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PubMed1989

Chromosomes in myelodysplastic syndrome: structural abnormalities of chromosome 11. Czechoslovak MDS Cooperative Group.

In a series of 121 consecutive patients with a myelodysplastic syndrome (MDS), studied in two laboratories, of which 87 (71.9%) had abnormal karyotypes, twelve had a structural abnormality of the long arm of chromosome 11 (13.8%). There were six deletions, one ring chromosome and five reciprocal translocations, all involving a chromosome band 11q23. Of these twelve patients, five had a refractory anemia (RA) and seven a refractory anemia with excess of blasts (RAEB). RA was associated more frequently with 11q deletions as the sole abnormality, while translocations or multiple chromosome abnormalities were commonly associated with RAEB. The study shows that the 11q aberrations represent frequent structural chromosome rearrangements in MDS.

Bone Marrow↗
PubMed1997

Chromosomal aberrations in vitro induced by aneugens.

Various aneugens were reported to induce structural chromosomal aberrations beside their influence on cell division and their aneugenic potential To asses, whether a relationship between disturbance of cell division and clastogenic potential exists, CHO cells were treated with the well-known aneugens colcemid, colchicine and vincristine and investigated for the induction of structural chromosomal aberrations, polyploid cells and alterations in mitotic index. At low and intermediate concentration, all compounds induced polyploidy and an increase in mitotic index, but no structural aberrations at all. However, at high concentrations, colcemid and colchicine both induced numerous structural chromosomal aberrations in diploid cells. Colchicine was also clastogenic in tetraploid cells. Vincristine did not induce structural chromosomal aberrations in diploid cells, but in tetraploid cells. The clastogenic effects showed a clear-cut threshold with all three compounds. Furthermore, it was found that the tetraploid condition in CHO cells is generally accompanied by an increase in structural chromosomal aberrations, in vehicle controls as well as in cultures treated with the aneugens. Nevertheless, this study demonstrates that for the three aneugenic compounds tested, no direct relationship between compound induced disturbance of cell cycle and compound induced structural chromosomal aberration incidence exists.

Aneuploidy↗
PubMed1997

The incidence of uniparental disomy associated with intrauterine growth retardation in a cohort of thirty-five severely affected babies.

OBJECTIVE: Our purpose was to screen for uniparental disomy 35 babies with idiopathic intrauterine growth retardation < 5th percentile. STUDY DESIGN: The placenta and the baby's blood were conventionally karyotyped. Deoxyribonucleic acid from the parents, the baby's blood, and the placenta were then screened for uniparental disomy for 12 candidate chromosomes with use of chromosome-specific polymorphic deoxyribonucleic acid markers. RESULTS: Two cases of maternal uniparental disomy for chromosome 16 were found associated with confined placental mosaicism for chromosome 16. No other uniparental disomy was found for any of the 12 chromosomes tested. Four structural chromosome abnormalities were also found in this cohort through standard karyotyping. CONCLUSION: Uniparental disomy for the chromosomes tested does not explain the etiology of the majority of cases of intrauterine growth retardation < 5th percentile. Maternal uniparental disomy for chromosome 16 accounts for 5% of this cohort. Structural chromosomal abnormalities are also much higher than expected at 11%.

Chromosome Aberrations↗
PubMed2001

[Clinical and genetic consequences of ring chromosome, a structural genome mutation].

Ring chromosome is a peculiar genetic anomaly which may cause phenotypic abnormalities even without a loss of genetic material. The ring formation of chromosome ends induces difficulties in the sister chromatid separation at cell division, resulting in increased cell death rate through the generation of secondary aneuploid cells. Based on the in vitro analyses of own cases and a review of more than 200 case reports published in the literature, the author presents some conclusions on "ring syndrome", a non-specific clinical manifestation of ring formation of any chromosome, consisting of the lack of (or poorly expressed) organic manifestations, mild or borderline mental retardation, and a severe growth failure which is not explained by organic, biochemical, or endocrine findings. It is also suggested that the phenotypic manifestation of a ring chromosome is even less expressed when the ring is transmitted to the next generation. Based on observations of ring behaviour and the clinical phenotypes in a 3-generational family with a mosaic supernumerary ring, it is not unrealistic to assume that there is a transgenerational increase in the severity of the clinical manifestation resulting from a less efficient elimination process against the ring (cytogenetic anticipation).

