What diseases and conditions are associated with antiphospholipid syndrome (APS)?

Updated: Nov 24, 2020
  • Author: Suneel Movva, MD; Chief Editor: Herbert S Diamond, MD  more...
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APS is an autoimmune disorder of unknown cause. The search for possible triggers has uncovered a wide array of associated autoimmune or rheumatic diseases, infections, and drugs that are associated with the LA or aCL antibodies. These associations may ultimately provide a clue to the etiology of APS. A considerable percentage of persons with certain autoimmune or rheumatic diseases also have aPL antibodies.

Common autoimmune or rheumatic diseases and the percentage of affected patients with aPL antibodies are as follows (note that these represent percentages of patients with aPL antibodies, rather than the clinical syndrome of APS [13] ):

  • SLE - 25-50%
  • Sjögren syndrome - 42%
  • Rheumatoid arthritis - 33%
  • Autoimmune thrombocytopenic purpura - 30%
  • Autoimmune hemolytic anemia - Unknown
  • Psoriatic arthritis - 28%
  • Systemic sclerosis - 25%
  • Mixed connective-tissue disease - 22%
  • Polymyalgia rheumatica or giant cell arteritis - 20%
  • Behçet syndrome - 20%

Infections associated with APS include the following [14] :

  • Syphilis
  • Hepatitis C 
  • HIV infection
  • Human T-cell lymphotrophic virus type 1 infection
  • Malaria
  • Bacterial septicemia

Drugs associated with APS include the following:

  • Cardiac - Procainamide, quinidine, propranolol, hydralazine
  • Neuroleptic or psychiatric - Phenytoin, chlorpromazine
  • Other - Interferon alfa, quinine, amoxicillin

In addition, certain vaccines have been associated with APS. For example, vaccination with tetanus toxoid may trigger the formation of antibodies that cross-react with βbeta-2 glycoprotein I, due to molecular mimicry between the two molecules. [15]

 Genetic predisposition may be involved, as follows:

  • Relatives of persons with known APS are more likely to have aPL antibodies. One study showed a 33% frequency.
  • An association has been found between aCL antibody and carriage of certain HLA genes, including  DRw53, DR7 (mostly in people of Hispanic origin), and  DR4 (mostly in whites).

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