PURPOSE: Fragile sites are points on chromosomes which tend to break non-randomly when exposed to specific chemical agents or conditions of tissue culture. The chromosomal break induced by the antineoplastic drug, 1-beta-D-arabinofuranosyl-cytosine(Ara-c), was investigated to study the laboratory conditions in which the incidence of chromosomal break could be enhanced. Besides, the fragile sites induced by Ara-C were investigated and compared to the already known locations of the specific chromosomal alterations observed in specific neoplasms. METHODS: T-lymphocytes from theree normal males and three females were cultured for 48 hours. Cells from each individual were exposed to the Ara-C for an additional 24 hours. After the caffeine was added during the last six hours culture, the metaphase chromosomes were prepared following the conventional method. A site was considered fragile if it was found to break two or more per 100 chromosomal breaks in more than four of six individuals tested. RESULTS: Ara-C induced 252.1 chromosomal breaks per 100 mitotic cells and this result was significantly higher than that of the control, which induced 25.2 breaks(P<0.05). The incidence of the chromosomal break by Ara-C was higher, if cultured in the MEM-FA, which has no folic acid, than in the RPMI 1640 which contains enough folic acid(P<0.05). The most common break site by Ara-C was 3p14.2(FRA3B). There were 20 fragile sites induced by Ara-C. Among these 20 fragile sites, seven coincided with the locations of the mapped oncogenes, JUN, SKI, REL, N-MYC, FHIT, MET, ETS-1, and FOS. CONCLUSIONS: S phase specific chemotherapeutic agent, Ara-C, induced the expression of the chromosomal fragile sites effectively using the T-lymphocyte in vitro. Some of the fragile sites by Ara-C highly coincided with the oncogenes and neoplasm specific chromosome breakpoints. In this regard, the fragile sites reported here could provide the unknown neoplasm related chromosomal alternation points.
Caffeine ; Chromosome Breakage* ; Chromosome Breakpoints ; Cytarabine ; Female ; Folic Acid ; Genes, jun ; Humans ; Incidence ; Male ; Metaphase ; Oncogenes ; S Phase ; T-Lymphocytes

Nickel is a carcinogen in nickel refinery workers. Few chromosome studies have been performed on nickel toxicity. Therefore, this study was performed to investigate cytogenetic toxicity of nickel in human cultured lymphocytes by chromosome aberration, and sister chromatid exchange (SCE) which is a sensitive indicator of carcinogen and mutagen. The results indicate that nickel chloride and nickel sulfate led to a increase in SCE frequencies very significantly, although absolute value of SCE was low. In chromosome aberration, chromosome gap was increased to increment of concentration while chromosome break was not.
Chromosome Aberrations* ; Chromosome Breakage ; Cytogenetics ; Humans ; Humans* ; Lymphocytes* ; Nickel* ; Siblings* ; Sister Chromatid Exchange*

BACKGROUND: Fanconi's anemia (FA) is an autosomal recessive disease characterized by aplastic anemia, pre-malignancy, congenital malformations and chromosome breakage syndromes. As up to 30% of patients have no detectable congenital anomalies, the modern diagnosis of FA rests on chromosomal breakage of patient's cells induced by chemical clastogens such as diepoxybutane (DEB) or mitomycin-C (MMC). METHODS: We have done chromosome breakage test to differentiate FA from 11 aplastic anemia, three Diamond-Blackfan syndrome, three myelodysplastic syndrome, one acute leukemia with congenital anomaly and three siblings of FA. The peripheral blood lymphocytes from each individual were co-cultured in phytohemagglutinin-containing medium by the three methods, i.e., DEB treated, MMC treated and un-treated. RESULTS: Five cases were found to have increased chromosomal breakages to DEB and MMC, confirming diagnosis of FA. Other 21 cases showed no increased chromosomal breakages. No overlap was found between FA group and others (P<0.01). In one FA, there was no increased spontaneous breakage, but increased breakage to DEB and MMC. Of five FA, one case showed no congenital anomalies. CONCLUSIONS: Chromosme breakage test was shown to be simple, reliable and useful in ascertaining the diagnosis of FA.
Anemia, Aplastic ; Chromosome Breakage* ; Diagnosis* ; Fanconi Anemia* ; Humans ; Leukemia ; Lymphocytes ; Mitomycin ; Mutagens ; Myelodysplastic Syndromes ; Siblings

