Cytogenetic analysis of 52 colorectal carcinomas--non-random aberration pattern and correlation with pathologic parameters

Cytogenetic analysis of short-term cultures from 52 colorectal carcinomas revealed a normal karyotype in 13 and clonal chromosome aberrations in 39 tumors. In the abnormal group, 13 tumors had simple numerical changes only, whereas 26 had at least one structural rearrangement with or without concomitant numerical changes. The most common numerical abnormalities were, in order of decreasing frequency, +7, -18, -Y, +8, +13 and -14. The most common structural rearrangements affected, again in order of decreasing frequency, chromosomes 8, 1, 6, 7, 17, 3, 11, 13, 14, 16, 2 and 10. The chromosome bands most frequently involved in the structural changes were 8q10, 17p11, 11q13, 8p11, 6q21, 7p15, 7q36, 12q13, 13q10, and 16q13. The most frequent genomic imbalances brought about by the structural rearrangements were losses from chromosome arms 8p, 1p, 6q, 17p, 7p, and 16q, as well as gains of 7q, 8q, 13q, and 11q. A statistically significant (p < 0.05) correlation between the karyotypic pattern and tumor grade was found, with the poorly differentiated carcinomas generally having more massive chromosomal abnormalities.     

Karyotypic abnormalities in tumours of the pancreas

Short-term cultures from 20 pancreatic tumours, three endocrine and 17 exocrine, were cytogenetically analysed. All three endocrine tumours had a normal chromosome complement. Clonal chromosome aberrations were detected in 13 of the 17 exocrine tumours: simple karyotypic changes were found in five carcinomas and numerous numerical and/or structural changes in eight. When the present findings and those previously reported by our group were viewed in conjunction, the most common numerical imbalances among the 22 karyotypically abnormal pancreatic carcinomas thus available for evaluation turned out to be, in order of falling frequency, -18, -Y, +20, +7, +11 and -12. Imbalances brought about by structural changes most frequently affected chromosomes 1 (losses in 1p but especially gains of 1q), 8 (in particular 8q gains but also 8p losses), and 17 (mostly 17q gain but also loss of 17p). Chromosomal bands 1p32, 1q10, 6q21, 7p22, 8p21, 8q11, 14p11, 15q10-11, and 17q11 were the most common breakpoint sites affected by the structural rearrangements. Abnormal karyotypes were detected more frequently in poorly differentiated and anaplastic carcinomas than in moderately and well differentiated tumours.     

Cytogenetic analysis of pancreatic carcinomas: intratumor heterogeneity and nonrandom pattern of chromosome aberrations

Twenty-nine nonendocrine pancreatic carcinomas (20 primary tumors and nine metastases) were studied by chromosome banding after short-term culture. Acquired clonal aberrations were found in 25 tumors and a detailed analysis of these revealed extensive cytogenetic intratumor heterogeneity. Apart from six carcinomas with one clone only, 19 tumors displayed from two to 58 clones, bringing the total number of clones to 230. Karyotypically related clones, signifying evolutionary variation, were found in 16 tumors, whereas unrelated clones were present in nine, the latter finding probably reflecting a distinct pathogenetic mechanism. The cytogenetic profile of pancreatic carcinoma was characterized by multiple numerical and structural changes. In total, more than 500 abnormal chromosomes, including rings, markers, homogeneously stained regions, and double minutes, altogether displaying 608 breakpoints, were detected. This complexity and heterogeneity notwithstanding, a nonrandom karyotypic pattern can be discerned in pancreatic cancer. Chromosomes 1, 3, 6, 7, 8, 11, 12, 17, and 19 and bands 1q12, 1q21, 3q11, 6p21, 6q21, 7q11, 7q22, 7q32, 11q13, 13cen, 14cen, 17q11, 17q21, and 19q13 were most frequently involved in structural rearrangements. A total of 19 recurrent unbalanced structural changes were identified, 11 of which were not reported previously: del(1)(q11), del(3)(p11), i(3)(q10), del(4)(q25), del(11)(p13), dup(11)(q13q23), i(12)(p10), der(13;15)(q10;q10), del(18)(q12), del(18)(q21), and i(19)(q10). The main karyotypic imbalances were entire-copy losses of chromosomes 18, Y, and 21, gains of chromosomes 7, 2, and 20, partial or whole-arm losses of 1p, 3p, 6q, 8p, 9p, 15q, 17p, 18q, 19p, and 20p, and partial or whole-arm gains of 1q, 3q, 5p, 6p, 7q, 8q, 11q, 12p, 17q, 19q, and 20q. In general, the karyotypic pattern of pancreatic carcinoma fits the multistep carcinogenesis concept. The observed cytogenetic heterogeneity appears to reflect a multitude of interchangeable but oncogenetically equivalent events, and the nonrandomness of the chromosomal alterations underscores the preferential pathways involved in tumor initiation and progression.     

