Antisynthetase Syndrome
Medically reviewed by Dr Ramani Arumugam, Consultant Rheumatologist ·
A cough and breathlessness that do not clear. Fingers that crack along the sides. Stiff, swollen joints. Legs that tire on the stairs. These can look like four separate problems, and patients are often sent to four separate clinics. In antisynthetase syndrome they are one condition, and one blood test can connect them. My role is to make that connection and to protect your lungs early.
Antisynthetase syndrome: understanding the condition
This one-page summary brings together the main features, the blood test, the lung checks and the treatment options. Tap the image to open it full size if the print is small on your phone.
View the full-size infographicUnderstanding antisynthetase syndrome
Antisynthetase syndrome is a rare autoimmune condition and one type of myositis. The immune system makes antibodies against enzymes that every cell uses to build proteins. These are called antisynthetase antibodies. The most common is anti-Jo-1. Others include anti-PL-7 and anti-PL-12. The condition is two to three times more common in women than in men.
The three main features
- Lungs. Inflammation and scarring of the lung tissue, called interstitial lung disease. It causes breathlessness and a dry cough, and it affects up to three in four patients. Sometimes it is the first or the only sign.
- Muscles. Inflammation that causes weakness in the shoulders, hips and thighs.
- Joints. Pain, stiffness and swelling, often in the small joints of the hands. It can look like rheumatoid arthritis.
Other signs
- Mechanic's hands. Thick, dry, cracked skin along the sides of the fingers and the palms. It looks like the hands of someone who does heavy manual work.
- Raynaud's phenomenon. Fingers or toes that turn white or blue and feel numb in the cold or under stress.
- Fever. About three in ten patients have fever that is not caused by infection.
These features do not all appear at the same time. That is why the diagnosis is often delayed.
Why it happens
We do not know the exact cause. As in other autoimmune conditions, the immune system mistakes the body's own tissue for a threat. It is not contagious, and it is not caused by anything you did.
How I reach the diagnosis
- A myositis antibody panel. This blood test looks for anti-Jo-1 and the other antisynthetase antibodies. A positive result with matching symptoms confirms the diagnosis.
- Muscle enzymes. Creatine kinase (CK) and related tests show whether the muscle is inflamed.
- Lung assessment. A high-resolution CT scan of the chest and lung function tests. I repeat the lung function tests over time to see whether treatment is working.
- Joint assessment. Examination, and musculoskeletal ultrasound where it helps to confirm joint inflammation.
- Muscle MRI, EMG or biopsy. In selected patients, when the muscle picture is unclear.
I work closely with a respiratory physician when the lungs are involved.
What treatment looks like
The lungs set the pace. Treatment starts early, and I usually start a second medicine together with steroids from the beginning.
- Corticosteroids. To bring the inflammation down quickly.
- Steroid-sparing medicines. Mycophenolate, azathioprine or tacrolimus, chosen according to how the lungs, muscles and skin are affected.
- Rituximab. An option when first treatments have not worked, especially for people with anti-Jo-1 antibodies.
- Cyclophosphamide. For severe lung disease.
- IV immunoglobulin (IVIG). In selected patients.
- Slow reduction. Flares tend to happen when medicines are reduced too quickly, so I taper carefully and watch the lungs as I do.
What you can do yourself
- Do not smoke or vape. Your lungs need every advantage.
- Report breathing changes early. New breathlessness, or a cough that is getting worse.
- Keep your vaccinations up to date. Treatment lowers your defences against chest infections.
- Keep your hands warm and moisturised. This helps Raynaud's and the cracked skin.
- Stay active. Follow an exercise plan from a physiotherapist.
- Take your medicines as prescribed. Never stop steroids suddenly.
What the future holds
The outlook depends mostly on the lungs. People with mild lung involvement often do well, and the condition can go into remission. Most people stay well only while they continue treatment, so long-term follow-up matters. Compared with other types of myositis, antisynthetase syndrome is less often linked to cancer.
Some of the information on this page is adapted from The Myositis Association: Antisynthetase Syndrome. It is general education and does not replace an individual medical assessment.
What antisynthetase syndrome is
Antisynthetase syndrome is a rare autoimmune condition defined by a specific group of antibodies, most often anti-Jo-1. It causes a combination of lung inflammation, muscle weakness and arthritis, often with cracked skin on the fingers (mechanic's hands), Raynaud's and fever.
Symptoms to look out for
Breathlessness on stairs or slopes that is new for you
A dry cough that lasts for weeks
Thick, cracked, rough skin along the sides of the fingers
Fingers that turn white or blue in the cold
Pain, stiffness or swelling in the hands, wrists or other joints
Difficulty climbing stairs, getting up from a chair or lifting your arms
Fever with no infection found
Tiredness and weight loss
Why this matters to a rheumatologist
The joint pain can look like rheumatoid arthritis, the cracked fingers like eczema, and the cough like a chest infection. Each piece is treated on its own while the lungs slowly scar. A rheumatologist is trained to see the pattern, request the antibody panel and treat the whole condition. The earlier the lungs are protected, the better the result.
Signs I would like you to seek care for
For emergency symptoms please seek urgent or emergency care first rather than waiting for a WhatsApp reply.
Breathlessness that is getting worse over days or weeks
A "chest infection" or "pneumonia" that has not cleared after treatment
A positive anti-Jo-1 or myositis antibody result
Interstitial lung disease on a CT scan with no clear cause
Arthritis together with cracked fingers, Raynaud's or muscle weakness
Difficulty swallowing
What a specialist review looks like
I look for all the features together: lungs, muscles, joints, skin and circulation. I review the scans and blood tests you already have and arrange the antibody panel and lung tests that are missing. I work with a respiratory physician to choose treatment. Then I follow your lung function, strength and blood tests at regular visits and adjust the plan as you improve.
Questions my patients often ask me
Anti-Jo-1 is the most common antisynthetase antibody. A positive result, together with symptoms such as breathlessness, muscle weakness or arthritis, points strongly to antisynthetase syndrome. It should be reviewed by a rheumatologist.
Speak with me
If you have a positive anti-Jo-1 result, or a mix of breathlessness, joint pain, cracked fingers and weak muscles that nobody has connected, WhatsApp my clinic. We can help you decide whether a rheumatology review is the right next step.
Other conditions I treat
This page is for general education only and does not replace medical advice. Please consult a qualified healthcare professional for diagnosis and treatment.