Autoimmune lymphoproliferative syndrome

The autoimmune lymphoproliferative syndrome, ALPS, is characterized by an increase in the number of lymphocytes and is due to a malfunction of the immune system.

In the liver, the spleen and the lymphatic glands, many cells of defense accumulate unnecessarily, leading to an enlargement of the organs. It usually occurs as early as childhood. The cause is due to a premature disruption of programmed cell death (apoptosis). There is a mutation in four different genes, according to which the four types are differentiated.

ALPS type Ia: Affected is the gene FAS coding for the Fas receptor. It is a transmembrane protein and is expressed, inter alia, on activated T and B cells. Apoptosis is caused by the binding of the lingand FasL in the corresponding cells.

ALPS type Ib: The mutation is present in the gene coding for the lingand FasL. By altering the protein, it can not bind to the Fas receptor, and the signal for apoptosis is strangled.

ALPS Type II: This type has been identified very rarely. There is a mutation of the gene coding for caspases 8 and 10. The two caspases probably work downstream from the Fas receptor and modulate apoptosis.

ALPS type III: This type affects all diseases that are not subject to any of the above types.