Cytogenetic studies of epithelial ovarian carcinoma

We performed cytogenetic studies of 36 human epithelial ovarian carcinomas using in situ culture and robotic harvest. We obtained analyzable metaphases of all 36 tumors (100%). One or more chromosomally abnormal clones were observed in 80% of tumors. Common clonal chromosome gains (each occurring in six or more cases) included +1, +2, +3, +6, +7, +9, and +12. Common clonal chromosome losses (occurring in 12 or more cases) included -X, -4, -8, -11, -13, -15, -17, and -22. Common clonal structural abnormalities (occurring in four or more cases) involved regions 1p36, 1q32, 1q42, 3p13-->p26, 3q26-->q29, 7p22, 9q34, 11p13-p15, 17q21-->q23, 19p13.3, and 19q13.3. Trisomy 12 was noted as the sole anomaly in three of five borderline and grade 1 tumors. Two grade 2 tumors contained i(1q), -14, -15 and -22. The results suggest that the pathogenesis of borderline and low-grade tumors may differ from that of higher grade tumors. Two high-grade tumors had an apparent translocation between 17q21 and 19p13.3, two chromosome regions believed to be critical to ovarian carcinogenesis.     

Investigation of the dynamics underlying periodic complexes in the EEG

Cytogenetic analyses of 85 testicular germ cell tumors, of which 54 were karyotypically abnormal, showed recurrent breakpoints at chromosome bands 1p36, 1p13-1qh, 11q23, 19q13, and the pericentromeric regions of the acrocentric chromosomes. Postchemotherapy tumors had significantly more rearrangements of bands 3p25-p26, 6q16-q21, 8p22-p23 when compared with untreated tumors, while untreated tumors had more rearrangements of 9p22-p24 when compared with postchemotherapy tumors. Frequent breakpoints also were identified at 15q15 and 9qh in untreated tumors. Tumors of different histopathology, clinical stage, and treatment status showed no significant differences in the frequencies of i(12p)-positive and i(12p)-negative tumors.     

Hematologic malignancies with t(4;11)(q21;q23)--a cytogenetic, morphologic, immunophenotypic and clinical study of 183 cases. European 11q23 Workshop participants

A total of 183 hematologic malignancies with t(4;11)(q21;q23), including five variant translocations, were collected by the Workshop. Clinical, morphologic and immunophenotypic features were compiled, and karyotypes with variant t(4;11) or secondary chromosomal aberrations were reviewed. All cases were acute leukemias (AL): 173 acute lymphoblastic leukemias (ALL), six acute myeloid leukemias (AML), three unclassifiable AL, and one biphenotypic AL. Ten patients had treatment-associated AL. Females were overrepresented (104 vs 79) and the age distribution was clearly nonrandom; 34% of the cases occurred in infants below the age of 12 months. The remaining AL were evenly distributed among the other age groups, with the oldest patient being 79 years old. An increased white blood cell count (WBC) was reported in more than 90% of the cases, with hyperleukocytosis (> or =100 x 10(9)/l) in 64%. Additional chromosomal changes were detected in 55 (30%) cases, most often gain of the X chromosome, i(7)(q10), and trisomy 8, with frequent breakpoints in 1p36, 1q21, 7q10, 11p15, 12p13, 17p11, and 17p10. All recurrent secondary changes resulted in genomic imbalances, in particular gains of 1q, 7q, 8, and X and losses of 7p and 17p. Event-free and overall survival (EFS and OS) could be ascertained in 170 and 171 patients, respectively. Kaplan-Meier estimates of EFS and OS showed no differences with regard to gender, WBC, or presence of secondary chromosomal abnormalities, and there was no increase of EFS or OS among the 55 cases that had undergone bone marrow transplantation. However, age had an important prognostic impact, with significantly (P < 0.0001) longer EFS and OS in children 2-9 years old than among infants and younger children, patients aged between 10 and 39 years and older adults.     

