Table 1 Classification and distribution of diseases in muscle biopsy cohort

Idiopathic inflammatory myopathy

531

61.7

 Dermatomyositis

346

40.2

 Clinical amyopathic dermatomyositis

75

8.7

 Immune-mediated necrotising myopathy

68

7.9

 Anti-synthetase syndrome

82

9.5

 Polymyositis

32

3.7

 Sporadic inclusion body myositis

3

0.3

Non-idiopathic inflammatory myopathy

253

29.4

 Muscular Dystrophy

66

7.7

  Limb grindle muscular dystrophy 2B

29

3.4

  Other types muscular dystrophy

37

4.3

 Metabolic myopathy

21

2.4

  Lipid storage myopathy

16

0.7

  Mitochondrial myopathy

3

0.3

  Glycogen storage disease

2

0.2

 Endocrine myopathy

13

1.5

  Myopathies associated with hypothyroidism

9

1.0

  Hypokalemic periodic paralysis

3

0.3

  Hypophosphorus rickets

1

0.1

 Neurogenic myopathy

19

2.2

 Other CTD accompanied with skeletal muscle symptoms

62

7.2

 Myopathy induced by external factors

25

2.9

 Asymptomatic hyperCKemia

47

5.5

Undiagnosed

76

8.8

Total

860

100