Inherited neuromuscular disorders (NMD) form a group of genetic diseases that result in long-term disability. The total incidence of NMD is greater than 1 in 3,000 and comprises a group of more than 200 monogenic disorders (Emery 1991). For about half of the cases, the molecular cause has not been identified. An extensive clinical evaluation with complementary gene-by-gene testing is often required to reach an exact diagnosis. Due to the presence of genetic heterogeneity and lack of segregation in sporatic cases, reaching a diagnosis is challenging, lengthy, and expensive. The genetic heterogeneity can be demonstrated by the number of genes involved in specific subgroups of NMD, namely, hereditary sensorimotor neuropathies (HSMN; 50 genes) and congenital muscular dystrophies (12 genes; North 2008; Valencia et al. 2013). In other instances, some NMD genes are very large and are not sequenced completely because it is costly and labor-intensive to sequence by the Sanger method. For the patient, this gene-by-gene approach increases the number of tests that are required, thus, delaying the diagnosis and exposing the patient to unnecessary investigations and treatments, precluding the full benefit of a targeted approach to treatment, and increasing recurrence risk in the families (Vasli et al. 2012).
Neuropathy Myopathy Polyneuropathy Ryanodine
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