The role of the Philadelphia translocation in chronic myeloid leukemia

During the last two decades evidence for a close association between the presence of specific chromosomal abnormalities and the occurrence of several types of cancers and leukemias has accumulated. The Philadelphia (Ph 1) translocation, present in about 90% of the patients with chronic myeloid leukemia (CML), is one of the most typical and best documented examples of such an aberration. Usually this translocation involves chromosome 9 and 22: t(9;22)(q34;q11). The translocation products are designated 9q+ and 22q-. Variant translocations involving an array of translocation sites different from 9 have been described as well, but chromosome 22 is always involved. So far, no clear indications were found for the possible role played by this highly specific chromosomal aberration in the etiology of CML. Moreover, results concerning the exact nature of the Ph1 translocation, obtained by different investigators using different techniques, appeared to be contradictory. In this thesis the application of somatic cell hybridization and gene segregation analyses to these questions has been described. Rodent cells (fibroblasts) were fused with human Ph1 positive leucocytes and, subsequently, hybrid cell 1 ines were isolated. These hybrids appeared to segregate human chromosomes, including the Ph1 translocation products. The segregation of genes, previously assigned to the regions of the chromosomal breakpoints, was studied together with the segregation of the relevant human (translocation) chromosomes. Several genes on chromosome 22 were found to be translocated to the 9q+ chromosome which confirmed, on a molecular level, the translocation of chromosome 22 materia] to chromosome 9. Another gene on chromosome 22 (immunoglobulin A 1 ight chain) stayed on the Ph1 chromosome (22q-). One gene on chromosome 9 (c-abl) appeared to be translocated to 22q-. This latter result provided unequivocal evidence for reciprocity of the Ph 1 translocation. No apparent differences in chromosomal breakpoints could be revealed in the different CML patients used for analysis and no evidence was found for loss of chromosomal material {genes) as a result of the Ph 1 translocation. The clonal origin of the Ph 1 translocation in CML was confirmed using a chromosome 9 encoded polymorphic enzyme (AKI)

A long-lasting, complete hematologic and cytogenetic remission of chronic myelogenous leukemia after treatment with busulfan alone

A 44-year-old man suffering from cytogenetically and molecularly proven Philadelphia translocation-positive chronic myelogenous leukemia in chronic phase was treated with busulfan for 18 months and studied during a follow-up period of 13 years. Hematologically and cytogenetically, he attained a continuing complete remission, although at one point (9.5 years) at least, after attaining complete remission molecular analysis indicated the presence of minimal residual disease

Isolation of anonymous, polymorphic DNA fragments from human chromosome 22q12-qter

A series of 195 random chromosome 22-specific probes, equivalent to approximately 1% of the size of this chromosome, have been isolated from a chromosome 22-specific bacteriophage lambda genomic library. These probes were mapped to four different regions of chromosome 22 on a panel of five somatic cell hybrids. Restriction fragment length polymorphisms were detected by 28 of the probes mapping to 22q12-qter. Evolutionarily conserved sequences in human, mouse, and Chinese hamster DNA were detected by 12% of the isolated probes

Fluorescence in situ hybridization-based approaches for detection of 12p overrepresentation, in particular i(12p), in cell lines of human testicular germ cell tumors of adults

Overrepresentation of the short arm of chromosome 12 is frequently detected in human testicular germ cell tumors of adolescents and adults (TGCT). This overrepresentation mostly results from the formation of an isochromosome i(12p). Whether the overrepresentation consistently involves the complete 12p arm including the centromere is still unclear. We studied five TGCT-derived cell line

High-throughput analysis of subtelomeric chromosome rearrangements by use of array-based comparative genomic hypridization