BACKGROUND: Hypersensitivity to both cell-killing and chromosome-damaging effects of ionizing radiation is a consistent feature of cells from individuals with ataxia-telangiectasia (AT). This radiobiological behavior of AT cells is a component of genetic instability and may contribute to cancer risk. Also, heterozygotes for AT-mutated (ATM) genes have no clinical expressions of AT, but may become cancer prone with a moderate increase in in-vitro radiosensitivity. METHODS: We performed a chromosomal analysis on lymphocytes from 3 AT patients, 5 obligate AT carriers (siblings and parents of the patients), and 5 normal controls. RESULTS: Increases in chromosomal breakages after irradiation with 1 gray/min in cells from AT patients ranged from 0.65 to 0.83 rearrangements per metaphase, while in the carriers and controls the levels of breakage were between 0 and 0.15 per metaphase cells (P<0.05). CONCLUSIONS: These results are consistent with previously reported chromosomal radiosensitivity in AT patients. However, carriers do not show moderate radiosensitivity due to various technical factors such as the dose or distance of radiation. Although this research has some limitations due to the small numbers of patients, carriers and controls, this method may be an easy and useful diagnostic tool for AT patients in Korea. (J Korean Neurol Assoc 19(5):509~513, 2001)
Ataxia Telangiectasia* ; Ataxia* ; Chromosome Breakage ; Heterozygote ; Humans ; Hypersensitivity ; Korea ; Lymphocytes* ; Metaphase ; Parents ; Radiation Tolerance ; Radiation, Ionizing

OBJECTIVETo analyze the meiotic segregation results of male reciprocal chromosome translocation by fluorescence in situ hybridization (FISH).

METHODSMulti-color FISH using 3 combined probes located in any 3 chromosome segments on both sides of two breakpoints was performed on the de-condensed sperm head to analyze the sperm chromosomal contents and segregation patterns.

RESULTSFour male reciprocal translocation carriers were included in the study, with the karyotypes of 46, XY, t(2;18) (p16; q23); 46, XY, t(4;6) (q34;q21); 46, XY, t(8;13) (q23;q21) and 46, XY, t(4;5) (4q31;5q13), respectively. The results showed that 4 carriers had different proportions of various segregated spermatozoa. The spermatozoa of alternate, adjacent-1, adjacent-2, 3:1, non-disjunction in meiosis II, and 4:0 or diploidy accounted for 27.1%-49.4%, 26.9%-37.6%, 2.7%-15.7%, 8.6%-32.7%, 0.2%-1.9%, and 0.1%-0.4%, respectively.

CONCLUSIONFor each-reciprocal translocation carrier seems to have a particular meiotic segregation results, FISH analysis on sperm head should be done for each carrier in order to provide an accurate genetic counseling.

Chromosome Breakage ; Heterozygote ; Humans ; In Situ Hybridization, Fluorescence ; Karyotyping ; Male ; Meiosis ; genetics ; Spermatozoa ; metabolism ; Translocation, Genetic ; genetics

