RYR1 and congenital myopathy with cores: Additional abnormalities on oxidative staining (generally considered to be more specific for RYR1-related congenital myopathies) were observed in 52% of cases, and included unevenness (or ‘moth-eaten appearance’) (n = 24; 48%), central cores (n = 7; 14%), or multiple minicores (n = 3; 6%).