Variant Ph translocations in chronic myeloid leukemia

Variant translocations were found in eight of 142 consecutive patients with Ph-positive, chronic myeloid leukemia encountered in our laboratory during the last decade. Two patients had simple, two-way variant translocations: t(17;22)(p13;q11) and t(16;22)(q24;q11). Both of these patients had an additional translocation involving chromosomes #9: t(7;9)(q22;q34) and t(9;17)(q34;q21), respectively. Complex variant translocations were found in four cases: t(2;9;22)(p23q12;q34;q11), t(3;9;22)(p21;q34;q11), t(9;12;22)(q34;q13;q11q13), and t(13;17;22)(p11;p11q21;q11). In two cases, the only discernable cytogenetic aberration was del(22)(q11). A review of the chromosomal breakpoints involved in this series and in 185 cases of variant Ph translocations previously reported in the literature reveals that a disproportionately large number of breakpoints are located in light-staining regions of G-banded chromosomes. Furthermore, the breakpoints in simple variant translocations are more often located in terminal chromosomal regions, whereas, the breakpoints in complex translocations typically affect nonterminal bands. No obvious correlation was detected between variant Ph translocation breakpoints and either fragile sites, oncogene locations, or consistent chromosome breakpoints in other malignancies.     

No difference in expression of chromosomal fragile sites in patients with solid malignant tumours and normal controls

The frequency and distribution of rare and common chromosomal fragile sites in metaphases derived from peripheral lymphocytes were compared in 26 patients with malignant solid tumours and 24 normal controls. In order to avoid bias in evaluation, the identity of each individual as patient or control was disclosed only after the study was completed. Rare heritable folic acid inducible fragile sites were found in five patients (2q13; 6p23; 8q22; 16p12) and two controls (8q22). Common fragile sites were present in 21 of 26 patients and in 19 of 24 controls. These differences are statistically not significant in the Fisher test. We conclude that the expression of fragile sites does not indicate a predisposition for solid tumours.     

Translocation (8;21) and its variants in acute nonlymphocytic leukemia. The relative importance of chromosomes 8 and 21 to the genesis of the disease

Chromosome analysis was performed in 25 patients with acute nonlymphocytic leukemia (ANLL), mostly of the M2 type. Eighteen had the standard translocation, t(8;21)(q22;q22), four had complex translocations involving 1p36, 11p13, 17p11, and 17p23, respectively, with chromosomes 8 and 21, and the remaining three patients had simple translocations, one with t(3;21)(p14;q22) and two with t(16;21)(p11;q22), without involving chromosome 8. Chromosome abnormalities additional to t(8;21) and its variants that were most frequently observed were -X, -Y, and del(9). Complex translocations are thought to be derived from the standard translocation and to be essentially similar in nature. The finding that chromosome 21 was involved in all of the standard, simple, and complex translocations, and that chromosome 8 was not involved in simple variants suggest a greater weight of chromosome 21 in the relative importance of the two chromosomes to the genesis of ANLL.     

Chromosomal fragile sites and relationship between genetic predisposition to small cell lung cancer.

Fragile sites are non-staining gaps and breaks on mammalian chromosomes. Several investigators have pointed out that these sites may act as factors that predispose to specific chromosomal rearrangements that are present in some cancer cases. The expression of common fragile sites induced by aphidicolin (Apc) was evaluated on prometaphase chromosomes obtained from the peripheral blood lymphocytes of 15 patients with lung cancer, 20 of their clinically healthy family members, and 20 age-matched normal controls. As a result of cytogenetic evaluation carried out by the High Resolution Banding (HRB) technique, 1q21, 2q33, 3p14, 7q32, 13q13, 16q23, 17q21, and 22q12 are defined as fragile sites in patients and relatives. The rate of total fragile sites and 2q33, 3p14, and 16q23 are statistically significant in both patients and relatives when compared with the control group. Therefore, our results showed that common fragile sites might be unstable factors in the human genome and they can be used as suitable markers for genetic predisposition to lung cancer.     

