Progress and challenges in diagnosis of dysferlinopathy.

Dysferlin-deficient limb girdle muscular dystrophy type 2B, distal Miyoshi myopathy, and other less frequent phenotypes are a group of recessive disorders called dysferlinopathies. They are characterized by wide clinical heterogeneity. To diagnose dysferlinopathy, a clinical neuromuscular workup, including electrophysiological and muscle imaging investigations, is essential to support subsequent laboratory testing. Increased serum creatine kinase levels, distal or proximal muscle weakness, and myalgia with onset in the second or third decades are the main clinical features of the disease. In muscle biopsies, severe dysferlin deficiency by immunoblot or its abnormal localization by immunohistochemistry are the gold standard, as they have a high diagnostic value. Dysferlin testing on monocytes is a valuable alternative to muscle immunoblotting. Molecular techniques for gene mutation detection, such as next generation sequencing, have improved the genetic diagnosis, which is crucial for treatment and genetic counselling. Muscle Nerve 54: 821-835, 2016.