Effect of regeneration and hyperplasia on levels of DNA base oxidation in rat liver

Clonal chromosome aberrations identified after short-term culture are presented for 13 chondrosarcomas; in 5 cases both the primary tumors and local recurrences were studied. The stemline chromosome number was hypodiploid or hyperhaploid in 9 tumors. The most frequent numerical anomalies were, in falling order of frequency, loss of chromosomes Y, 10, 13, and 6, and gain of chromosomes 7 and 20. No recurrent structural rearrangement was found, but chromosome bands 5q13, 1q21, 7p11, and 20q11 were each involved in three different rearrangements. Karyotypic heterogeneity was assessed in two different ways: as the presence of more than one clone in one sample and as the presence of different clones in different samples from the same surgical specimen. Clonal karyotypic evolution was demonstrated in 6 of the 7 cases in which two or more samples could be investigated. All 6 showed intersample heterogeneity. Intrasample heterogeneity was found in only 5 of the 28 samples with aberrations. By comparing the incidences of the nonrandomly occurring aberrations in stemlines and sidelines in the heterogeneous tumors, it was possible to conclude that loss of chromosome 13 and rearrangement of band 5q13 were early events in the clonal evolution.     

Bronchial mucosal immunoreactivity of sensory neuropeptides in severe airway diseases

DNA copy number changes were investigated in 29 leiomyosarcomas by comparative genomic hybridization. The most frequent losses were detected in 10q (20 cases, 69%) and 13q (17 cases, 59%). The most frequent gains were detected in 17p (16 cases, 55%). The most frequent high-level amplifications were detected in 17p (7 cases, 24%) and 8q (6 cases, 21%). A total of 137 losses and 204 gains were detected. Small tumors (less than 5 cm in diameter) displayed fewer changes per sample (3 to 11; mean, 7) than the other tumors (4 to 22; mean, 13). There was an increase in the number of gains from small tumors (mean, 4) to very large tumors (>20 cm; mean, 10). However, the number of losses was similar in small, large, and very large tumors (mean, 4.5). Tumor size-related aberrations were observed. Gains in 16p were detected in all small tumors but were infrequent in large and very large tumors (27% and 11%, respectively). Similarly, gains and high-level amplifications in 17p were more common in small (80%) than in very large tumors (33%). Gains in 1q, 5p, 6q, and 8q were not seen in any of the small tumors but were detected in large and very large tumors. Gains in 6q and 8q occurred in 8 of 9 cases (89%) of very large tumors, 5 of them with a high-level amplification in 8q.     

Distinct patterns of chromosomal alterations in high- and low-grade head and neck squamous cell carcinomas

Comparative genomic hybridization was performed on 30 primary head and neck squamous cell carcinomas. Fractional or entire DNA loss of chromosome 3p was a basic finding that occurred in 29 cases (97%). Additional DNA underrepresentations were observed in more than 50% of the cases on chromosomes 1p, 4, 5q, 6q, 8p, 9p, 11q, 13q, 18q, and 21q. Deletions on chromosomes 3p, 13q, and 17p were confirmed by loss of heterozygosity analysis. Entire or partial DNA copy number increases were identified for chromosome 3q in 26 cases (87%) with high-level amplifications at 3q24 and 3q27-qter. Overrepresentations were found in decreasing order of frequency at 11q13 (70%), 8q (57%), 19q (50%), 19p (47%), and 17q (47%). The use of comparative genomic hybridization superkaryograms of the group of well-differentiated carcinomas (G1) indicated that the deletions on chromosomes 3p and 9p along with the overrepresentation of 3q are associated with early tumor development. Accordingly, the undifferentiated tumors (G3) were characterized by additional deletions on chromosomes 4q, 8p, 11q, 13q, 18q, and 21q and overrepresentations on 1pter, 11q13, 19, and 22q, suggesting that these changes are preferentially associated with tumor progression.     

