Question

Cri-du-chat (cry of the cat) syndrome occurs in human babies due to

• A. Deletion
• B. Duplication
• C. Inversion
• D. Simple translocation

Answer 1

The correct option is A Deletion

Loss of half of the short arm of chromosome 5 causes Cri-du-chat syndrome characterized by mewing like cry of newborn. Introduction of two breaks in the same chromosome and their reunion with omiting of an acentric fragment is called as deletion. Two breaks in the same chromosome followed by reattachment of middle section but in the inverted configuration causes inversion. Duplication is production of one or more copies of a gene or region of a chromosome caused by the breakage-fusion-bridge cycle or by crossovers within the loop of an inversion. Translocations are chromosome mutations involving break off the chromosome and rejoins it at a different location. Loss of half of the short arm of chromosome 5 causes Cri-du-chat syndrome characterized by mewing like cry of newborn, thus it is caused by deletion mutation.