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Results for “Chromosome Fragility”

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At least 145 records · Page 8Linked to original sources

PubMed1984

Chromosome fragility in Alzheimer's disease.

We present cytogenetic findings for 12 patients with Alzheimer's Disease (AD) mean age 75.8 +/- 6.01 years and 35 normal age and sex matched controls (mean age 74.8 +/- 4.04 years). The study, undertaken due to reports of increased fragments and chromosome breakage in individuals with AD, was performed blind on coded peripheral blood specimens and the allocation of AD or control was not known to the cytogenetic staff until the end of the study. Both the AD group and the controls have been very carefully selected and both underwent the same clinical assessment and screening procedures which included CT scanning. Chromosomes were analysed after 72 h cultures, using deprived medium TC199 which is known to enhance the appearance of fragile sites. A minimum of 50 cells was examined in each case and any rearrangement found was classified as ctg, csg , ctb , csb and the chromosome in which it occurred was recorded. Analysis of results showed that there was no statistically significant difference between the AD group and the controls for either the total occurrence of breaks, the type of aberration or the chromosome(s) involved. In both groups the commonest break was in 3p .

Aged↗

PubMed1982

[X chromosome fragility and effects of trimethoprim].

Severe clinical regression was observed in a patient carrier of a fragile X after treatment trimethoprime. This prompted us to examine the effect of this antibiotic in lymphocyte cultures: a dose ranging from 13 mg/l to 53 mg/l increases considerably the frequency of the Xq27 gap in four fragile-X patients; a dose of 13 mg/l allows a normal growth, without appearance of the Xq27 gap, in 19 normal, non-carrier subjects; a dose of 82 mg/l totally inhibits cell division in 10 normal, non carrier subjects. The reversibility of the blockade was demonstrated, either by washing out the trimethoprime before the 50th hour of incubation or by adding 5-formyl-tetrahydrofolate (0.125 mg/l). It is concluded that one of the steps of monocarbon metabolism is inhibited by trimethoprime. This antibiotic, which must be avoided when treating patients carrier of the fragile X can be utilized in vitro for cytogenetic investigations.

Cells, Cultured↗

PubMed1995

Characteristic chromosomal fragility of human embryonic cells exposed in vitro to aphidicolin.

The frequency and distribution of aphidicolin (APC)-induced common fragile sites (cfs) were analyzed in human embryonic cells of different origins. Embryonic lung fibroblasts (MRC-5), amniocytes (AMINO) and embryonic retina cells (HERO790) are as sensitive to the APC-induced clastogenic effect as peripheral lymphocytes, whereas embryonic kidney cells (HEK) seem more resistant to the induction of chromosomal gaps and breaks by the drug. Analysis of the distribution of fragile sites confirmed that the expression of specific APC-induced cfs varies in different cells and that the embryonic cell strains show a greater similarity among themselves than to lymphocytes. In addition, HEK, MRC-5, HERO790 and AMINO cells show specific APC induction of the cfs at the 1p31.2 chromosomal band, which seems to be a distinctive feature of the embryonic stage of cells.

Aphidicolin↗

PubMed1984

Chromosome fragility in Bloom's syndrome cell line GM 1492.

Chromosomal aberrations in skin fibroblasts from Bloom's syndrome cell line GM 1492 are described. As expected, the sister chromatid exchange (SCE) frequency was high. Four very common chromosomal rearrangements included dup( 6q ), t(13;15), dic(16), and del(11q). The nucleolar organizer regions (NOR) in the dicentric t(13;15) were active. The increased incidence of chromosomal markers suggests an evolution of clones in the cell line.

Bloom Syndrome↗

PubMed1985

The human genes for hemophilia A and hemophilia B flank the X chromosome fragile site at Xq27.3.

Two DNA recombinant clones, shown by separate studies to contain DNA sequences homologous to the genes coding for the human blood coagulation Factors VIII and IX, were hybridized in situ to metaphases or prometaphases derived from patients with the fragile-X syndrome and from a normal control. The results of these experiments indicate that (i) both genes are located in the subtelomeric region of the long arm of the human X chromosome flanking the fragile site at Xq27.3, (ii) the resolution of this localization is approximately 0.5% the length of the human haploid genome, i.e., 1.8 X 10(7) bp, (iii) the linear order of loci within the above region is Factor IX-fragile site-Factor VIII-Xqter. Both the localization and the linear order of these loci have been confirmed by Southern blotting studies using the same molecular probes and a panel of rodent-human somatic cell hybrids known to have retained different segments of the human X chromosome. The findings described herein and the knowledge that Factor IX deficiency recombines freely with at least two loci of the G6PD cluster support our hypothesis that the chromosomal region which includes the fragile-X site is normally a region of high meiotic recombination.