Normal blood lymphocytes from patients with adipose tissue tumors with rearrangements at 12q13-q14 do not express the fragile site fra(12)(q13.1)

An association between chromosomal fragile sites and cancer-specific breakpoints has been found to be statistically significant. Cancer patients have been shown to be carriers of fragile sites in chromosome regions involved in rearrangements in malignant cells. Based on these observations it has been hypothesized that fragile sites may be involved in the pathogenesis of human tumors. We have recently described a new recurrent cancer breakpoint at chromosomal region 12q13-q14 in adipose tissue tumors. The possible involvement in these tumors of the rare folate-sensitive fragile site 12q13.1 has been investigated in PHA-stimulated peripheral blood cells from three patients carrying the t(12;16)(q13;p11) in their liposarcoma cells and one patient with the t(3;12)(q28;q14) in his lipoma cells. No expression of the fragile site 12q13.1 could be detected in the blood lymphocytes of any of the patients. The involvement of the fragile site 12q13.1 in the pathogenesis of adipose tissue tumors with a 12q13-q14 breakpoint remains to be established.     

Fragile sites, Alzheimer's disease, and aging.

The fragile site expression under conditions of folate deprivation was compared in the chromosomes from 5 Alzheimer's disease (AD) female patients, 5 healthy elderly females and 5 healthy young females. Although different fragile sites were observed in the three groups, nevertheless, more similarities were found between the AD patients and elderly normal donors. The only fragile site common to all groups was 3p14. This site was the most frequent in the young donors group. In both AD and elderly control groups we observed a higher frequency of fragility in 6p21, but not in the young controls. Other interesting fragility points observed in these two groups were: 6q21 and 14q24 (in the AD patients) and 9q13, 14q24 and 17q21 (in the healthy aged). 6p21 and 17q21 have been proposed as 'new' fragile sites. We confirm the existence of these fragile sites and comment that in these bands the genes MTBT2 and MTBT1, which are microtubule (beta) associated protein tau-like and tau 1, respectively, are mapped. The tau protein is a component of paired helical filaments which accumulate in degenerating neurons in the brain of patients with AD and with less intensity of normal elderly individuals.     

Evaluation of paediatric osteosarcomas by classic cytogenetic and CGH analyses.

Classic cytogenetic and comparative genomic hybridisation (CGH) data on osteosarcomas have been reported extensively in the literature. However, the number of paediatric osteosarcoma cases studied below the age of 14 years remains relatively small. This study reports four new cases of paediatric osteosarcoma in patients aged 3 to 13 years, evaluated by classic cytogenetics and CGH analyses. Clonal chromosomal alterations were detected in all the cases and included structural rearrangements at 1p11-13, 1q11, 4q27-33, 6p23-25, 6q16-25, 7p13-22, 7q11-36, 11p10-15, 11q23, 17p11.2-13, 21p11, and 21q11-22. The CGH analysis revealed recurrent gains at 1p, 4q, 17p, and 21q and losses at 3q and 16p. Five amplification sites were observed at 1q11-23, 6p21, 8q13, 8q21.3-24.2, and 17p. The data are discussed and compared with other cytogenetic reports in the literature.     

Aphidicolin-sensitive specific common fragile sites: A biomarker of exposure to pesticides

In this work, we analyzed the aphidicolin-sensitive common fragile sites in seven females and four males occupationally exposed to pesticides and in ten controls. The same males had been monitored one year earlier in a previous study by the same authors. Results showed enhanced expression in exposed subjects at eight bands, namely, 6q25, 7p22, 7q22, 7q32, 13q14, 14q24, 16q22, and 16q23. Most of these bands were fragile sites andbreakpoints involved in chromosome rearrangements found in hematopoietic tumors. Moreover, six of these bands were already detected, with enhanced expression, in the first monitoring carried out on male subjects. These results indicated that fragile sites analysis is a reproducible cell response to human exposure to pesticides. Environ. Mol. Mutagen. 29:250-255, 1997 © 1997 Wiley-Liss, Inc.     

Balanced double complex translocations [46,XX,t(1p;6p;7p;3q;11p)(11q;22p;21q)] in an infant with multiple congenital anomalies

We describe a 1-month-old female infant with balanced double complex translocations [46,XX,t(1p;6p;7p;3q;11p) (11q;22p;21q)]. She had a multiple congenital anomalies syndrome of microcephaly, unilateral corneal staphyloma, hypoplastic thumbs, ectrodactyly of the right foot, brachydactyly of the left third toe, and syndactyly between the left fourth and the fifth toes. The complex chromosome rearrangements of the patient involve 8 breakpoints, the greatest number of breakpoints in complex chromosome rearrangements of humans known to us. The 8 breakpoints are 1p22, 3q27, 6p21, 7p15, 11p15, 11q11, 21q11, and 22p11. These are not related to any confirmed fragile sites. These double complex translocations seemed to have occurred de novo.     

