gene deletion

A gene deletion is the complete loss of a segment of a chromosome, which can lead to serious consequences. In a haploid cell, a deletion is lethal because essential genetic material is lost. In diploid cells, deletions are generally lethal or cause severe health issues. Even small deletions, too small to be seen with standard methods, can result in significant malformations and intellectual disability.12

For example, cri-du-chat syndrome in humans is caused by a deletion on chromosome 5, leading to a distinctive cat-like cry, severe intellectual disability, and an abnormally small head. The technique of fluorescence in situ hybridization (FISH) can detect small genetic deletions, even those involving just a few genes.123