The Idiopathic Inflammatory Myositis (IIM) are heterogenous with distinct clinical phenotypes associated with specific myositis specific antibodies (MSA) and myositis associated antibodies (MAA).
To evaluate the frequency, pattern and associations of MSA/MAA in a large Indian cohort of IIM.
Adult and juvenile IIM (2017 ACR/EULAR criteria), were recruited in the MyoCite cohort between 2017and 2020 at a tertiary center in Northern India. Standardized clinical and laboratory variables were extracted from the database archive. Serum samples were evaluated for the presence of MSAs/MAAs by Line immunoassay and anti-nuclear antibodies (ANA) by Immunofluorescence assay (IFA). The prevalence and clinical associations of different MSA/MAAs were assessed.
MSA and MAAs were tested in 250 IIM patients (214 adults, 36 children) of age [40 (30
Myositis autoantibodies are seen in two-thirds IIMs and are associated with distinct clinical subsets. Jo-1 and non-Jo-1 ASS exhibit similar characteristics. The association of anti-TIF1 γ with malignancy was confirmed in adults. MSA/MAA were present in two-thirds of those with negative ANA and MSA were nearly always mutually exclusive.