increased gross chromosomal rearrangement increased isochromosome formation 2012-11-14T14:05:03Z In S. pombe, isochromosome formation is most commonly observed with chromosome 3. A cell phenotype in which isochromosome formation occurs more frequently than in wild type cells. In isochromosome formation, one chromosome arm is lost and the other arm is duplicated in its place. FYPO:0001742 midori increased occurrence of isochromosome formation