Chromosomal Aberration

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Related to Chromosomal Aberration: aneuploidy, gene mutation

Chromosomal Aberration


(also called chromosomal mutation), any of a number of structural changes in chromosomes. These changes result from abnormal divisions within the chromosomes, generally accompanied by reunification of the resulting segments in combinations other than those existing in the original chromosomes.

Structural changes may occur within a single chromosome or between homologous and nonhomologous chromosomes. Such changes include the loss (deletion) or gain (duplication) of a segment of the chromosome, or the exchange (translocation) of a segment of the chromosome with another segment. In inversion, a chromosome segment is deleted, turned through 180°C, and reinserted at the same position on the chromosome. Deletion and duplication disrupt the gene balance, thus altering the organism’s characters. Inversions change only the sequence of the genes in the chromosome, whereas in translocations the genes of the shifted segment move to another linkage group. Neither inversions nor translocations disrupt the gene balance or alter the organism’s phenotypic characters.

When meiosis occurs among heterozygotes that contain one normal chromosome and one chromosome with an inversion, it is difficult for these chromosomes to come together, and crossing over between them does not take place or is infrequent. Aneuploid gametes often appear, and consequently heterozygotes are less fertile than homozygotes, in which both chromosomes of a given pair either have an inversion or are normal. Since heterozygotes have chromosomes in which translocation occurs, heterozygotes produce many aneuploid gametes and are consequently less fertile than homozygotes.

Chromosomal aberrations may arise spontaneously, but they are more likely to occur under the influence of physical and chemical factors. Minor deletions and duplications may result from irregular crossing over. Chromosomal aberrations play an important role in the evolution of organisms: duplications are the main cause of increases in the number of genes. Inversions and translocations may result in genetically isolated homozygous individuals that are more fertile than heterozygotes. In all chromosomal aberrations, the gene position effect is sometimes observed, in which a gene shifted to a new site on a chromosome exerts a different effect on the organism’s phenotype.

Chromosomal aberrations have a practical application in that they may be induced in order to change the linkage groups of genes to produce economically valuable characters in organisms.


References in periodicals archive ?
Box plot showing number of chromosomal aberrations on each group, control and treated, in P.
A total of 214 congenital CNS anomalies, including 28 among the cases with chromosomal aberrations (13%), were identified on prenatal ultrasonography and were studied (Supplemental Table 1; see supplemental digital content containing 8 tables at www.
22] The results of chromosomal aberration assay demonstrated no significant increase in the induction of structural chromosomal aberrations by ZnO nanorods upon comparison with that of control untreated groups.
To study whether the abnormal microtubule structures induce chromosomal aberrations, we used the oryzalin to depolymerize microtubules.
Table 1: Frequency of chromosomal aberrations in Imidazole treated cells No.
A total of 300 well spread metaphases per bulb were analyzed for chromosomal aberrations and 3000 cells were scored for mitotic index.
DO: Dissolved oxygen; BOD: Biological Oxygen Demand; TDS: Total Dissolved Solid; TSS: Total Suspended Solid, TS: Total Solid, Cd: Cadmium, Cr: Chromium, Pb: Lead, Ni: Nickel, Zn: Zinc, Fe: Iron Table 4: Types and frequencies of chromosomal aberrations induced by aqueous extracts of the three vegetables used for the study Concentration C- Chromosome Sticky mitosis bridge chromosome Control 0 0 0 0.
These results are consistent with the results of earlier studies, which showed that in regenerated plants from established diploid and tetraploid cultures of Italian ryegrass, chromosomal aberration was detected only from the tetraploid lines (Jackson and Dale, 1988).
highly significant percentages of chromosomal aberration were limited to 24 h after the heptaplatin administration.
Chromosomal aberration (CA) consisted of micronucleus lagging chromosomes chromosome fragment chromosome bridge etc.
The t(12;14)(q15;q23~q24) in leiomyoma: The most common chromosomal aberration in leiomyoma, seen in approximately 20% of karyotypically abnormal leiomyomas, is the characteristic translocation, t(12;14) (q15;q24), specifically associated with leiomyoma.