Cytogenetic aberrations in Ewing sarcoma: are secondary changes associated with clinical outcome?

BACKGROUND: Ewing sarcoma is associated with a nonrandom pattern of primary and secondary chromosomal aberrations. Whereas the finding of rearrangements of chromosome 22, usually in the form of a balanced translocation t(11;22)(q24;q12), is important diagnostically, nothing is known about the potential prognostic impact of the secondary chromosomal aberrations. PROCEDURE: During a 1 3-year-period, short-term cultured tumor samples from 21 children and young adults with Ewing sarcoma were cytogenetically analyzed successfully. RESULTS: Clonal chromosome aberrations were detected in 18 patients, 17 of whom had the characteristic t(11;22)(q24;q12) or variants thereof. The most frequent secondary change was +8, followed by +12, +2, +5, +9, +15, and gain of material from the long and short arms of chromosome 1. The only recurrent secondary change that was restricted to tumors from the ten patients that were dead at latest follow-up was gain of 1q material. Furthermore, all three patients with tumors with chromosome numbers over 50 had died, and the only patient with a tumor karyotype lacking chromosome 22 rearrangement was alive without evidence of disease. CONCLUSIONS: These data and previously published results indicate that the karyotypic pattern not only may be of diagnostic significance but also may be important prognostically.     

Molecular analysis of childhood primitive neuroectodermal tumors defines markers associated with poor outcome

PURPOSE: The diagnostic and prognostic significance of well-defined molecular markers was investigated in childhood primitive neuroectodermal tumors (PNET). MATERIALS AND METHODS: Using microsatellite analysis, Southern blot analysis, and fluorescence in situ hybridization (FISH), 30 primary tumors and six CSF metastasis specimens were analyzed for loss of heterozygosity (LOH) of chromosomes 1q31, 6q, 9q22, 10q, 11, 16q22, and 17p13.1 and/or high-level amplification of the c-myc gene. Experimental data were compared with clinical stage and outcome. RESULTS: LOH of chromosome 17p13.1 was found most frequently (14 of 30 tumors, six of six CSF metastasis specimens); LOH of chromosomes 10q, 16q22, 11, 6, 9q22, and 1q31 was observed in 20.6%, 20%, 14.3%, 12%, 10%, and 0%, respectively. Eight of 32 tumors and CSF specimens showed amplification of c-myc. All tumors with amplification of c-myc were resistant to therapy and had a fatal outcome (mean survival time, 9.3 months). Tumors that displayed LOH of chromosome 17p were associated with metastatic disease. The prognosis of these tumors was worse only when associated with amplification of c-myc. Three of three patients with LOH of 9q22 relapsed. CONCLUSION: In our study, amplification of c-myc was a poor-prognosis marker in PNET. LOH of chromosome 17p was associated with metastatic disease. Molecular analysis of primary tumors using these markers may be useful for stratification of children with PNET in future prospective studies. The other aberrations investigated were not of significant prognostic value, but may provide an entry point for future large-scale molecular studies.     

Karyotypic changes in phyllodes tumors of the breast

Cytogenetic analysis of short-term cultures of five phyllodes tumors of the breast-classified as benign (one tumor), borderline malignant (two tumors removed from the same breast in 1991 and 1993), and malignant (two tumors)--revealed clonal changes with simple structural abnormalities in the benign tumor, the borderline malignant tumors, and one malignant tumor in which benign areas and areas of borderline malignancy were also present. In contrast, the malignant tumor without admixed borderline malignant or benign areas had a complex karyotype. The karyotype of the benign phyllodes tumor was 46,XX,del(12)(p11p12)/46,XX,t(8;18)(p11;p11)/46,XX. The first borderline malignant phyllodes tumor had t(3;20)(p21;q13) as the sole abnormality. When the tumor recurred, this was no longer the only clone detected and the tumor karyotype was now 46,XX,t(3;20)(p21;q13)/46,XX,t(9;10)(p22;q22)/46,XX,t(1;8) (p34;q24)/46,XX,del(11)(q22-23)/46,XX. The malignant/borderline malignant/benign tumor had t(1;6)(p34;p22) as the sole clonal abnormality. Finally, the karyotype of the malignant phyllodes tumor which contained no benign or borderline malignant areas was 42,XX,der(1)t(1;4)(q21;q21),der(3)t(3;17)(q29;q21), -4,i(8)(q10), -10, -13,i(13)(q10),der(14)t(1;14)(q21;p11),der(14)t(4;14) (p12;p11), -17/80-90,idemx2, +del(1)(q12), +i(1)(p10), +dic(5;5)(p14;p14), +i(6)(p10), +del(7)(p11), +dup(7)(q11q36), +i(15)(q10),inc/46,XX. The findings indicate some cytogenetic similarities between benign/borderline malignant phyllodes tumors and fibroadenomas of the breast, presumably reflecting similar pathogenetic mechanisms in the two types of mixed-lineage tumors.     

