Charcot-Marie-Tooth disease (CMT) is the most common hereditary neuromuscular disorder affecting more than 1 in 2500 people. Molecular defects that cause CMT are complex and involve large number of genes. This is the first Canadian study describing results of clinical genetic testing of nearly 3000 patients. This is also the largest patient cohort published to date which had comprehensive CMT testing involving clinical Next Generation Sequencing analysis as well as copy number analysis of all genes of the entire gene panel. Key findings include increased diagnostic rate associated with comprehensive molecular analysis, as well as identification of a large number of novel genetic mutations and copy number alterations associated with this disorder. (By Dr. Bekim Sadikovic, https://jmg.bmj.com/content/early/2020/05/05/jmedgenet-2019-106641 )