Telomeric chromosome rearrangements may cause mental retardation, congenital anomalies, and miscarriages. Automated detection of subtle deletions or duplications involving telomeres is essential for high-throughput diagnosis, but impossible when conventional cytogenetic methods are used. Array-based comparative genomic hybridization (CGH) allows high-resolution screening of copy number abnormalities by hybridizing differentially labeled test and reference genomes to arrays of robotically spotted clones. To assess the applicability of this technique in the diagnosis of (sub)telomeric imbalances, we here describe a blinded study, in which DNA from 20 patients with known cytogenetic abnormalities involving one or more telomeres was hybridized to an array containing a validated set of human-chromosome–specific (sub)telomere probes. Single-copy-number gains and losses were accurately detected on these arrays, and an excellent concordance between the original cytogenetic diagnosis and the array-based CGH diagnosis was obtained by use of a single hybridization. In addition to the previously identified cytogenetic changes, array-based CGH revealed additional telomere rearrangements in 3 of the 20 patients studied. The robustness and simplicity of this array-based telomere copy-number screening make it highly suited for introduction into the clinic as a rapid and sensitive automated diagnostic procedure

Comparative genomic hybridization of germ cell tumors of the adult testis: Confirmation of karyotypic findings and identification of a 12p- amplicon

Comparative genomic hybridization (CGH) was carried out on 15 primary testicular germ cell tumors (TGCT) of adolescents and adults and two metastatic residual tumors after chemotherapeutic treatment. The results were compared with karyotypic data obtained form the same tumor specimens after direct harvesting of metaphases or short-term in vitro culture. Both techniques revealed that the most consistent abnormality in primary TGCT is gain of 12p-sequences. Although in most cases over-representation of the complete short arm was observed, CGH revealed a specific amplification of 12p11.1-p12.1 region in two independent primary tumors. In addition, loss of (parts of) chromosome 13 (always involving q31-qter), and gain of (parts of) chromosome 7 (mostly involving q11), (parts of) chromosome 8, and the X chromosome were detected in more than 25% of the tumors by this latter technique. Loss of 6q15-q21 in both re

ベルト・モリゾと日本美術(1) : 扇・団扇のジャポニスムから1890年ビングの「日本版画展」まで

textabstractA human genomic fragment comprising the cellular retinoic acid binding protein (CRABP) gene was isolated. By using a panel of somatic cell hybrids, this gene could be assigned to human chromosome 15. Subsequently, a possible involvement of the CRABP gene in translocation (15;17) (q22;q11) positive acute promyelocytic leukemia (APL) was investigated. Although transposition of the CRABP gene could be demonstrated, we did not observe any gross CRABP rearrangement in a series of primary APL patients, nor in the acute myeloblastic leukemia cell line HL-60. Thus, the observed lack of CRABP expression in these leukemic cells may not be caused by disruption of its gene. CRABP maps to the region 15q22-qter

Multiclonal complexity of pediatric acute lymphoblastic leukemia and the prognostic relevance of subclonal mutations

Genomic studies of pediatric acute lymphoblastic leukemia (ALL) have shown remarkable heterogeneity in initial diagnosis, with multiple (sub)clones harboring lesions in relapse-associated genes. However, the clinical relevance of these subclonal alterations remains unclear. We assessed the clinical relevance and prognostic value of subclonal alterations in the relapse-associated genes IKZF1, CREBBP, KRAS, NRAS, PTPN11, TP53, NT5C2, and WHSC1 in 503 ALL cases. Using molecular inversion probe sequencing and breakpoint-spanning polymerase chain reaction analysis we reliably detected alterations with an allele frequency below 1%. We identified 660 genomic alterations in 285 diagnostic samples of which 495 (75%) were subclonal. RAS pathway mutations were common, particularly in minor subclones, and comparisons between RAS hotspot mutations revealed differences in their capacity to drive clonal expansion in ALL. We did not find an association of subclonal alterations with unfavorable outcome. Particularly for IKZF1, an established prognostic marker in ALL, all clonal but none of the subclonal alterations were preserved at relapse. We conclude that, for the genes tested, there is no basis to consider subclonal alterations detected at diagnosis for risk group stratification of ALL treatment