Isochromosome

Isochromosome is a term used in genetics and refers to a malformation of a chromosome, a structural chromosome aberration in which a chromosome has lost one of his arms and this has been replaced by an exact copy of the other arm. Thus, the genetic information on the arm no longer contained is lost. The presence of an isochromosome in the genetic information can lead to disease.

The normal chromosome is duplicated during the S phase of the cell cycle. During the metaphase of mitosis (or meiosis I or II), the rows on sister chromatids along the center line. The affected chromosome is directed perpendicular to its normal position, and when the anaphase begins, the chromosome is separated so that two long and two short arms remain connected. The two resulting chromosomes are pulled by the microtubules in the two daughter cells. This leads to two cells where this chromosome arm, each having a too much or too little.

The cause of this malformation Miss a division of the centromere is assumed in metaphase. Instead parallel to the arms thereby the chromosome separates perpendicular to it, which no normal chromosomes occur in prophase I of meiosis, but isochromosomes.

A well-known example of a isochromosomale malformation is the Pallister - Killian syndrome with an additional isochromosome 12p; also from Turner 's syndrome there is a variant with an isochromosome.

• Chromosome