The pericentromeric inversion, inv (6)(p25q13), is a novel diagnostic marker in chondromyxoid fibroma

Chondromyxoid fibroma is a benign bone tumor that arises most commonly in the metaphysis of long bones in young adults. The cytogenetic features of this tumor are not well known. In this study, four chondromyxoid fibromas were karyotyped after short-term cell culture. All of the tumors contained clonal rearrangements of chromosome 6, and each of these rearrangements involved band 6q13. Two tumors contained a pericentromeric inversion, inv (6)(p25q13), which was described recently in chondromyxoid fibroma. 6q13 rearrangements are not associated with other types of bone and soft tissue tumors, and the inv (6)(p25q13) is reported only in chondromyxoid fibroma. Hence, this cytogenetic marker might be helpful in distinguishing chondromyxoid fibroma from chondrosarcoma and other histologic mimics. The consistent occurrence of 6q13 rearrangements suggests a specific oncogenic mechanism in chondromyxoid fibroma, most likely involving oncogene activation.     

Monitoring of proteinuria in phase I studies in healthy male subjects

An extended analysis for loss of heterozygosity (LOH) on eight chromosomes was conducted in a series of 82 Wilms tumors. Observed rates of allele loss were: 9.5% (1p), 5% (4q), 6% (6p), 3% (7p), 9.8% (11q), 28% (11p15), 13.4% (16q), 8.8% (18p), and 13.8% (22q). Known regions of frequent allele loss on chromosome arms 1p, 11p15, and 16q were analyzed with a series of markers, but their size could not be narrowed down to smaller intervals, making any positional cloning effort difficult. In contrast to most previous studies, several tumors exhibited allele loss for multiple chromosomes, suggesting an important role for genome instability in a subset of tumors. Comparison with clinical data revealed a possible prognostic significance, especially for LOH on chromosome arms 11q and 22q with high frequencies of anaplastic tumors, tumor recurrence, and fatal outcome. Similarly, LOH 16q was associated with anaplastic and recurrent tumors. These markers may be helpful in the future for selecting high-risk tumors for modified therapeutic regimens.     

Genetic alteration mapping on chromosome 7 in primary breast cancer

Alterations of chromosome 7 are among the most frequent cytogenetic abnormalities found in human breast carcinoma. We examined genetic changes on chromosome 7 in 113 primary human breast tumors, using both microsatellite and restriction fragment length polymorphism/variable number of tandem repeats polymorphism markers mapping to the long arm (15 markers) and the short arm (8 markers). Allelic imbalance at 1 or more loci was observed in 50 (44%) of 113 tumors on the long arm of chromosome 7 and in 41 (36%) tumors on the short arm. Genetic changes of one arm were significantly associated with alterations of the other arm. The 50 7q-altered tumor DNAs exclusively showed a loss of heterozygosity (LOH), 23 (46%) at all informative loci tested on 7q and 27 (54%) at some loci (interstitial and/or telomeric deletions on 7q). The pattern of LOH of these 27 tumors enabled us to identify 3 distinct consensus regions of deletions on 7q, only 1 of which (7q31 region) has already been described in breast cancer. Among the 41 7p-altered tumor DNAs, 32 had a gain and/or loss of the entire short arm of chromosome 7. Fourteen tumor DNAs showed an allelic gain, and 18 tumor DNAs showed a LOH at each locus on the short arm. The other 9 7p-altered tumors showing partial random alterations of chromosome 7p revealed no common altered regions. This is the first report of an association between alterations of DNA sequences on chromosome 7p and breast cancer. The results suggest that tumor suppressor genes are present on the long arm of chromosome 7 and are associated with breast tumorigenesis. Moreover, the frequent loss or gain of a whole copy of chromosome 7p suggests the involvement of a gene dosage effect of this chromosomal arm in the pathogenesis of breast cancer.     

