Human genetic diseases such a cri-du-chat, angelman syndrome and prader-willi syndrome are the result of which type of chromosomal change?

Human genetic diseases such as Cri-du-chat, Angelman syndrome, and Prader-Willi syndrome are the result of deletion, a type of chromosomal abnormality. Deletion is also called gene deletion, deficiency, or deletion mutation. This abnormality is a mutation in which a portion of a chromosome or a sequence of DNA is missing during the replication of DNA.