What is an isochromosome?

An isochromosome is defined as a chromosome that has identical arms due to the deletion and replacement of one of its arms. This process results in the formation of a chromosome that consists of two copies of one of its arms (either short or long) and a deletion of the corresponding section on the opposite arm. For example, if we consider a chromosome that normally has one short arm and one long arm, an isochromosome would have two short arms or two long arms, leading to genetic imbalances if one arm is missing. This phenomenon can significantly impact gene expression and contribute to various genetic disorders. Understanding isochromosomes is important in genetics and cytogenetics, as they can play a role in conditions such as Turner syndrome.