The reassessment of a case of complex interchromosomal rearrangement after breakage at centromeric and telomeric regions, and the comparison with four other independently published cases suggested the existence of a new type of rearrangement. It would consist of: formation of an isochromosome after breakage at a centromeric region, duplication of the telomeric region of another chromosome, and reassociation of the nonduplicated arm of the first chromosome with the duplicated telomeric region of the second chromosome.