DNA laddering is a phenomenon seen in laboratory tests; it is a sensitive indicator of programmed cell death, specifically of apoptosis. It was first described in 1980 by A. H. Wyllie at the University of Edinburgh Medical School.[1]
Endonuclease activation is a characteristic feature of apoptosis. This degrades genomic DNA at internucleosomal linker regions and produces 180- to 185- base-pair DNA fragments. On Agarose gel electrophoresis, these give a characteristic "laddered" appearance. The dying cell's morphological changes are short-lived and difficult to detect. DNA laddering has therefore become a sensitive method to distinguish apoptosis from ischemic or toxic cell death.[2]