Distamycin A-inducible fragile sites and cancer proneness

To determine the baseline frequency of autosomal rare fragile sites in cancer patients, we conducted a population cytogenetic study of 370 patients with leukemias, solid tumors, and other neoplastic disorders. Twenty carriers of rare fragile sites were detected in this patient group. The rare autosomal fragile sites were at fra(8)(q24), fra(11)(p15), fra(16)(p12.1), fra(16)(q22), and fra(17)(p12). All of these fragile sites were found to be distamycin A inducible. Compared with a population incidence in healthy subjects (44 of 845, 5.21%), the overall incidence of distamycin A-inducible fragile sites was not higher in the patient group (20 of 370, 5.41%). Analysis of these individual fragile sites and particular diseases, however, suggests that the distamycin A-inducible fragile sites may play a role in the etiology of leukemia, myeloproliferative disorders, and benign tumors.     

Introduction to living history–biography of arthur barclay chapman

We describe a 1-month-old female infant with balanced double complex translocations [46,XX,t(1p;6p;7p;3q;11p) (11q;22p;21q)]. She had a multiple congenital anomalies syndrome of microcephaly, unilateral corneal staphyloma, hypoplastic thumbs, ectrodactyly of the right foot, brachydactyly of the left third toe, and syndactyly between the left fourth and the fifth toes. The complex chromosome rearrangements of the patient involve 8 breakpoints, the greatest number of breakpoints in complex chromosome rearrangements of humans known to us. The 8 breakpoints are 1p22, 3q27, 6p21, 7pl5, 1lp15, 11q11, 21q11, and 22p11. These are not related to any confirmed fragile sites. These double complex translocations seemed to have occurred de novo.     

Heritable fragility at 11q13 and 12q13

The chromosomes of two mentally retarded probands were investigated because they were suspected of having the fragile X syndrome. However two other fragilities were detected. In one patient a fra(11)(q13) was found and in the other a fra(12)(q13). Family studies revealed that both fragile sites were real heritable ones. Besides these two heritable fragile sites, the common fragile site at 3p14 was frequently observed. The effects of BUdR, FUdR and methotrexate on the frequency of the three fragilities were studied. The two heritable fragile sites differed from the common fragile site at 3p14 with respect to their inducibility by FUdR and methotrexate.     

Nonrandom karyotypic features in basal cell carcinomas of the skin.

Cytogenetic analysis of short-term cultured 44 basal cell carcinomas (BCC) revealed clonal karyotypic abnormalities in 38 tumors. Relatively complex karyotypes (at least four structural and/or numerical changes per clone) with unbalanced structural as well as numerical aberrations were found in eight (approximately 21%) of the BCC, while the remaining BCC (79%) had simple karyotypes (1 to 3 aberrations per clone). Numerical changes only were found in 16 tumors, 15 BCC displayed both numerical and structural aberrations, and the remaining 7 BCC showed only structural aberrations. Extensive intratumoral heterogeneity, in the form of cytogenetically unrelated clones, was found in 21 tumors, whereas related subclones were present in 10 tumors. In order to obtain an overall karyotypic picture in BCC, the findings of our previously published 25 BCC have been reviewed. Our combined data indicate that BCC are characterized by nonrandom karyotypic patterns. A large subset of BCC is characterized by nonrandom numerical changes, notably, +18, +X, +7, and +9. Structural rearrangements often affect chromosomes 1, 4, 2, 3, 9, 7, 16, and 17. A number of chromosomal bands are frequently involved, including 9q22, 1p32, 1p22, 1q11, 1q21, 2q11, 4q21, 4q31, 1p36, 2q37, 3q13, 7q11, 11p15, 16p13, 16q24, 17q21, and 20q13. When the genomic imbalance is assessed, it has been shown that several chromosome segments are repeatedly involved in losses, namely loss of the distal part of 6q, 13q, 4q, 1q, 8q, and 9p. A correlation analysis between the karyotypic patterns and the clinico-histopathologic parameters has been undertaken in the 44 BCC of the present series. The cytogenetic patterns show a significant correlation with tumor status (P=.025), that is, that cytogenetically more complex tumors are also those clinically the most aggressive. Also, the frequency of cytogenetically unrelated clones is significantly higher in recurrent BCC than that in primary lesions (P=.05). No clear-cut association has been found between the karyotypic patterns and histologic subtypes or tumor sites.     

