Search for chromosome instability in lymphocytes with germ-line mutations in DNA mismatch repair genes.

All colorectal cancer results from the accumulation of critical genetic alterations; however, the mechanisms of acquiring these mutations appear to be different in hereditary nonpolyposis colon cancer (HNPCC) and sporadic tumors with microsatellite instability compared with sporadic tumors with no microsatellite instability. To further explore the possible mechanisms of cancer predisposition in HNPCC, we studied chromosome breakage and induction of aneuploidy in the lymphoblastoid cell lines of four patients who were heterozygous for mutations in either hMSH2 or hMLH1--two components of the DNA mismatch repair complex. Cells were cultured under different stress systems, including exposure to bleomycin, mitomycin C, bromodeoxyuridine-induced sister chromatid exchange, and a DNA alkylator, N-methyl-N'-nitro-N-nitrosoguanidine. No significant differences were detected in the levels of major or minor chromosome breakage or aneuploidy compared with controls. These results suggest that a single "hit" to a DNA mismatch repair gene does not confer appreciable susceptibility to structural or numerical chromosomal alterations, which is consistent with previous observations that HNPCC-related cancers are more likely to be near diploid than are sporadic colon cancers.

Cytogenetic analysis of aggressive meningiomas: possible diagnostic and prognostic implications.

BACKGROUND: Published karyotypes from aggressive (atypical and malignant) meningiomas are few, but suggest clonal evolution from benign tumors with monosomy 22 to aggressive forms with additional abnormalities. The goal of this study was to identify the most frequent karyotypic abnormalities associated with aggressive histopathology and biologic behavior. METHODS: Eight intracranial meningiomas exhibiting histologically atypical features at the time of intraoperative diagnosis were chosen for cytogenetic analysis. The study set was comprised entirely of histologically atypical meningiomas. Four were considered malignant; three on the basis of brain invasion and one due to extracranial metastases. None was histologically anaplastic. RESULTS: Chromosomal abnormalities were demonstrated in 6 cases (75%), 5 of which were complex (63%). Loss of chromosome 22 was identified in two cases, both of which were associated with additional aberrations. Abnormalities most frequently involved chromosomes 1 (63%), 3 (50%), and 6 (63%). Four cases (50%) had dicentric or ring chromosomes. An additional 47 previously reported karyotypes from atypical and malignant meningiomas were reviewed. Comparison with published karyotypes of 200 histologically benign meningiomas served to underscore the increased frequency of complex karyotypes, chromosome 1, 3, and 6 abnormalities, and telomeric associations in the aggressive tumors. Apparently normal karyotypes as well as monosomy 22 alone were more frequently associated with benign, nonatypical histopathology. CONCLUSIONS: These findings suggest a possible role for cytogenetic analysis in determining the prognosis and perhaps in refining the diagnosis of atypical or aggressive meningiomas. Further studies are necessary to determine the significance of complex karyotypes, chromosome 1, 3, and 6 abnormalities, and telomeric associations, particularly whether they portend a more aggressive clinical course in meningiomas lacking features of histologic atypia.

Cytogenetic studies of four hemangiopericytomas.

We report cytogenetic studies on four hemangiopericytomas using in situ culture and robotic harvesting. Simple clonal chromosome abnormalities were observed in each of the three successful tumors. A cerebral tumor had a nonconstitutional 46,XX,t(7;12)(p15;q15) karyotype. A recurrent cerebral tumor had two cell lines: one with a 46,XY,t(2;12)(p13;q24.1) karyotype and one with a 46,XY,t(5;7)(q13;p15) karyotype. Each of the metaphases from a lung tumor had a 46,Y,inv(X)(p22.3q13) karyotype. We conclude that simple nonconstitutional balanced chromosome anomalies of 7p15 and 12q are common in cerebral hemangiopericytomas. It is possible that balanced anomalies of these chromosome regions are related to the pathogenesis of this tumor type.

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.

Gliosis specimens contain clonal cytogenetic abnormalities.

