Targeted next-generation sequencing assay for detection of mutations in primary myopathies

Mutations in more than 100 different genes are known to cause hereditary primary myopathies. In patients with less distinct phenotypes several genes may have to be sequenced in order to make the correct diagnosis. The large number of possible candidate genes and overlapping phenotypes, as well as an enormous size of some of the genes such as DMD, TTN and NEB, constitute difficult challenges for molecular genetic diagnostics using conventional sequencing. Molecular characterization is nevertheless important for the final diagnosis and accurate management of the diseases. Targeted next-generation sequencing is a rapid and cost-effective method to sequence large numbers of genes simultaneously. We developed a targeted next-generation sequencing assay, MyoCap, for the coding exons and UTRs of 180 myopathy related genes including 42 novel genes that have not yet been associated with myopathies. DNA samples of four controls with known mutations and 61 patients negative for previous candidate gene approaches were sequenced. The genetic defect was totally or partly clarified in 21 patients with nine of them having potential disease-causing mutations in TTN. MyoCap provides higher read depth and coverage with lower price in the myopathy related genes compared to the whole exome sequencing and is thus very suitable for diagnostic use.