Anticipation, Genetic↗
PubMed1977

[New findings on the structure of chromosomes (author's transl)].

The structural element of eukaryotic chromosomes is the chromatin fibre consisting of histones and DNA. The chromatin fibre is about 100--200 A thick. One chromatid is built up from one chromatin fibre running through from one end to the other and laid in numerous irregular foldings. The chromatin fibre is a chain of nucleosomes. These are globular histone bodies around which the DNA winds. Nucleosomes can be observed in isolated chromatin fibrils as well as in thin sections of chromosomes after different modes of fixation. Prophasic chromosomes or early premature condensed chromosomes are thin uncoiled threads. With chromosome condensation a major coiling is seen. No constant regular arrangement of the chromatin fibril besides the major coils is observed. A rather diffuse decondensation takes place in ana- and telophase.

Animals↗
PubMed1992

Structure and chromosomal location of the human granulin gene.

Granulins are a family of cysteine rich polypeptides some of which have growth modulatory activity. We showed previously that the granulins are encoded within the same precursor consisting of seven granulin domains arranged in tandem. Here we report the chromosomal location and structural organization of the protein coding region of the granulin gene. The granulin gene was assigned to chromosome 17 using DNA from human-hamster somatic cell hybrids. The protein-coding region of the granulin gene was shown to comprise 12 exons covering about 3700 bp. Each tandem granulin repeat is encoded by two non-equivalent exons, a configuration unique to the granulins that would permit the formation of hybrid granulin-like proteins by alternate splicing.

Alternative Splicing↗
PubMed1986

Lymphocyte malignancy and chromosome 14: structural aberrations involving band q11.

Five patients with lymphocytic malignancies were found to have structural aberrations of chromosome 14, all involving band q11. The malignant cells of all five cases were analyzed by immunofluorescence to establish immunologic phenotypes. Three patients had T lymphoblastic lymphoma/leukemia with mediastinal masses (cases 1, 2, and 3); one patient had peripheral T cell lymphoma (case 4); and one patient had acute lymphocytic leukemia, common acute lymphoblastic leukemia antigen positive (case 5). Although aberrations of chromosome 14 frequently are associated with lymphocytic malignancies, these abnormalities most often result in extra material on the long arm, 14q+. However, none of the five patients reported here had a 14q+. Cases 1 and 2 had t(9;14)(q34;q11) and t(11;14)(p11 or 13;q11), respectively. Case 3 showed del(14)(q11), and cases 4 and 5 showed inv(14)(q11q32). Structural aberrations resulting in 14q- and inv(14) appear to occur infrequently. The five cases in this report, in conjunction with those found in the literature, indicate a strong association between breaks at 14q11 and T lymphocytic malignancies.

Adult↗
PubMed1983

Structure and organization of rRNA operons in the region of the replication origin of the Bacillus subtilis chromosome.

Structure and organization of two complete ribosomal RNA (rRNA) gene sets, rrnO and rrnA, were determined for the first time in Bacillus subtilis. They are located at the region of the replication origin of the chromosome. Each set constitutes a single operon of: two tandem promoters - leader sequence - 16S rRNA gene - Ile-tRNA gene - Ala-tRNA gene - 23S rRNA gene - 5S rRNA gene - termination signal. The first promoter (P1) of rrnO differs from that of rrnA in sequence and function. P1 of rrnO was used very little for transcription either in vivo or in vitro while P1 was predominantly used in rrnA. A putative transcript of the entire operon was determined and constructed into a secondary structure. Analysis of in vivo transcripts by S1 mapping revealed primary processing sites at the loop and stem structure of 16S rRNA in rrnO and rrnA. A unique sequence in the leader region of rrnO can be formed into a highly complexed secondary structure and affects processing of mature 16S rRNA. The sequences of the two spacer tRNA genes are highly conserved between B. subtilis and Escherichia coli.

Bacillus subtilis↗
PubMedDate not supplied

Proto-oncogenes, growth factor genes, receptor genes, differentiation genes and structural rearrangements in human cancer.

