What is Antisynthetase Syndrome?
Antisynthetase Syndrome (also known as AS syndrome) is a nervous system disease which is grouped under Idiopathic inflammatory myopathy. It results in a chronic autoimmune condition which affects the working of muscles and various other parts of the body. Antisynthetase Syndrome is mediated by the immune system directly, which basically means that it is caused due to the abnormal functioning of the immune system. It is usually caused due to the presence of certain antibodies, which target specific proteins in the body. It has a wide range of symptoms whose severity varies from patient to patient which include inflammation of the muscles and joints, numbness of fingers and toes, with eventual thickening and cracking of the skin (Raynaud phenomenon) and interstitial lung disease. Along with these, individuals suffering from Antisynthetase Syndrome also have non-specific untraceable symptoms such as fatigue, sleeplessness, fever and weight loss. Although the exact cause is still not completely understood it often occurs with an uncommon inflammatory muscle disease like dermatomyositis.
Symptoms of Antisynthetase Syndrome
Symptoms of Antisynthetase Syndrome vary from person to person and hence its effect on every individual can be very different. This can be explained by the following example; in a certain case the affected individual might have inflammation of the lungs, but no muscle involvement and vice versa.
The three major symptoms of Antisynthetase Syndrome are
However, it is not likely that all three symptoms of Antisynthetase Syndrome might develop at the same time. The major ways in which it affects the muscles include muscle pain, inflammation and stiffness. These can eventually lead to muscle weakness. Inflammation of joints on the other hand might result in stiffness and pain in various joints, all at the same time (polyarthritis). This however doesn’t affect the surrounding bone. Rarest of the three major symptoms of Antisynthetase Syndrome is lung disease, which involves inflammation and scarring of lungs around the alveoli. It increases progressively if left untreated and eventually affects the breathing process, causing difficulty in breathing due to shortage of oxygen, which in extreme cases might result in respiratory failure.
Other non-specific symptoms include rashes, weight loss, sleeplessness, fatigue and fevers. Discoloration of hands along with thickening and cracking of skins can also occur. This can be accompanied by numbness or a sharp feeling in the finger and toes in response to extreme temperatures. The fingers and toes might also turn light blue or white.
Causes of Antisynthetase Syndrome
Antibodies are proteins which help an individual fight against disease causing foreign organisms. The exact cause of Antisynthetase Syndrome is not known however it is believed to be caused due to autoantibodies, which mistakenly attack the normal tissues. The aminoacyl-tRNA synthetase enzyme is targeted by these autoantibodies. The function of this enzyme is to cause biochemical reactions in the body which in turn regulates the production of proteins, which are important for the overall development and well-being of the individual. However not always do people who develop these autoantibodies develop symptoms to antisynthetase syndrome. Anti-Jo1 is the most common autoantibody which is associated with people affected with antisynthetase syndrome. The various other autoantibodies include anti-PL7, anti-PL12, and anti-KS to name a few. They are mainly produced under the influence of events like a viral infection or on intake of certain drugs. These events result in a response by the immune system, which results in the subsequent production of these antibodies.
Disorders Related To Antisynthetase Syndrome
The following disorders might have symptoms similar to antisynthetase syndrome, and hence a comparison between them might be helpful for proper diagnosis:
- Rheumatoid Arthritis– It is a progressive disorder of the joints which results in inflammation of both joints symmetrically. The joints become soft and warm with time, and sensitive to touch. The smaller joints are affected first. It also results in other minor symptoms like fever and fatigue. This is caused due to fallacy in the immune system, as a result of which the healthy tissues of the body are affected.
- Interstitial Lung Disease– This is caused mainly due to the inflammation of the alveoli of the lungs. There are more than 200 different cases associated with similar interstitial lung problems.
