Antisynthetase syndrome M33.1

Special form of dermatomyositis with as yet unexplained aetiology. Jo-1 syndrome or antisynthetase syndrome is named after autoantibodies against the Jo-1 antigen (Jo-1: = initials of the first patient John P.). This is identical to a histidyl transfer RNA synthetase in the cytosol.

w:m=2/3:1 (Mirrakhimov AE 2015)

In addition to muscle involvement, there is characteristically interstitial lung involvement (non-specific interstitial pneumonia (NISP)), which also determines the prognosis and clinical picture of the disease. Complaints include increasing exertional dyspnea, muscle weakness, macular or maculo-papular exanthema.

Palmar and plantar hyperkeratosis (hands like a mechanic, feet like a hiker) are not uncommon.

In addition, there may be clinical polyarthritis and other symptoms that resemble the clinical picture of other collagenoses. Like polymyositis and dermatomyositis, Jo-1 syndrome can present as so-called myositis overlap syndromes (in such cases, detection of U1-RNP antibodies).

Some cases of atypical antisynthetase syndrome (<20 cases) have been described with typical clinical symptoms of antisynthetase syndrome including mechanic's hands with only positive ANAs and positive anti-RO52 antibodies, but otherwise no other antisynthetase antibodies (Korsten P 2020).

The presence of serum autoantibodies against aminoacyl-tRNA synthetases (anti-ARS is involved in protein synthesis) is diagnostic for anti-synthetase syndrome (ASD). Antisynthetase antibodies also include: Anti-histidyl (anti-Jo-1), anti-threonyl (anti-PL-7), anti-alanyl (anti-PL-12), anti-isoleucyl (anti-OJ), anti-glycyl (anti-EJ), anti-asparaginyl (anti-KS)anti-Wa, anti-tyrosil (anti-YRS), anti-phenylalanyl transfer RNA synthetase (anti-Zo), and anti-SRP. Anti-Jo-1 is the most common anti-synthethase antibody (in 20-30% of patients with dermatomyositis and polymyositis) (Witt LJ et al. (2016).

In patients with anti-synthetase syndrome, compared to dermatomyositis and polymyositis, inflammatory myopathies, with which they may phenotypically overlap, there is a higher prevalence and increased extent of interstitial lung disease.

Good response to the administration of systemic glucocorticoids.

If necessary, additional administration of rituximab, azathioprine, methotrexate and cyclophosphamide. See below dermatomyositis.

A 64-year-old man had been complaining for 5 weeks of increasing stress dyspnea, muscle weakness, symmetrical pain in the wrists and a trunk marked macular non-itching exanthema.

In addition, there were acral, wart-like hyperkeratoses of the hands and flat hyperkeratoses in the areas of the soles of the feet exposed to pressure.

Clearly elevated were CRP, CK, BSG. Detection of anti-Jo-1 antibodies.

Under treatment with high-dose glucocorticoids the arthritic symptoms and exanthema disappeared within 4 days. Respiratory distress and hyperkeratosis also improved significantly within 14 days.

1. Cojocaru M et al. (2016) New Insights into Antisynthetase Syndrome. Maedica (Buchar) 11:130-135.
2. Johnston G (2017) Antisynthetase syndrome. Clin Med (Lond) 17:591.
3. Korsten P et al. (2020) Mechanic's hands in a patient with isolated anti-Ro52 antibodies: antisynthetase syndrome without antisynthetase antibodies. J Dtsch Dermatol Ges 18:147-148.
4. Mirrakhimov AE (2015) Antisynthetase syndrome: a review of etiopathogenesis, diagnosis and management. Curr Med Chem 22:1963-1975.
5. Witt LJ et al. (2016) The Diagnosis and Treatment of Antisynthetase Syndrome. Clin Pulm Med 23:218-226.