The relevance of sex chromosome aneusomy and trisomy 7 in neoplastic brain tissue is controversial. For better understanding of the relative importance of these anomalies, we made a conventional cytogenetic study of cells from tissue obtained from patients who underwent partial cerebral resection for a seizure disorder. Each specimen exhibited "gliosis," but none contained histologically identifiable tumor cells. Sixty-six specimens were analyzed by routine cytogenetic methods. Nonclonal abnormalities were observed in 11.6% of the cells (86% of cases) analyzed. In 11 cases, however, simple clonal karyotypes were observed. Of these cases, six involved loss of a Y chromosome and three involved loss of an X chromosome. Among the cases with loss of an X chromosome, two exhibited multiple abnormal clones. One of these cases had trisomy 7 as well as trisomy 18, and another had a supernumerary psu dic(15)(q13). The supernumerary chromosome was constitutional. One patient had possible Klinefelter syndrome. An additional case had a clonal del(10)(q23) that may have resulted from a hereditary fragile site. We conclude that although some of the apparently acquired clonal and nonclonal abnormalities may be due to a consistent in vitro artifact, it is probable that they are present in the brain tissue itself. Whatever the cause, caution should be used in interpretating cytogenetic abnormalities observed in brain tumor specimens.

Cytogenetic and loss of heterozygosity studies in ependymomas, pilocytic astrocytomas, and oligodendrogliomas.

Cytogenetic and/or loss of heterozygosity studies were performed on 13 ependymomas, 11 pilocytic astrocytomas, and 18 oligodendrogliomas. Loss of chromosome 22 was the most frequent genetic abnormality among the ependymomas. We found no consistent genetic abnormality in pilocytic astrocytomas. The most common genetic abnormality in oligodendrogliomas was loss of a portion of chromosome 19. Each informative oligodendroglioma had loss of alleles mapped to the long arm (q) of chromosome 19. One oligodendroglioma had an apparent homozygous deletion of the D19S8 locus. Our results, when combined with those in the literature, indicate that chromosomes 9, 11, and 22 may harbor genes important for the pathogenesis of ependymomas and that 19q probably harbors a gene important for the pathogenesis of oligodendrogliomas.

Correlation of cytogenetic analysis and loss of heterozygosity studies in human diffuse astrocytomas and mixed oligo-astrocytomas.

The aims of this study were to correlate cytogenetic studies and molecular genetic loss of heterozygosity (LOH) analyses in human astrocytomas and mixed oligo-astrocytomas, and to locate putative tumor suppressor genes on chromosome 10. Paired blood and tumor samples from 53 patients were analyzed. The tumors included 45 diffuse astrocytomas (39 grade 4, 4 grade 3, and 2 grade 2), 1 astroblastoma, and 7 mixed oligo-astrocytomas (2 grade 4, 4 grade 3, and 1 grade 2). By cytogenetic analyses the most common numeric chromosome abnormalities were +7, -10, -13, -14, -17, +19, -22, and -Y. The most common structural abnormalities involved chromosome arms 1p, 1q, 5p, and 9p. By LOH and dosage analysis the most common molecular genetic abnormalities were of chromosome arms 5p, 6p, 7q, 9p, 10p, 10q, 13q, 14q, 17p, and 19p. When the results of all methods were combined, the most commonly abnormal chromosomes were, in descending frequency, 10, Y, 17, 7, 13, and 9. In 80 percent of cases the cytogenetic and molecular genetic studies were concordant. LOH studies were more sensitive in detecting loss of genetic material than cytogenetic analyses and accounted for 60% of the discordant results. When there were structural abnormalities, such as translocations or inversions, cytogenetic analysis was more sensitive in detecting an abnormality than molecular genetic studies. In addition to the 24 tumors which appeared to lose an entire copy of chromosome 10, there were 10 tumors with molecular genetic or cytogenetic evidence of loss of only a portion of chromosome 10. The genetic analyses of these tumors suggest that there are 2 regions on chromosome 10 that may contain potential tumor suppressor genes. One lies distal to locus D10S22 from 10q22 to 10qter, and the other lies proximal to locus TST1 on the 10q arm near the centromere or on the 10p arm.

Cytogenetic and molecular genetic studies of follicular and papillary thyroid cancers.

