Signs and symptoms
As a syndrome, this condition is poorly defined. Diagnostic criteria require one or more antisynthetase antibodies (which target tRNA synthetase enzymes), and one or more of the following three clinical features: interstitial lung disease, inflammatory myopathy, and inflammatory polyarthritis affecting small joints symmetrically. Other supporting features may include fever, Raynaud's phenomenon and "mechanics hands"-thick, cracked skin usually on the palms and radial surfaces of the digits.
The disease, rare as it is, is more prevalent in women than in men. Early diagnosis is difficult, and milder cases may not be detected. Also, interstitial lung disease may be the only manifestation of the disease. Severe disease may develop over time, with intermittent relapses.
It is postulated that autoantibodies are formed against aminoacyl-tRNA synthetases. The synthethases may be involved in recruiting antigen-presenting and inflammatory cells to the site of muscle or lung injury. The specific molecular pathway of the process awaits elucidation.
The most common antibody is "Anti-Jo-1" named after John P, a patient with polymyositis and interstitial lung disease detected in 1980. This anti-histidyl tRNA Synthetase antibody is commonly seen in patients with pulmonary manifestations of the syndrome. The following are other possible antibodies that may be seen in association with antisynthetase syndrome: Anti-PL-7, Anti-PL-12, Anti-EJ, Anti-OJ, Anti-KS, Anti-Zo, Anti-Ha-YRS, and Anti-SRP.
In the presence of suspicious symptoms a number of test are helpful in the diagnosis:
- Muscle enzymes are often elevated, i.e. creatine kinase
- Anti-Jo-1 antibody testing
- Muscle biopsy
- Pulmonary function testing
- Lung biopsy
In certain situations, testing of other antibodies, specific imaging (MRI, thoracic high resolution computed tomography), and swallowing evaluation may be needed.
Unfortunately, treatment for the anti-synthetase syndrome is limited, and usually involves immunosuppressive drugs such as glucocorticoids. For patients with pulmonary involvement, the most serious complication of this syndrome is pulmonary fibrosis and subsequent pulmonary hypertension.
Prognosis is largely determined by the extent of pulmonary damage.
- Bergoin, C.; Bure M; Tavernier JY; Lamblin C; Maurage CA; Remy-Jardin M; Wallaert B (June 2002). "The anti-synthetase syndrome". Revue des Maladies Respiratoires (in French). 19 (3): 371–374. PMID 12161705.
- Hervier, B.; Wallaert, B.; Hachulla, E.; Adoue, D.; Lauque, D.; Audrain, M.; Camara, B.; Fournie, B.; Couret, B.; Hatron, P. Y.; Dubucquoi, S.; Hamidou, M. (2010). "Clinical manifestations of anti-synthetase syndrome positive for anti-alanyl-tRNA synthetase (anti-PL12) antibodies: a retrospective study of 17 cases". Rheumatology. 49 (5): 972–976. doi:10.1093/rheumatology/kep455. ISSN 1462-0324. PMID 20156976.
- A man with fevers, arthrhalgias, and pulmonary infiltrates, L Christopher-Stine et al. NEJM 367: 2134-2147.
- Chatterjee S, Prayson R, Fraver C (2013). "Antisynthetase syndrome:Not just an inflammatory myopathy". Cleveland Clinic Journal of Medicine. 80 (10): 655. doi:10.3949/ccjm.80a.12171.
- Nishikai M, Reichlin M (1980). "Heterogeneity of precipitating antibodies in polymyositis and dermatomyositis". Arthritis Rheum. 23 (8): 881–888. doi:10.1002/art.1780230802. PMID 7406938.
- Lazarou IN, Guerne PA. Classification, diagnosis, and management of idiopathic inflammatory myopathies. J Rheumatol. 2013 May;40(5):550-64