Fluorescence in situ hybridization analyses of hematologic malignancies reveal frequent cytogenetically unrecognized 12p rearrangements

Thirty-two hematologic malignancies--nine with cytogenetically identified 12p abnormalities and 23 with whole or partial losses of chromosome 12--were selected for fluorescence in situ hybridization (FISH) investigations of 12p. These analyses revealed structural 12p changes, such as translocations, deletions, insertions, inversions and amplification, in 20 cases. ETV6 rearrangements were detected in three acute leukemias. One acute undifferentiated leukemia had t(4;12)(q12;p13) as the sole anomaly. The second case, an acute myeloid leukemia (AML), displayed complex abnormalities involving, among others, chromosomes 9 and 12. The third case, also an AML, had an insertion of the distal part of ETV6 into chromosome arm 11q and into multiple ring chromosomes, which also contained chromosome 11 material, resulting in an amplification of a possible fusion gene. The fusion partners in these cases remain to be identified. Thirty-one additional breakpoints on 12p could be characterized in detail. The majority of these breaks were shown to result in interchromosomal rearrangements, possibly indicating the location of hitherto unrecognized genes of importance in the pathogenesis of hematologic malignancies. The FISH analyses disclosed terminal or interstitial 12p deletions in 18 cases. Seven myeloid malignancies showed deletions restricted to a region, including ETV6 and CDKN1B, which has been reported to be frequently lost in leukemias. In four cases, the deletions involved both these genes, whereas two AML displayed loss of CDKN1B but not ETV6, supporting previously reported findings indicating a region of deletion not including this gene. However, one myelodysplastic syndrome lacked one copy of ETV6 but not CDKN1B. Hence, we suggest a minimal region of deletion on 12p located between the ETV6 and CDKN1B genes.     

Cytogenetic and fluorescence in situ hybridization characterization of chromosome 1 rearrangements in head and neck carcinomas delineate a target region for deletions within 1p11-1p13

Cytogenetic analyses have revealed structural rearrangements of chromosome 1 in a large fraction of head and neck carcinomas (HNCA). These aberrations frequently affect chromosomal band 1p13 and the centromeric region, the latter often in the form of isochromosome i(1q) and whole-arm translocations. To delineate the critical region involved in rearrangements of proximal 1p, we have undertaken a more precise breakpoint mapping in 13 HNCAs, using metaphase fluorescence in situ hybridization with 11 yeast artificial chromosome (YAC) clones spanning 1p. All of the tumors had chromosome 1 changes at G-banding analyses. Fluorescence in situ hybridization showed that in almost all of the cases, at least one copy of chromosome 1 was affected by centromeric rearrangement. By the use of YAC clones mapped to juxtacentromeric regions and a centromere-specific alpha-satellite probe, we detected variable breakpoints in the whole-arm translocations. At the cytogenetic level, 1p13 rearrangements were frequent. However, molecular breakpoints within this band varied among the HNCAs tested. The lack of consistently rearranged chromosome segments indicates that the pathogenetically important consequence of 1p rearrangements in HNCAs is loss and/or gain of genes outside the breakpoint regions. In an assessment of the genomic imbalances, partial or complete overrepresentation of 1q was seen in eight cases. Loss of 1p material was also identified in eight cases; and in four of them, the deleted segments were too small to be discovered by G-banding analysis. The minimal overlapping deleted region was in the interval between YAC 959C4 (band p11-p12) and the centromere (p10). Our findings indicate that a target region potentially harboring tumor suppressor gene(s) crucial for HNCA is located within chromosomal bands 1p11-p13.     