Chromosome Mapping↗

PubMed1986

Excessive chromosome fragility and abundance of sister-chromatid exchanges induced by UV in an Indian muntjac cell line defective in postreplication (daughter strand) repair.

Two UV-hypersensitive animal cell mutants defective in postreplication recovery (daughter strand synthesis) display quite different patterns of induced sister-chromatid exchange (SCE). One, an SV40-transformed Indian muntjac cell (SVM), shows extremely high frequencies of SCE after UV; induced exchanges can be measured after UV doses as low as 0.01 J/m2. This cell also displays exaggerated levels of induced and spontaneous chromosome aberrations. By contrast SCE rates in the Chinese hamster cell mutant, UV-1, are essentially normal. In both SVM and UV-1, however, there is a clear correlation between the cell density and spontaneous frequencies of SCE, a feature which could be related to the observed density-dependent rate of DNA maturation.

Animals↗

PubMed2025

Recessive FANCM cancer syndrome with high cancer risks, chemotherapy toxicity, chromosome fragility, and gonadal failure.

PURPOSE: Heterozygous FANCM variants have been associated with breast cancer. Only a few studies have examined other cancer types. Biallelic truncating variants have been linked to a Fanconi anemia (FA)-like cancer prone syndrome in case reports; however, the range of cancers and the risk estimates are lacking. METHODS: We studied the association of Finnish-enriched variants c.5101C>T p.(Gln1701Ter) and c.5791C>T p.(Arg1931Ter) with risk of any cancer and FA-related conditions in the FinnGen data with 500,348 individuals. RESULTS: Heterozygous c.5101C>T (N = 10,940) was associated not only with an increased risk of breast cancer (odds ratio = 1.24, P = 2.7 × 10-6) but also with risks of other cancer types, including hypopharyngeal (odds ratio = 3.98, P = 3.6 × 10-7), suggesting a risk effect wider than previously described. Homozygous c.5101C>T (N = 76) was associated with a high risk of breast, head and neck, gastrointestinal, gynecological, hematologic, skin, and lung cancer, whereas c.5791C>T was rare. Additionally, high recessive risks of ovarian dysfunction and hematologic side effects after cancer treatment were detected, but no risks of bone marrow failure or physical features of FA. CONCLUSION: Based on the pattern of risks associated with biallelic variants, we suggest a novel FANCM cancer syndrome that is separate from FA and other characterized cancer susceptibility syndromes.

Humans↗

PubMed2006

[Fragile X chromosomes and fragile X syndrome].

A case story is presented of a child diagnosed by chromosome analysis to be carrier of the fragile X chromosome at a low frequency in cultured lymphocytes. DNA analysis of the FMR1 gene at a later date did not reveal expansion of the FMR1 repeat, thereby refuting the diagnosis of fragile X syndrome. The discrepancy was discovered only when years later other family members came for counselling due to subsequent development of DNA-based analyses. It is recommended that persons and families investigated before DNA methods were used are re-evaluated and re-examined when relevant. Genetic diagnoses need regular revision, and information to families is important.

Adult↗

PubMed1975

Retinoblastoma. A model of hereditary fragile chromosomal regions.

Direct karyotyping of tumour cells from three familial and two sporadic cases of retinoblastoma revealed the existence of a Dq- marker chromosome. The hypothesis is launched that a specific region on the long arm of one of the D chromosomes is the site of a locus which is essential for the sustained differentiation of specialized retinal tissue and may be the site of other loci essential for the maturation of other embryonic tissues. Fragility of this region and its potentiality for breakage under the influence of various environmental insults could be the basic cytological event leading to the development of sporadic retinoblastoma. Mutants at these loci, including those of sustained differentiation, could be a less common operational event whereby some variants could enhance the fragility of their respective chromosomal region and thereby explain the genetic transmission of retinoblastoma in certain families. It is common for the critical functional disruption of the locus to precede the deletion which may then be considered the terminal event in the fragile region.

Child, Preschool↗

PubMed1980

Chromosome fragility and susceptibility of Bloom's syndrome fibroblasts to SV40 transformation.

A comparison of the frequencies of chromosomal aberrations and the rates of SV40 transformation was made using fibroblasts obtained from 2 patients with Bloom's syndrome (BS) and from a normal individual. BS cells were found to be more susceptible to chromosome damage, in confirmation of earlier reports, but surprisingly, BS cells were distinctly less prone to transformation.

Cell Transformation, Viral↗

PubMed1983