Cytogenetic studies have shown frequent clonal abnormalities in papillary carcinoma (PTC) and follicular carcinoma (FTC). Loss of heterozygosity (LOH) may suggest the presence of tumor suppressor genes and has not been reported in these neoplasms. These studies were undertaken to determine if consistent chromosomal abnormalities are associated with thyroid cancer, to determine likely regions for molecular genetic investigations, and to determine if there is allelic loss in thyroid tumors. Cytogenetic analysis of 26 PTC and 5 FTC showed clonal abnormalities in 9 and included -Y, +5, or inv(10)(q11.2q21.2) in PTC, and -Y or near haploidy in FTC. Using DNA probes specific for chromosomes 1, 3, 10, 16, and 17, we carried out restriction fragment length polymorphism analysis on 6 FTC, 3 follicular adenomas (FA), and 12 PTC. LOH of all informative loci on chromosome 3p was observed in all 6 FTC, but not in FA or PTC. No LOH was observed for loci mapped to chromosome 10 in PTC. Our results suggest: cytogenetic abnormalities of chromosome 10q are associated with PTC; cytogenetic and molecular abnormalities of chromosome 3 are associated with FTC; and a tumor suppressor gene may be present on the short arm of chromosome 3 important for the development or progression of FTC.

Cytogenetics of six follicular thyroid adenomas including a case report of an oxyphil variant with t(8;14)(q13;q24.1).

Cytogenetic analyses were performed on six follicular thyroid adenomas. Five had normal karyotypes and one, an oxyphil adenoma, had a t(8;14)(q13;q24.1). This patient also had a history of pleomorphic adenoma of the parotid gland. This clonal abnormality may suggest a primary genetic lesion in this patient who had two different benign neoplasms.

Cytogenetic analyses on giant-cell tumors of bone.

Giant-cell bone tumors are considered to be benign proliferations composed of poorly differentiated mononuclear cells and large multinucleated giant cells with the appearance of osteoclasts. Treatment is usually surgical resection, but there is a small risk of local recurrence and metastasis. Cytogenetic analyses were performed on giant-cell bone tumors of six consecutive patients. Chromosomally abnormal clones were found in three of the tumors, but no two patients had the same chromosome abnormality. Thus, there was no correlation between any specific chromosome change and the clinical behavior or histology of giant-cell bone tumors. However, all of the tumors had a significantly higher incidence of nonclonal chromosome abnormalities than is encountered in cultures of normal cells. The most common nonclonal abnormalities involved unusual telomere-to-telomere chromosome translocations. These findings suggest that the cells in these tumors are chromosomally unstable. The telomeres most frequently involved were on the long arm of chromosomes 19 and 20.

Cytogenetic studies in 11 patients with small cell carcinoma of the lung.

Small cell carcinoma of the lung has reportedly been associated with structural abnormalities of the short arm of chromosome 3, but most of the previous studies were done on long-term cultures that involved cell lines. In the current study, we investigated the chromosome abnormalities in specimens from primary lung tumors grown in short-term cultures. Cytogenetic studies were done in 11 patients with small cell carcinoma of the lung, and a chromosomally abnormal clone was observed in each tumor. An abnormality of chromosome 3 was observed in six of these tumors.

Recognition by the human immune system of candidate vaccine epitopes of Toxoplasma gondii measured by a competitive ELISA.

A competitive ELISA for the detection of human antibody to specific candidate vaccine epitopes of Toxoplasma gondii is described. The method is based on competition between antibody in human serum and murine monoclonal antibody to bind to a crude sonicated antigen of T. gondii. A total of 301 normal human sera were tested against a panel of four anti-T. gondii murine monoclonal antibodies. The results obtained with two of the monoclonal antibodies (FMC 22 and FMC 23) gave good agreement with those of an indirect ELISA for human IgG to T. gondii, a measure of previous exposure to the parasite. The epitopes against which these two monoclonal antibodies are directed were recognized by the immune system of all patients previously exposed to the parasite, while greater than 92 and greater than 96% respectively of these patients recognized the epitopes which the other two monoclonal antibodies (FMC 18 and FMC 19) are directed against. An ELISA double antibody binding system was used to ascertain relationships in the epitope binding sites of the four monoclonal antibodies. The data obtained demonstrated that FMC 19 and FMC 22 bound to related epitopes. FMC 18, FMC 22 and FMC 23 also bound to related epitopes, but the binding of FMC 19 was found to be independent of the binding of FMC 18 and FMC 23 to their epitope binding sites.

Chromosomally abnormal clones and nonrandom telomeric translocations in cardiac myxomas.

