NT5C1A and systemic lupus erythematosus: The sensitivity of anti-cN1A in IBM significantly varies in different studies, ranging from 33% to 76%, mainly due to different detection methods and cut-off thresholds; specificity ranges from 87% to 100%, even though anti-cN1A Abs were also found in the sera of patients with other IIMs and other autoimmune diseases (mainly systemic lupus erythematosus and Sjögren syndrome) [101,102,103,104].