Chromosomal Aberration

Chromosomal aberration refers to a change in number of chromosomes, can occur on one, or several, or all of the chromosomes within a nucleus. This is cause by the failure of sister chromatids to separate during anaphase of mitosis or the failure of homologous chromosomes to separate during anaphase I and/or II of mitosis. Aneuploidy refers to the loss or gain of single chromosomes but polyploidy refers to the increase in entire haploid sets of chromosomes. Structural aberrations are the result of chromosomal breaks that occur during meiosis or mitosis. This often leads to reshuffling of alleles on the chromosome. This is often caused by the deletion, duplication, translocation, inversion of several gene loci within chromosomes.