the incidence of monosomy 13 in MGUS versus MM or primary PCL. It was present in 40% of MM/PCL patients, but in only 4 of 19 MGUS individuals. Moreover, whereas monosomy 13 was found in the majority of plasma cells in MM, it was observed only in cell subpopulations in MGUS. It is noteworthy that, in a group of 20 patients with MM and a previous MGUS history, incidence of monosomy 13 was 70% versus 31% in MM patients without a known history of MGUS (P =.002). Thus, this study highlights monosomy 13 as correlated with the transformation of MGUS to overt MM and may define 2 groups of MM with possible different natural history and outcome, ie, post-MGUS MM with a very high incidence of monosomy 13 and de novo MM in which other genetic events might be involved. Serial analyses of individuals with MGUS will be needed to validate this model. (+info)
Paternal sex chromosome aneuploidy as a possible origin of Turner syndrome in monozygotic twins: case report.
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The meiotic or mitotic origin of most cases of Turner syndrome remains unknown, due to the difficulty in detecting hidden mosaicisms and to the lack of meiotic segregation studies. We have had the opportunity to study one pair of monozygotic twins concordant for Turner syndrome of paternal origin. The paternal origin of the single X chromosome was determined by polymerase chain reaction (PCR) amplification. No mosaicism was detected for the X or Y chromosome. In this case, a meiotic error during gametogenesis would be a likely origin of X monosomy. To determine if meiotic errors are more frequent in the father of these monozygotic twins concordant for Turner syndrome of paternal origin, molecular studies in spermatozoa were conducted to analyse sex chromosome numerical abnormalities. A total of 12520 sperm nuclei from the twins' father and 85338 sperm nuclei from eight normal donors were analysed using three-colour fluorescent in-situ hybridization. There were significant differences between the twins' father and control donors for XY disomy (0.22 versus 0.11%, P < 0.001) and total sex chromosome disomy (0.38 versus 0.21%, P < 0.001). These results could indicate an increased tendency to meiotic sex chromosome non-disjunction in the father of the Turner twins. (+info)