To investigate fragile sites induced by aphidicolin which is a specific inhibitor of eukaryotic DNA polymerase a which is primarily associated with chromosomal DNA replication in human lymphocytes, HaCat cells (human keratinocytes) and MRC-5 cells (human embryonic lung fibroblast), we cultured each cells in RPMI 1640 with 10% fetal calf serum and 2% PHA. Treatment of the cells with aphidicolin was generally carried out for the last 24 hours of culturing. The drug was dissolved in DMSO and used at final concentrations of 0.05~0.15 mg/ml, corresponding to a maximum DMSO concentration of 0.028%. Karyotypes of each cells were performed by routine method, and 50 metaphases were scored for each culture for analysis of breakage rate. Experimental cells treated with APC showed a dose dependent sensitivity and the amounts of chromosome breakage induced by APC are the highest in concentration of 0.15 mg/ml. The frequency of fragile sites on each cells appeared in MRC-5 cells, lymphocytes and HaCat cells in order. The common fragile sites on all experiments was 16q23, and the common fragile sites on embryonic cells was 1p31. It can be concluded that gene or nucleic acid which is located on 16q23 is the most important factor to induce chromosomal breakage with sensitivity to aphidicolin and 1p31 is important site to induce chromosomal breakage in embryonal cells.
Aphidicolin* ; Chromosome Breakage ; Dimethyl Sulfoxide ; DNA ; DNA Replication ; Humans ; Karyotype ; Lung ; Lymphocytes* ; Metaphase

Supernumerary B chromosomes were found in Lilium amabile (2n = 2x = 24), an endemic Korean lily that grows in the wild throughout the Korean Peninsula. The extra B chromosomes do not affect the host-plant morphology; therefore, whole transcriptome analysis was performed in 0B and 1B plants to identify differentially expressed genes. A total of 154,810 transcripts were obtained from over 10 Gbp data by de novo assembly. By mapping the raw reads to the de novo transcripts, we identified 7,852 differentially expressed genes (log₂FC > |10|), in which 4,059 and 3,794 were up-and down-regulated, respectively, in 1B plants compared to 0B plants. Functional enrichment analysis revealed that various differentially expressed genes were involved in cellular processes including the cell cycle, chromosome breakage and repair, and microtubule formation; all of which may be related to the occurrence and maintenance of B chromosomes. Our data provide insight into transcriptomic changes and evolution of plant B chromosomes and deliver an informative database for future study of B chromosome transcriptomes in the Korean lily.
Cell Cycle ; Chromosome Breakage ; Gene Expression Profiling ; Gene Expression ; Lilium ; Microtubules ; Plants ; Transcriptome

Objective: To analyze the clinical and molecular diagnostic status of Fanconi anemia (FA) in China. Methods: The General situation, clinical manifestations and chromosome breakage test and genetic test results of 107 pediatric FA cases registered in the Chinese Blood and Marrow Transplantation Registry Group (CBMTRG) and the Chinese Children Blood and Marrow Transplantation Registry Group (CCBMTRG) from August 2009 to January 2022 were analyzed retrospectively. Children with FANCA gene variants were divided into mild and severe groups based on the type of variant, and Wilcoxon-test was used to compare the phenotypic differences between groups. Results: Of the 176 registered FA patients, 69 (39.2%) cases were excluded due to lack of definitive genetic diagnosis results, and the remaining 107 children from 15 hospitals were included in the study, including 70 males and 37 females. The age at transplantation treatment were 6 (4, 9) years. The enrolled children were involved in 10 pathogenic genes, including 89 cases of FANCA gene, 7 cases of FANCG gene, 3 cases of FANCB gene, 2 cases of FANCE gene and 1 case each of FANCC, FANCD1, FANCD2, FANCF, FANCJ, and FANCN gene. Compound heterozygous or homozygous of loss-of-function variants account for 69.2% (72/104). Loss-of-function variants account for 79.2% (141/178) in FANCA gene variants, and 20.8% (37/178) were large exon deletions. Fifty-five children (51.4%) had chromosome breakage test records, with a positive rate of 81.8% (45/55). There were 172 congenital malformations in 80 children.Café-au-Lait spots (16.3%, 28/172), thumb deformities (16.3%,28/172), polydactyly (13.9%, 24/172), and short stature (12.2%, 21/172) were the most common congenital malformations in Chinese children with FA. No significant difference was found in the number of congenital malformations between children with severe (50 cases) and mild FANCA variants (26 cases) (Z=-1.33, P=0.185). Conclusions: FANCA gene is the main pathogenic gene in children with FA, where the detection of its exon deletion should be strengthened clinically. There were no phenotypic differences among children with different types of FANCA variants. Chromosome break test is helpful to determine the pathogenicity of variants, but its accuracy needs to be improved.
Male ; Female ; Humans ; Child ; Fanconi Anemia/genetics* ; Chromosome Breakage ; Retrospective Studies ; Exons ; China/epidemiology*

