Derivative chromosome

A derivative chromosome (der) is a structurally rearranged chromosome generated either by a rearrangement involving two or more chromosomes or by multiple aberrations within a single chromosome (e.g. an inversion and a deletion of the same chromosome, or deletions in both arms of a single chromosome). The term always refers to the chromosome that has an intact centromere. Derivative chromosomes are designated by the abbreviation der when used to describe a Karyotype. The derivative chromosome must be specified in parentheses followed by all aberrations involved in this derivative chromosome. The aberrations must be listed from pter to qter and not be separated by a comma.