Information on chromosomal structural rearrangements in leukemia and solid tumors was retracted from a computerized databank and the literature. A binomial test procedure was used to determine the statistical significance of the observed numbers of breaks. Some 131 human cancer-specific chromosomal structural rearrangements were also taken from the literature. The results showed that breakage and deletion occurred preferentially in bands known to contain proto-oncogenes, growth factor genes, receptor genes and differentiation genes. Therefore, chromosomal structural rearrangements could be used to find and map new genes involved in the genesis and/or progression of neoplasia.

Cell Differentiation↗
PubMedDate not supplied

[Chromosome scaffold and structural integrity of mitotic chromosomes].

Chromosome scaffold represents a continuous protein substructure revealed in isolated metaphase chromosomes after harsh extraction. According to postulates of the widespread radial loop model the scaffold plays an important role in the formation and maintenance of structural integrity of the mitotic chromosomes. Here, the data concerning the structure and major components of the chromosome scaffold are presented. The experiments suggesting that the scaffold represents a system of discrete linker proteins and the data about high mobility of scaffolding proteins are discussed. Furthermore, the data about higher-level chromatin structures (elementary chromonema and 200-250 nm fibers) and behavior of scaffolding proteins are compared. The results presented agree with the idea that at the present stage it is possible to discriminate chromatin complexes, whose structural integrity is not maintained by the chromosome scaffold.

Chromatin↗
PubMed1994

Multiple chromosomes in bacteria: structure and function of chromosome II of Rhodobacter sphaeroides 2.4.1T.

Although multiple chromosomes occur in bacteria, much remains to be learned about their structural and functional interrelationships. To study the structure-function relationships of chromosomes I and II of the facultative photosynthetic bacterium Rhodobacter sphaeroides 2.4.1T, auxotrophic mutants were isolated. Five strains having transposon insertions in chromosome II showed requirements for p-aminobenzoic acid (pABA)-dihydroxybenzoic acid (dHBA), serine, thymine, uracil, or histidine. The His, Thy, and pABA-dHBA mutants reverted to prototrophy at low frequency and concordantly lost their transposon insertions from the genome. The Ser, Ura, and pABA-dHBA mutants were complemented by cosmids that carried the region of chromosome II where the transposon insertions were located. The cosmids used for complementation analysis were selected, on the basis of map position, from a set of overlapping clones that had been ordered by a combination of hybridization and restriction endonuclease mapping. These experiments provide the basis for detailed studies of the structure, function, and interaction between each chromosome, and they demonstrate at this early stage of investigation that no fundamental differences exist between each chromosome.

4-Aminobenzoic Acid↗
PubMed1987

Extra structurally abnormal chromosomes (ESAC) detected at amniocentesis: frequency in approximately 75,000 prenatal cytogenetic diagnoses and associations with maternal and paternal age.

We analyzed rates of extra structurally abnormal chromosomes (ESAC) detected in prenatal cytogenetic diagnoses of amniotic fluid reported to the New York Chromosome Registry. These karyotypes include both extra unidentified structurally abnormal chromosomes (EUSAC)--often denoted as "markers"--and extra identified structurally abnormal chromosomes (EISAC). The rate of all EUSAC was 0.64/1,000 (0.32-0.40/1,000 mutant and 0.23-0.32 inherited), and that of all EISAC was 0.11/1,000 (0.07/1,000 mutant and 0.04/1,000 inherited). The rate of all ESAC was approximately 0.8/1,000-0.4-0.5/1,000 mutant and 0.3-0.4/1,000 inherited. Mean +/- SD maternal age of mutant cases was 37.5 +/- 2.9, significantly greater than the value of 35.8 years in controls. A regression analysis indicated a rate of change of the log of the rate of about +0.20 with each year of maternal age between 30 and 45 years. When paternal age was introduced, the maternal age coefficient increased to about +0.25--close to that seen for 47, +21--but the paternal age coefficient was -0.06. After being matched for maternal age and year of diagnosis, the case-control difference in paternal age for 24 mutant cases was -2.4 with a 95% confidence interval of -4.6 to -0.1 years. In a regression analysis of the effects of both parental ages on the (log) rate, the maternal age coefficient was +0.25 and the paternal age coefficient was -0.06. These results are consistent with a (weak) negative paternal age effect in the face of a strong maternal age effect. Since ESAC include a heterogeneous group of abnormalities, the maternal age and paternal age trends, if not the result of statistical fluctuation or undetected biases, may involve different types of events. Data in the literature suggest that chromosomes with de novo duplicated inversions of 15p have a strong maternal age effect (but little paternal age effect). Such chromosomes, however, do not account for the active maternal age trends seen in the data analyzed here. Inherited ESAC exhibited no such trends.