OBJECTIVE: The fragile histidine triad (FHIT) gene is located at chromosome 3p14.2 and encompasses the common fragile site, FRA3B, which may contribute to chromosome breakage and rearrangement of cancer cells. In this study, we examined whether transcriptional alterations of FHIT gene play a role in the development of human cervical carcinomas and the possibility that hypermethylation of CpG islands serves for FHIT inactivation. We then analyzed FHIT expression status with clinical parameters to determine whether it has any prognostic significance. METHODS: The study group included 50 squamous carcinomas, 4 adenocarcinomas, 4 adenosquamous carcinomas, 7 noncancerous tissue and the clinical stage is composed of 4 Ia, 37 Ib and 17 II. Tissue specimens were snap-frozen in liquid N2 and stored at -70degrees C until used. To examine for abnormal transcripts of the FHIT gene, quantitative RT-PCR, genomic DNA-PCR and nonisotopic RT-PCR-SSCP analysis were performed using the standard method. The methylation status was determined by methylation specific PCR. RESULTS: The FHIT gene was down-regulated in 15 of 58 (25.9%) cervical carcinomas. FHIT promoter hypermethylation was detected in 15 of 15 (100%) abnormally expression in cervical carcinomas. CONCLUSION: In this study, gene mutation is not a main mechanism for FHIT inactivation, but the aberrant promoter hypermethylation may be correlated with decreased expression of the FHIT gene. The significance of decreased expression of FHIT does not appear to be an independent prognostic factor in cervical cancers, although a still larger sample of patients will be required to asses this issue definitively.
Adenocarcinoma ; Carcinoma, Adenosquamous ; Carcinoma, Squamous Cell ; Chromosome Breakage ; CpG Islands ; Equidae ; Histidine* ; Humans ; Methylation ; Polymerase Chain Reaction ; Uterine Cervical Neoplasms

OBJECTIVETo elucidate the relationship between azoospermia factor(AZF) microdeletion of Y chromosome and azoospermia, the exact breakpoint of a severe Y-chromosome deletion was determined according to the physical map of AZF.

METHODSMultiplex polymerase chain reaction was used to amplify fifteen sequence tagged sites (STS), namely sY82, sY84, sY86 in AZFa, sY124, sY127, sY128, sY133, sY134, sY143 in AZFb, sY239, sY242 sY254, sY255 in AZFc, and sY145, sY152 in AZFd; sex-determining region Y(SRY) was taken as an internal control. And then sY82,sY86,sY85,sY84 were further analyzed using the sample of the patient who had Y-chromosome deletion by G band analysis to map the breakpoint at molecular level.

RESULTSAll 15 STS and sY85 were amplified in positive control while only sY82, sY86 were amplified in the clinical sample, thus the breakpoint was found to be between sY86 and sY85.

CONCLUSIONThis study on the patient provided the direct biomolecular evidence of the exact breakpoint of the severe Y-chromosome deletion and established the deletion map of acrocentric chromosome. It also proved that the patient's azoospermia was due to the deletion of AZF.

Azoospermia ; diagnosis ; genetics ; Chromosome Breakage ; Chromosome Deletion ; Chromosomes, Human, Y ; genetics ; Humans ; Male ; Polymerase Chain Reaction ; methods ; Reproducibility of Results ; Sensitivity and Specificity