Authors: Heinz Jungblutha, Mark R. Davis, Clemens Müller, Serena Counsell, Joanna Allsop, Arijit Chattopadhyay, Sonia Messina, Eugenio Mercuri, Nigel G. Laing, Caroline A. Sewryb, Graeme Bydder, Francesco Muntoni
Mutations in the skeletal muscle ryanodine receptor (RYR1) gene are associated with a wide range of phenotypes, comprising central core disease and distinct subgroups of multi-minicore disease. We report muscle MRI findings of 11 patients from eight families with RYR1 mutations (nZ9) or confirmed linkage to the RYR1 locus (nZ2). Patients had clinical features of a congenital myopathy with a wide variety of associated histopathological changes. Muscle MR images showed a consistent pattern characterized by (a) within the thigh: selective involvement of vasti, sartorius, adductor magnus and relative sparing of rectus, gracilis and adductor longus; (b) within the lower leg: selective involvement of soleus, gastrocnemii and peroneal group and relative sparing of the tibialis anterior. Our findings indicate that patients with RYR1-related congenital myopathies have a recognizable pattern of muscle involvement irrespective of the variability of associated histopathological findings. Muscle MRI may supplement clinical assessment and aid selection of genetic tests particularly in patients with non-diagnostic or equivocal histopathological features.
Keywords: Muscle MRI; RYR1 gene; Central core disease; Multi-minicore disease