RIG-I expression in perifascicular myofibers is a reliable biomarker of dermatomyositis

Table 1 Summary of the results

	Diagnosis	Perifascicular atrophy^a	Perifascicular atrophy (2 rows)	RIG-I+	Total
Inflammatory myopathy (n = 71)	DM	16 (36%)	11 (25%)	22 (50%)	44
	PM	0 (0%)	0 (0%)	0 (0%)	16
	IBM	0 (0%)	0 (0%)	2 (33%)	6
	IMNM	0 (0%)	0 (0%)	0 (0%)	5
Overlapped myopathy (n = 26)	ASS^b	7 (88%)	1 (13%)	1 (13%)	8
	RA	0 (0%)	0 (0%)	1 (50%)	2
	SLE	1 (50%)	1 (50%)	1 (50%)	2
	SSc	3 (60%)	2 (40%)	1 (20%)	5
	Sjögren	1 (20%)	0 (0%)	0 (0%)	5
	MCTD	1 (25%)	1 (25%)	1 (25%)	4
Muscle dystrophy (n = 8)	Dysf	0 (0%)	0 (0%)	0 (0%)	4
Muscle dystrophy (n = 8)	FSHD	0 (0%)	0 (0%)	0 (0%)	4
Total		29 (28%)	16 (15%)	29 (28%)	105

Healthy controls were excluded from this analysis. DM dermatomyositis, PM polymyositis, IBM inclusion body myositis, IMNM immune-mediated necrotizing myopathy, ASS anti-synthetase syndrome, RA rheumatoid arthritis, SLE systemic lupus erythematosus, SSc scleroderma and scleromyositis, MCTD mixed connective tissue disease, Dysf dysferlinopathy, FSHD fascioscapulohumeral muscle dystrophy. ^aPerifasicular atrophy includes one or more rows of atrophic muscle fibers. ^bThe group of ASS patients was established by the presence of anti-Jo-1 antibodies

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