Dysferlinopthy refers to a group of autosomal recessive muscular dystrophy caused by mutations
of dysferlin gene (DYSF). The DYSF is located on chromosome 2p13, contains 55 coding exons and
spans 150 kb of genomic DNA. The transcript is 6.3 kb large and is mainly expressed in skeletal muscle
at the sarcolemmal membrane. Dysferlin is a key calcium ion sensor involved in the Ca2+-triggered
synaptic vesicle-plasma membrane fusion process, and plays a role in the sarcolemmal membrane
repair mechanism of skeletal muscle fibers that permits rapid resealing of membrane disrupted by
mechanical stress. Three main clinical subtypes of dysferlinopathy consist of Miyoshi myopathy (MM),
limb-girdle muscular dystrophy type 2B (LGMD2B), and distal myopathy with onset in tibialsis anterior
(DMAT). Regardless of their clinical phenotype, patients with dysferlinopathy share common features
such as onset in late teens to early twenties, slow progression, extremely high serum CK levels, and
loss of dysferlin on immunohistochemistry (IHC) and Western blot (WB). Muscle imaging is helpful for
the evaluation of the degree of affection in different muscle groups and monitoring the progression of
the disease. On muscle biopsy, it is frequently associated with inflammatory cellular infiltrates, and
should be differentiated from polymyositis in order to avoid unnecessary treatment. IHC or WB is the
golden standard for the diagnosis of dysferlinopathy. Although DNA test for the identification of DYSF
mutations can further help to confirm the disease, high risk of diagnostic errors related to the large gene
size can limit its usefulness as a reliable diagnostic test.

KEYWORDS : Dysferlin, Miyoshi myopathy, Limb-girdle muscular dystrophy type 2B, Distal myopathy with onset in tibialis anterior