Dysferlin mutations in LGMD2B, Miyoshi myopathy, and atypical dysferlinopathies

Abstract

DYSF encoding dysferlin is mutated in Miyoshi myopathy and Limb-Girdle Muscular Dystrophy type 2B, the two main phenotypes recognized in dysferlinopathies. Dysferlin deficiency in muscle is the most relevant feature for the diagnosis of dysferlinopathy and prompts the search for mutations in DYSF. DYSF, located on chromosome 2p13, contains 55 coding exons and spans 150 kb of genomic DNA. We performed a genomic analysis of the DYSF coding sequence in 34 unrelated patients from various ethnic origins. All patients showed an absence or drastic decrease of dysferlin expression in muscle. A primary screening of DYSF using SSCP or dHPLC of PCR products of each of 55 exons of the gene was followed by sequencing whenever a sequence variation was detected. All together, 54 sequence variations were identified in DYSF, 50 of which predicting either a truncated protein or one amino-acid substitution and most of them (34 out of 54) being novel. In 23 patients, we identified two pathogenic mutations, while only one was identified in 11 patients. These mutations were widely spread in the coding sequence of the gene without any mutational "hotspot."

Unmasking Potential Intracellular Roles For Dysferlin through Improved Immunolabeling Methods

“…Inheritance is autosomal recessive, and disease-causing mutations have been identified across the DYSF gene (Nguyen et al 2005). Since its discovery, dysferlin has been referred to as a plasma membrane protein that is also found in cytoplasmic vesicles (Anderson et al 1999;Bansal et al 2003), largely because it appears enriched at the sarcolemma in cross sections of snap-frozen, unfixed muscle.…”

Limb-girdle muscular dystrophy type 2B mimicking polymyositis

“…The classical phenotype of LGMD type 2B is proximal muscular weakness and atrophy, but some phenotypic variants of this disease and others dysferlinopathies have been described 1,8,9 . Some of them are associated with new mutations in the dysferlin gene 10 .…”

Diagnosis of the Muscular Dystrophies

“…The single section WB technique (Cooper, Lo et al 2003) has been an important advance on traditional methods by significantly reducing the amount of muscle biopsy used for each blot, from 20 -100 mg down to one 8 m cryosection. WB analysis has been found to be more effective for diagnosis than IHC for several forms of LGMD, such as LGMD2B (dysferlin) (Vainzof, Anderson et al 2001;Nguyen, Bassez et al 2005;Lo, Cooper et al 2008), LGMD1C (caveolin-3) (Minetti, Sotgia et al 1998;Carbone, Bruno et al 2000;Herrmann, Straub et al 2000;Lo, Cooper et al 2008) , Becker MD (dystrophin) (Voit, Stuettgen et al 1991) and arguably the alpha-dystroglycanopathies (Peat, Smith et al 2008). However the sensitivity and specificity of WB is relatively poor for LGMD2A (calpain-3) (Fanin, Fulizio et al 2004;Saenz, Leturcq et al 2005;Groen, Charlton et al 2007;Lo, Cooper et al 2008) and the laminopathies (Menezes et al 2011).…”