- Inflammatory Myopathies- This is caused due to the chronic inflammation of the muscles, and results in muscle weakness, stiffness along with pain. The extent of pain varies from patient to patient
Now as it can be seen similar symptoms are shown in individuals suffering from antisynthetase syndrome. Hence it is essential to differentiate between them through blood tests and other medical procedures as has been explained in the next section. It is important to understand that although the symptoms are the same, the root cause for it in a person suffering from antisynthetase syndrome is merely the formation of autoantibodies which attack the healthy tissues. Therefore in order to diagnose a person efficiently it is important to differentiate between them, so as to ensure that the correct medication is being provided, in order to recover early.
Diagnosis of Antisynthetase Syndrome
Diagnosis is mostly dependent on the type of symptoms seen, and the patient’s medical history. This is followed by a thorough clinical evaluation for the presence of autoantibodies, against the enzyme aminoacyl-tRNA synthetase.
Blood tests are done to check the presence of these autoantibodies; however the presence of the autoantibodies does not necessarily confirm the development of the syndrome. There are different criteria set for the confirmation of the syndrome by different organizations however none are universally accepted. Different physicians usually have their own set standards, depending upon the symptoms and their own understanding of the case. The development of the syndrome is confirmed based on the number of symptoms which are in terms with the expected symptoms. If any 2 of the three major symptoms are present then it is assumed that the individual is suffering from Antisynthetase Syndrome. On the other hand, if at least any 3 major/minor symptoms are confirmed even then the person is said to be diagnosed with the syndrome. The major symptoms include lung/muscle/joint disorders, while the minor symptoms include the remaining ones which include paleness and insensitivity of fingers and toes, fever, fatigue to name a few.
Muscle damage can be identified through blood test, based upon the blood levels of kinase and aldolase as elevated blood levels indicate muscle damage. Computerised Tomography (CT) scan and X-Ray can be used to identify lung disorders. These days even high resolution CT scanning techniques are there, which can be used to test for minute pulmonary disorders. The pulmonary tests can then be used to get a rough estimate on how effectively the lungs are working.
Treatment of Antisynthetase Syndrome
Usually treatment for Antisynthetase Syndrome requires a team of specialists. These include pulmonologists (lung disease), orthopedists (skeletal and muscle disease) and immunologists. Along with this even psychologists are required to provide mental support to the patient and the family.
The basic method of treatment of Antisynthetase Syndrome involves usage of drugs which help to cure the symptoms, these in turn with time help to remove the syndrome. Along with that physical therapy is also recommended to help treat the muscular and skeletal problems.
The various drugs in order to treat the symptoms of Antisynthetase Syndrome are:
- Corticosteroids– which help to suppress the activity of the immune system.
- Hydroxychloroquine – used to treat skin symptoms
- Glucocorticoids– to suppress skeletal muscle disorders
- Physical therapy– for muscular and skeletal disorders.
However, drugs must be taken as per the doctors’ guidelines.
Prognosis of Antisynthetase Syndrome
The recovery from Antisynthetase Syndrome is quicker if the symptoms only involve muscular or skeletal disorders. This can be overcome by immunosuppressive therapy and glucocorticoids. The case worsens when the Antisynthetase Syndrome patient suffers from a lung disease. It depends more on the severity and the longevity of the lung disease. If the disease is progressive recovery time is increased on the other hand in case of non-progressive lung disease the prognosis is quicker. Poor prognosis is usually associated with old age (above 60), presence of tumors and weak immune system.
Antisynthetase Syndrome is a relatively rare medical condition whose effects and diagnosis are still under progress. It is twice more likely to affect females as compared to males. The age of onset varies from early teenage to the late fifties. The exact nature of the disorder is yet unknown. Hence the diagnosis is mainly restricted to the diagnosis of its individual symptoms. Along with it nutritional support and treatment (like administration of drugs an immunosuppressive therapy) are to be followed to cope up with the syndrome.
- Witt, L., Curran, J., & Strek, M. The Diagnosis and Treatment of Antisynthetase Syndrome. Clinical Pulmonary Medicine, (2016). 218-226. doi: 10.1097/cpm.0000000000000171