A genetically controlled type of cell death. There is an orchestrated collapse of a cell (see CELLS), typified by destruction of the cell's membrane; shrinkage of the cell with condensation of CHROMATIN; and fragmentation of DNA. The dead cell is then engulfed by adjacent cells. This process occurs without evidence of the inflammation normally associated with a cell's destruction by infection or disease. Apoptosis, first identified in 1972, is involved in biological activities including embryonic development, ageing and many diseases.

In adults, around 10 billion cells die each day – a figure which balances the number of cells arising from the body's stem-cell populations (see STEM CELL). As a person ages, apoptopic responses to cell DNA damage may be less effectively controlled and so result in more widespread cell destruction, which could be a factor in the onset of degenerative diseases. If, however, apoptopic responses become less sensitive, this might contribute to the uncontrolled multiplication of cells that is typical of cancers. Many diseases are now associated with changed cell survival: AIDS (see AIDS/HIV); ALZHEIMER'S DISEASE and PARKINSONISM; ischaemic damage after coronary thrombosis (see HEART, DISEASES OF) and STROKE; thyroid diseases (see THYROID GLAND, DISEASES OF); and AUTOIMMUNE DISORDERS. Some cancers, autoimmune disorders and viral infections are associated with reduced or inhibited apoptosis. Anticancer drugs, GAMMA RAYS and ULTRAVIOLET RAYS (UVR) initiate apoptosis. Other drugs – for example, NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) – alter the process of apoptosis. Research is underway to progress the development of new treatments, and to modify existing ones, for serious disorders such as cancer and degenerative nervous diseases.