Antiphospholipid syndrome affects both males and females, but a large percentage of primary APS patients are women with recurrent pregnancy loss. Specifically, the disorder affects three to five times as many women as men. APS can affect people of all ages, including children and babies. However, it usually affects adults aged 20–50. No defined racial predominance for primary APS has been documented. The statistical prevalence of APS is 1 in 1000. In Europe, APS may affect 2-5% of the general population. Some estimates indicate that as many as 1 in 5 cases of miscarriage or deep vein thrombosis are due to APS.

Antiphospholipid syndrome occurs when your body mistakenly produces antibodies against proteins that bind to phospholipids, a type of fat present in the body. Antibodies are produced by the body to fight off infections. In autoimmune disorders antibodies mistakenly target healthy tissue. In antiphospholipid syndrome, antibodies attack phospholipid-binding proteins. This can ultimately make the blood to clot abnormally. Primary antiphospholipid syndrome occurs when there no other conditions associated. Secondary antiphospholipid syndrome occurs if an individual has another autoimmune disorder, most commonly lupus.

The exact underlying reason why the body produces these antibodies is unknown. APS most likely results from the interaction of multiple factors including genetic, environmental and immunologic factors (multifactorial). Some individuals may have a genetic predisposition to developing the disorder. A genetic predisposition means that an individual carries a gene or gene(s) for a particular disorder, but that the disorder will not develop unless additional factors such as an environmental factor or additional genetic alteration occurs.

The specific symptoms will vary based upon the exact location of the blood clots, which can form in arteries or veins. In some people the disorder will cause infrequent, minor clots that do not cause significant problems, while in others frequent clots forming in critical blood vessel pathways can cause severe, even life-threatening complications. The disorder is often seen in young or middle-aged adults.

Any organ system is the body can potentially be affected and, consequently, the specific symptoms that can develop can vary significantly. For instance, deep vein thrombosis, which is the formation of blood clots in the large, deep veins of the legs is common. The legs may be painful and swollen. If a piece of the blood clot breaks off, it may travel to the lungs and cause a blockage in the lungs’ main artery, a condition known as pulmonary embolism.    

Blood clots that form in blood vessels serving the brain can cause stroke, mini-strokes (transient ischemic attacks), memory loss, seizures, jerky involuntary movements (chorea), and vision abnormalities.

In women affected by APS who become pregnant, there is an increased risk of recurrent miscarriage, preeclampsia, intrauterine growth restriction, and preterm birth.

Other potential findings include low platelet count (thrombocytopenia), heart valve disease, skin ulcers particularly in the legs, and livedo reticularis (discoloration of skin caused by dilation of capillary blood vessels).

Some individuals with antiphospholipid syndrome may have a history of headaches or migraines. Additional findings have been described based upon the exact location of blood clots. Abnormalities affecting the cardiovascular and gastrointestinal systems and the kidneys can also occur.

A diagnosis is mainly obtained through blood tests to check for abnormal clotting and for the presence of antibodies to phospholipid-binding proteins in individuals who have symptoms indicative of antiphospholipid syndrome.

Diagnostic tests for antiphospholipid syndrome are typically blood tests. Blood tests look for at least one of the following three antibodies in the blood: lupus anticoagulant, anticardiolipin, beta-2 glycoprotein I. APS cannot be detected during routine blood tests, so tests specifically designed to look for these antibodies need to be carried out. Two abnormal blood test results with at least a 12-week gap in between are required for APS to be diagnosed.

ELISA, or enzyme-linked ImmunoSorbent assay, can detect the presence of antibodies that target specific proteins in the blood, namely beta2-glycoprotein I or prothrombin.

As of now, there is no cure for antiphospholipid syndrome. Medical treatment usually consists of anticoagulants that reduce the blood's tendency to clot. This doesn't cure the disease but does help to prevent most serious complications. Individuals with mild disease may be treated with low doses of aspirin. Otherwise, stronger medications known as heparin or warfarin may be used.

With appropriate medication and lifestyle modifications, most individuals with antiphospholipid syndrome lead normal healthy lives. Survival rates of this disease are high. However, catastrophic APS is severe and can often cause life-threatening complications.

If antiphospholipid syndrome requires that a person takes anticoagulant medication, extra precautions should be taken to avoid injury and to avoid bleeding. Avoiding contact sports or other activities that could cause bruising or injury is recommended. Individuals may need to use a softer toothbrush and waxed floss, shave with an electric razor, and take extra care when using knives, scissors and other sharp tools since any cuts may cause large amounts of bleeding.

Affected individuals can also take certain steps to reduce the risk of developing blood clots. Effective ways of achieving this include not smoking, eating a healthy, balanced diet that is low in fat and sugar and contains plenty of fruit and vegetables, taking regular exercise and maintaining a healthy weight.

Individuals taking warfarin should avoid diets that are high in foods containing vitamin K because this vitamin can lessen the effect of warfarin.

Antiphospholipid Syndrome, Familial. Online Mendelian Inheritance in Man (OMIM) website. http://www.omim.org/entry/107320 Updated December 20, 2012. 

Antiphospholipid Syndrome. National Organization for Rare Disorders (NORD) website. Available at: https://rarediseases.org/rare-diseases/antiphospholipid-syndrome/. Updated 2011. 

Antiphospholipid Syndrome. Mayo Clinic website. Available at: http://www.mayoclinic.org/diseases-conditions/antiphospholipid-syndrome/basics/definition/con-20028805  Updated April 15, 2014. 

Brock CO, Brohl AS, Obican SG. Incidence, pathophysiology, and clinical manifestations of antiphospholipid syndrome. Birth Defects Res C Embryo Today. 2015;105(3) :201-208.

Erkan D, Aguiar CL, Andrade D, et al. 14th International Congress on Antiphospholipid Antibodies: task force report on antiphospholipid syndrome treatment needs. Autoimmun Rev. 2014;13(6):685-696.

Hughes G. Antiphospholipid Syndrome. Orphanet website. Available at : http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=GB&Expert=80  Updated July 2011 

Movva S, Carsons S, Belilos E. Antiphospholipid Syndrome. Emedicine website.

http://emedicine.medscape.com/article/333221-followup#e7

Updated March 24, 2015. 

Wong RC, Favaloro EJ. Clinical features, diagnosis, and management of the antiphospholipid syndrome. Semin Thromb Hemost. 2008;34(3)295-304.