Biomarkers of inclusion body myositis.
OBJECTIVE
Inclusion body myositis (IBM) is a poorly understood autoimmune and degenerative disorder of skeletal muscle. Here, pathophysiological and diagnostic biomarkers of IBM are reviewed.


RESULTS
Muscle histopathological biomarkers have been successful in stimulating the study of IBM pathophysiology for over three decades. Their use as diagnostic biomarkers, in contrast, has significant limitations. A blood biomarker, autoantibodies against a 43-kDa muscle protein reported in 2011, has now been identified as targeting cytoplasmic 5' nucleotidase (cN1A; NT5C1A), a protein involved in nucleic acid metabolism. Diagnostic testing for these autoantibodies is of high diagnostic performance for IBM.


CONCLUSIONS
Muscle biomarkers have suggested that IBM pathophysiology is linked to myonuclear degeneration and disordered nucleic acid metabolism. A blood biomarker has high diagnostic performance for IBM, and through identification of its target links, IBM autoimmunity and degeneration together, supporting the view that IBM pathophysiology includes abnormal nucleic acid metabolism.
Department of Neurology, Harvard Medical School, Division of Neuromuscular Disease, Brigham and Women's Hospital, Children's Hospital Informatics Program, and Harvard-Massachusetts Institute of Technology, Division of Health Sciences and Technology, Boston, Massachusetts, USA.
Steven A
SA
Greenberg
D015720:5'-Nucleotidase / Q000276:immunology; D001323:Autoantibodies / Q000097:blood; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis*; D006801:Humans; D018482:Muscle, Skeletal / Q000737:chemistry; D018979:Myositis, Inclusion Body / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology
D001323:Autoantibodies; D015415:Biomarkers; D015720:5'-Nucleotidase; C552626:NT5C1A protein, human