Experts highlight myositis-specific and associated autoantibody (MSA/MAA) testing in diagnosing idiopathic inflammatory myopathy

A study published in the Journal of Translational Autoimmunity by experts has acknowledged the need for identification of myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) in diagnosing and characterizing the disease subsets of idiopathic inflammatory myopathy (IIM).

The MSA/MAA plays an important role in the expert-based (sub)classification measure of IIM. Due to insufficient data pertaining to MSA in large multicenter cohorts, they are understated in subclassification criteria. The role of a biopsy in diagnosis/subclassification of IIM is restricted only to the classification of autoantibody negative IIM and IBM, and supporting new discoveries on the pathophysiology. Hence consolidated MSA is potentially capable of nullifying other diagnoses of IIM such as biopsy in immune-mediated necrotizing myopathies and dermatomyositis. The diverse analytical and clinical performance characteristics of the present commercially accessible assays for the identification of MSA/MAA may influence the diagnostic and prognostic classification of IIM. Moreover, such limitations may impair the design of prospective multicenter studies on MSA/MAA and their optimization for clinical use.

In order to overcome these challenges in MSA/MAA tests, Carolien Bonroy and co-researchers, have highlighted the need for further validation studies and harmonization of newer approaches for the identification of MSA/MAA from the pre-analytical to the post-analytical phase. They also underscored the need to have increased knowledge on the disadvantages related to the application of commercial MSA/MAA tests in routine use as well as in research. Close collaboration between IIM clinical experts, laboratory professionals, and diagnostic companies is paramount to achieving this objective.

Reference: Bonroy C, Piette Y, Allenbach Y, Bossuyt X, Damoiseaux J. Positioning of myositis-specific and associated autoantibody (MSA/MAA) testing in disease criteria and routine diagnostic workup. J Transl Autoimmun. 2022 Feb 11;5:100148.