Non-invasive protein analysis in the first dysferlinopathy Croatian families

Abstract Mutations in human dysferlin (DYSF) gene cause both limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM), also named dysferlinopathy. They are autosomal recessive muscular dystrophies characterized by degeneration and weakness of proximal and/or distal limb girdle muscles caused by partial or complete absence of a sarcolemmal protein dysferlin. The size and large mutational spectrum of DYSF impose a multistep diagnosis strategy before gene analysis. Here we report the first three patients from two unrelated Croatian families in which diagnosis of dysferlinopathy was suggested on the basis of clinical picture, family history and linkage analysis. In order to confirm the presumed diagnosis, we performed a blood-based assay in which dysferlin expression is screened in blood monocytes. All three tested patients showed complete absence of dysferlin expression, giving strong evidence of dysferlinopathy that was recently confirmed by mutation analysis. In conclusion, we would suggest the presented diagnostic strategy as a reliable and non-invasive method to be used as an alternative to muscle tissue protein analysis in routine diagnostics of dysferlinopathies, prior to the more complex and demanding search for causative DYSF mutations. This non-aggressive approach seems especially useful in situation in which multiplex Western blot (WB) analysis of different muscular dystrophy proteins on muscle sample is not available.