Cardiac myxomas from eight patients were examined cytogenetically in short-term cultures. Cultures could not be established in two of the eight cases. Chromosomally abnormal clones occurred in two of the myxomas; their karyotypes were 45,X,-Y,+7,-18 and 45,X,-Y. In three other myxomas, we found a rare kind of telomere-to-telomere translocation between chromosomes. The telomeres predominantly involved in these three tumors were the 2qter (the end of the long arm of chromosome 2), the 12pter (the end of the short arm of chromosome 12), and Yqter (the end of the long arm of the Y chromosome), respectively. In one other myxoma, 20% of the cells were tetraploid. These findings support the concept that myxomas are neoplastic; those with an abnormal clone may even have malignant potential. The unusual telomere-to-telomere translocations were not observed in a clonal pattern. They may represent a specific type of chromosomal instability associated with a defect in repair or replication of telomeric DNA.

Chromosome abnormalities in malignant hematologic disorders.

Certain chromosome abnormalities have been detected in routine cytogenetic studies of patients with hematologic disorders. This article is a cytogenetic and clinical review of 28 structural and 15 numeric chromosome abnormalities. As a group, the structural abnormalities involved 40 different chromosome breakpoints and included 13 types of translocations, 8 deletions, 3 isochromosomes, 3 inversions, and 1 duplication. The numeric abnormalities included 4 types of monosomy, 10 trisomies, and a near-haploid category. We determined the relative frequency for each of these anomalies in our practice by reviewing the results of 1,228 consecutive specimens studied between 1979 and 1984 in which a chromosomally abnormal clone was found; 61% of these specimens had one or more of the selected anomalies. The three most common translocations were 9;22 translocations (378 specimens), 8;21 translocations (15 specimens), and unbalanced abnormalities derived from 1;7 translocations (13 specimens). The two most common deletions were those involving the long arm of chromosomes 5 (101 specimens) and 20 (65 specimens). The most common isochromosome was i(17q) (33 specimens). The two most common types of monosomy were loss of a Y chromosome (118 specimens) and monosomy 7 (97 specimens). The three most common trisomies were + 8 (161 specimens), +21 (53 specimens), and +19 (31 specimens). Each of the 43 anomalies was observed in patients with different types of hematologic disorders, but in most cases one kind of neoplasm usually predominated.

Specificity of the enzyme-linked immunosorbent assay (ELISA) for Toxoplasma IgG antibody.

An ELISA developed for Toxoplasma IgG antibody was demonstrated to be more sensitive than the current reference tests, the indirect haemagglutination antibody test (IHAT) and the indirect immunofluorescence test (IIFT). No additional cross reactions were found in the ELISA with sera from patients with other parasitic infections, and there was no interference due to the presence of either rheumatoid factor or antinuclear antibodies.

A tdic(5;15)(p31;p11) chromosome showing variation for constriction in the centromeric regions in a patient with the cri du chat syndrome.

Some dicentric chromosomes show only one primary constriction at metaphase and behave in cell division as if they are monocentric. The few previous reports of tdic (translocation dicentric) chromosomes showing one morphologic indicate that among the cells of an individual the same centromere consistently shows the primary constriction. The present case deals with a tdic(5;15)(p13;p11) chromosome that is an exception to this pattern. Scoring 98 GTG-, C-, and QFQ-banded metaphases specifically for primary constrictions revealed 15 (15%) containing a tdic chromosome with a single primary constriction. Among these chromosomes, 8 (8%) were at the chromosome 15 centromere and 7 (7%) were at the chromosome 5 centromere. The remaining 83 (85%) tdic chromosomes showed two primary constrictions. We analyzed a total of 172 metaphases from peripheral blood, and all except 3 (1.7%) contained the tdic chromosome. Among these three cells, the tdic chromosome was broken in two and absent in one, which indicates that there was some unstable separation of this dicentric in cell division. In two metaphases, there was a chromatid gap at the site of one centromere. Possibly, the absence of certain primary constrictions was associated with deletion of centromeres. This mechanism may be a continual source for additional centromere inactivation during the life of this patient. This case demonstrates that for some dicentrics either centromere may become nonfunctional and inactivation can occur more than once within an individual. The karyotype of this patient was 45,XX,tdic(5;15)(p31;p11). Thus, she was monosomic for about 3/4 of the chromosome 5 short arm. Clinically, this infant had a shrill catlike cry and facies of the cri du chat syndrome.