Adolescent↗
PubMed2003

Application of spectral karyotyping to the analysis of the human chromosome complement of interspecies somatic cell hybrids.

Mouse-human somatic cell hybrids have been extensively used in the molecular genetic dissection of human disease-related chromosome rearrangements because of their ability to selectively and randomly eliminate human chromosomes. This technology allows the isolation of structural chromosome abnormalities, which then allows determination of the precise molecular address of chromosome breakpoints associated with deletions and translocations, down to the nucleotides involved. The main confounding problem with the analysis of somatic cell hybrids is determining the exact chromosome complement unequivocally and quickly. Spectral karyotyping can identify each of the individual human chromosomes in a normal metaphase spread, as well as structural chromosome rearrangements-although, because of potential cross-hybridization between the human probe and mouse DNA sequences during the hybridization reaction, it has not been determined whether the same analysis will selectively identify human chromosomes on a mouse background. We show (to our knowledge, for the first time) that, under modified conditions of chromosomal in situ suppression hybridization, the standard spectral karyotyping probe does not cross-react with mouse chromosomes and can be used to identify subtle structurally rearranged chromosomes in hybrid cells. This analysis allows for the rapid and unequivocal identification of the human chromosome complement in these hybrids, as well as structural chromosome rearrangements that occur between mouse and human chromosomes that might otherwise confound the analysis.

3T3 Cells↗
PubMed1995

Fifty probands with extra structurally abnormal chromosomes characterized by fluorescence in situ hybridization.

Extra structurally abnormal chromosomes (ESACs) are small supernumerary chromosomes often associated with developmental abnormalities and malformations. We present 50 probands with ESACs characterized by fluorescence in situ hybridization using centromere-specific probes and chromosome-specific libraries. ESAC-specific libraries were constructed by flow sorting and subsequent amplification by DOP-PCR. Using such ESAC-specific libraries we were able to outline the chromosome regions involved. Twenty-three of the 50 ESACs were inverted duplications of chromosome 15 [inv dup(15)], including patients with normal phenotypes and others with similar clinical symptoms. These 2 groups differed in size and shape of the inv dup(15). Patients with a large inv dup(15), which included the Prader-Willi region, had a high risk of abnormality, whereas patients with a small inv dup(15), not including the Prader-Willi region, were normal. ESACs derived from chromosomes 13 or 21 appeared to have a low risk of abnormality, while one out of 3 patients with an ESAC derived from chromosome 14 had discrete symptoms. One out of 3 patients with an ESAC derived from chromosome 22 had severe anomalies, corresponding to some of the manifestations of the cat eye syndrome. Small extra ring chromosomes of autosomal origin and ESACs identified as i(12p) or i(18p) were all associated with a high risk of abnormality.

Abnormalities, Multiple↗
PubMed1997

Human synaptotagmin V (SYT5): sequence, genomic structure, and chromosomal location.

We have determined the sequence, genomic structure, and chromosomal location of the human synaptotagmin V (SYTV) gene. The human SYTV gene encodes a 386-amino-acid product which is 91% identical to rat Syt V. The human SYTV open reading frame is interrupted by seven introns which can be alternatively spliced. Human SYTV was found to lie very close to SYTIII on chromosome 19q13.4 by PCR analysis of somatic cell hybrid DNA and by DNA hybridization to arrayed cosmids of the chromosome 19 metric physical map. This provides the first report of linked synaptotagmin genes.

Amino Acid Sequence↗
PubMed1981

Activity of steroid sulfatase in fibroblasts with numerical and structural X chromosome aberrations.

In cultured fibroblasts of patients with numerical and structural X chromosome aberrations the activity of steroid sulfatase (STS) is correlated with the number of functional STS gene copies. While normally, this X-linked gene is not inactivated, our data suggest that it may be subject to inactivation when carried on a structurally altered X-chromosome. Similar inactivation patterns have been reported earlier for the Xg locus which, like STS, is located on the distal portion of Xp.

Cells, Cultured↗