Chromosomal abnormalities in leiomyosarcomas.

Thirty-eight tumors from 30 patients diagnosed as leiomyosarcoma were cytogenetically assessed after short term culture. The specimens were obtained from the retroperitoneum, gastrointestinal tract, and extremities. Chromosomal abnormalities were present in 18 tumors from 13 patients; 15 tumors had clonal changes, whereas 3 tumors had numerous nonclonal changes. Ten tumors from 10 patients had normal karyotypes and no results were obtained in 10 other tumors from 7 patients. Of the tumors with clonal chromosomal aberrations, 4 had near-diploid (3 hypo- and one hyperdiploid) modes, 8 were polyploid, and 3 were bimodal. No specific karyotypic change appeared to characterize the leiomyosarcomas, although involvement of some chromosomes appeared more frequent than others. A comparison of our findings with those reported in the literature revealed certain consistent structural rearrangements involving chromosomes 1, 7, 10, 13, and 14 at bands 1p36, 1p32, 1p13, 1q32, 7p11.1-p21, 7q32, 10q22, 13q14, and 14p11, respectively. Other bands less frequently rearranged were 3p13-p22, 3q21, 4q13-q23, 6q15-q21, 7q11.2-q22, 12q13-q14, 17q12-q25, 19q13.3-q13.4, and 20q12-q13.1. Numerical changes included recurrent loss of chromosomes 4, 9, 14, 15, 16, 18, 21, and 22. Identification of the abnormalities of these chromosomes is important in that it may predict the existence of oncogenes, tumor suppressor genes, and/or growth factor genes at these sites. Subsequent molecular analysis might then lead to the identification of the genes involved and ultimately to a better understanding of the pathogenesis of leiomyosarcomas.     

Definition of a new entity of malignant extragonadal germ cell tumors

Two malignant extragonadal germ cell tumors are reported, histologically classified as immature teratomas, having pseudodiploid karyotypes with complex structural rearrangements but lacking isochromosome 12p or other rearrangements involving 12p. The absence of 12p material in structural rearrangements was confirmed by chromosome painting. In the two tumors the following common chromosomal breakpoints were found: 6p21, 6p22, 6q23, and 11q13. Exactly the same chromosomal regions, 6p22::6q23 and 6p21::11q13, were involved in fusions. The two tumors belong to a new entity of extragonadal immature teratomas of adults which may be located in the retroperitoneum and posterior mediastinum and are prone to blood borne metastasis.     

Fragile sites: overview, occurrence in acute nonlymphocytic leukemia and effects of caffeine on expression

Interest has recently grown in the possible role of chromosomal fragile sites as factors predisposing to chromosome rearrangements characteristic of specific human cancers. Data from two series of experiments relating to this hypothesis are presented. First, the effects of caffeine and theophylline on expression of the fragile X and common fragile sites was studied in lymphocytes from three subjects. Caffeine and theophylline did not enhance fragile X expression under the conditions employed but did greatly enhance expression of the common fragile sites. Second, three patients with acute nonlymphocytic leukemia-M4 and inv(16)(p13q22) in leukemic cells were tested for the presence of fra(16)(q22) in normal cells. The fragile site was not seen in any of the patients in this study.     

Parental origin and mechanisms of formation of cytogenetically recognisable de novo direct and inverted duplications

Cytogenetic, FISH, and molecular results of 20 cases with de novo tandem duplications of 18 different autosomal chromosome segments are reported. There were 12 cases with direct duplications, three cases with inverted duplications, and five in whom determination of direction was not possible. In seven cases a rearrangement between non-sister chromatids (N-SCR) was found, whereas in the remaining 13 cases sister chromatids (SCR) were involved. Paternal and maternal origin (7:7) was found almost equally in cases with SCR (3:4) and N-SCR (4:3). In the cases with proven inversion, there was maternal and paternal origin in one case each. Twenty three out of 43 cytogenetically determined breakpoints correlated with common or rare fragile sites. In five cases, including all those with proven inverse orientation, all breakpoints corresponded to common or rare fragile sites. In at least two cases, one with an interstitial duplication (dup(19)(q11q13)) and one with a terminal duplication (dup(8) (p10p23)), concomitant deletions (del(8) (p23p23.3) and del(19)(q13q13)) were found.     

