Chromosomal duplication



Chromosomal duplication occurs when a section of DNA is accidentally duplicated when a chromosome is copied. A duplication may occur as the result unequal crossing over, the mispairing and exchange of DNA between genetically similar, nonhomologous chromosome regions that results in duplication of DNA in each daughter cell.

Bloom and Rett syndrome are caused by chromosomal duplications.

The duplicated chromosomes are attached to each other original chromosomes during mitosis.

Deletions are often lethal and similar to aneuploids, disrupting gene balance. Deletion heterozygotes form deletion loops at meiosis (Mark Fox, 2007).