Multicolor spectral karyotyping identifies new recurring breakpoints and translocations in multiple myeloma

Karyotypic information on multiple myeloma (MM) is less extensive than that on other myeloid or lymphoid malignancies due to low mitotic activity of plasma cells. An add(14)(q32) marker chromosome has been reported to be the most frequent recurring abnormality in clonally abnormal cases; in approximately one third of the latter cases, this marker has been identified as a der(14)t(11;14)(q13;q32) chromosome. To map chromosomal breakpoints, characterize the add(14)(q32) marker chromosomes, and to identify other recurring translocations in MM, we used spectral karyotyping (SKY) to analyze a panel of nine bone marrow (BM) biopsy samples from eight patients and 10 tumor cell lines derived from MM patients. SKY involves hybridization of 24 fluorescently labeled chromosome painting probes to metaphase spreads in such a manner that simultaneous visualization of each of the chromosomes in a different color is accomplished. By this method, it was possible to define all chromosomal rearrangements and identify all of the clonal marker chromosomes in tumor cells. By detailed mapping of breakpoints of rearrangement, it was also possible to identify several novel recurring sites of breakage that map to the chromosomal bands 3q27, 17q24-25, and 20q11. The partner chromosomes in translocations that generated the add (14)(q32) marker chromosomes were identified in all cases in which they were detected by G-banding (one biopsy and six cell lines). In addition, two new translocations involving band 14q32, ie, t(12;14)(q24;q32) and t(14;20)(q32;q11) have also been identified. These studies demonstrate the power of SKY in resolving the full spectrum of chromosome abnormalities in tumors.     

Hearing aid effect in older females

We report the use of dual-colour chromosome painting to determine the exact nature of certain chromosome rearrangements observed in the pig (Sus scrofa domestica). The chromosomal abnormalities were detected by GTG- and RBG-banding techniques. The initially proposed interpretations were: (1) rcp(6;13)(p1.5;q4.1); (2) rcp(11;16)(p1.4;q1.4); (3) rcp(6;16)(p1.1;q1.1); (4) rcp(13;17)(q4.1;q1.1); (5) rcp(6;14)(q2.7;q2.1); (6) rcp(3;5)(p1.3;q2.3); (7) rcp(2; 14)(q1.3;q2.7); (8) rcp(15;17)(q1.3;q2.1). Hybridizations were carried out with biotin- and digoxigenin-labelled probes obtained by priming authorizing random mismatches polymerase chain reaction (PARM-PCR) amplification of porcine flow-sorted chromosomes. In some cases, i.e. (1), (4), (5), (6), (7) and (8), the fluorescence in situ hybridization (FISH) results allowed confirmation of the interpretations proposed with classical cytogenetic methods. Chromosome painting proved the reciprocity of the translocation in cases (1), (6) and (8), whereas modifications of the formula were proposed for case (2). Primed in situ DNA labelling (PRINS) experiments have also been carried out in case (3) using a primer specific for the centromeres of acrocentric chromosomes (first experiment) or a primer specific for the centromeres of a subset of meta- and submetacentric chromosomes including chromosome 6 (second experiment). It allowed us to demonstrate that the breakpoints occurred in the centromeric region of chromosome 16 and in the p. arm of chromosome 6, just above the centromere.     

Mapping of chromosomal imbalances in pancreatic carcinoma by comparative genomic hybridization

To identify recurrent chromosomal imbalances in pancreatic adenocarcinoma, 27 tumors were analyzed by using comparative genomic hybridization. In 23 cases chromosomal imbalances were found. Gains of chromosomal material were much more frequent than losses. The most common overrepresentations were observed on chromosomes 16p (eight cases), 20q (seven cases), 22q (six cases), and 17q (five cases) and under-representations on a subregion of chromosome 9p (eight cases). Distinct high-level amplifications were found on 1p32-p34, 6q24, 7q22, 12p13, and 22q. These data provide evidence for a number of new cytogenetically defined recurrent aberrations which are characteristic of pancreatic carcinoma. The overrepresented or underrepresented chromosomal regions represent candidate regions for potential oncogenes and tumor suppressor genes, respectively, possibly involved in pancreatic tumorigenesis.