Noninvolvement of chromosome 16 in karyotype evolution of acute myeloid leukemia in a patient with a heritable fragile site on 16q22

A fragile site on the long arm of chromosome #16 (q22) was detected in a 24-year-old man with pancytopenia. During the course of the disease he developed an inverted duplication of region q11-12 of chromosome #1 and a translocation between chromosomes #9 and #13: t(9;13)(p22;q32). These abnormalities, as well as an additional iso-like marker chromosome that consisted of one normal 9p and the abnormal 9p arm, were detected in Epstein-Barr nuclear antigen-positive B-cell cultures. Two years later, evolution of the abnormal clone with loss of chromosome #7 and, subsequently, chromosome #22 occurred in connection with development of acute myeloid leukemia. Although the heritable fragile site on chromosome #16 was present in all cell populations investigated, it was not involved in the evolution of the abnormal karyotype. This fragile chromosome #16 also was found in 4 of 11 family members in whom chromosome analysis was performed, thus suggesting this aberration was inherited in a dominant autosomal pattern. The incidence of the heritable fragile site in normal and leukemic cells of the patient, as well as stimulated blood cultures of his relatives, are reported. In addition, the possible relationship between this constitutional chromosome breakage syndrome and the occurrence of leukemia is analyzed.     

Common fragile sites: their prevalence in subjects with constitutional and acquired chromosomal instability

Chromosomal fragile sites that are inducible by methotrexate and aphidicolin are frequent in the human population. To assess the frequency and distribution of these common fragile sites, we performed a cytogenetic survey on lymphocytes from subjects known to be particularly prone to breakage because of constitutional chromosomal instability, the possession of a rare fragile site, or Fanconi anemia. Furthermore, a group of cancer patients was included in this study in view of possible acquired chromosomal instability. Lymphocyte chromosomes from several healthy donors were analyzed under identical conditions. We found that methotrexate- and aphidicolin-induced fragile sites are widespread in the general population, showing a similar breakpoint distribution. Ten fragile sites (3p14, 16q23, 2q32, 6q25, 4p16, 4q31, 14q24, 1p31, 20p12, 7q21) were observed in at least 40% of the individuals among the different groups. Our data point out a significantly increased breakage induced by aphidicolin in lymphocytes from cancer patients and, to a lesser extent, from rare fragile sites carriers. These results suggest that common fragile sites are enhanced in some constitutional and acquired conditions.     

Molecular cytogenetic characterization of non-Hodgkin lymphoma cell lines.

Spectral karyotyping (SKY) and comparative genomic hybridization (CGH) have greatly enhanced the resolution of cytogenetic analysis, enabling the identification of novel regions of rearrangement and amplification in tumor cells. Here we report the analysis of 10 malignant non-Hodgkin lymphoma (NHL) cell lines derived at the Ontario Cancer Institute (OCI), Toronto, designated as OCI-Ly1, OCI-Ly2, OCI-Ly3, OCI-LY4, OCI-Ly7, OCI-Ly8, OCI-Ly12, OCI-Ly13.2, OCI-Ly17, and OCI-Ly18, by G-banding, SKY, and CGH, and we present their comprehensive cytogenetic profiles. In contrast to the 52 breakpoints identified by G-banding, SKY identified 87 breakpoints, which clustered at 1q21, 7p15, 8p11, 13q21, 13q32, 14q32, 17q11, and 18q21. G-banding identified 10 translocations, including the previously described recurring translocations, t(8;14)(q24;q32) and t(14;18)(q32;q21). In contrast, SKY identified 60 translocations, including five that were recurring, t(8;14)(q24;q32), t(14;18)(q32;q21), t(4;7)(p12;q22), t(11;18)(q22;q21), and t(3;18)(q21;p11). SKY also identified the source of all the marker chromosomes. In addition, 10 chromosomes that were classified as normal by G-banding were found by SKY to be rearranged. CGH identified seven sites of high-level DNA amplification, 1q31-32, 2p12-16, 8q24, 11q23-25, 13q21-22, 13q32-34, and 18q21-23; of these, 1q31-32, 11q23-25, 13q21-22, and 13q32-34 have previously not been described as amplified in NHL. This comprehensive cytogenetic characterization of 10 NHL cell lines identified novel sites of rearrangement and amplification; it also enhances their value in experimental studies aimed at gene discovery and gene function.