Isochromosome

Isochromosome (pronounced: /ˌaɪsoʊˈkroʊməˌsoʊm/) is a type of chromosome abnormality where one arm of the chromosome is missing and the other arm is duplicated, resulting in a chromosome consisting of two short arms (p arms) or two long arms (q arms).

Etymology

The term "isochromosome" is derived from the Greek words "isos" meaning equal, and "chroma" meaning color, referring to the identical arms of the chromosome.

Formation

Isochromosomes are formed through a misdivision of the centromere, the part of a chromosome that links sister chromatids. During cell division, instead of the centromere dividing along its width (as it normally does), it divides along its length. This results in one chromosome with two copies of one arm and no copies of the other arm.

Clinical Significance

Isochromosomes can result in diseases due to the duplication of one arm and the loss of the other. For example, an isochromosome of the long arm of the X chromosome (i(Xq)) is one of the most common abnormalities in Turner syndrome, a condition that affects females and is characterized by short stature and infertility.