Titinopathies, are complex neuromuscular disorders resulting from TTN gene mutations with diverse symptoms and inheritance modes. This study focused on eight families with dominant titinopathies. We employed next genetation sequencing on DNA and RNA to identify and characterize TTN gene copy number variations (CNVs). These analyses in patients’ muscles revealed seven deletions CNVs. The prevalent phenotype was distal myopathy with contractures. The study’s integrated clinicobiological data allowed the establishment of new genotype-phenotype associations for titinopathies, primarily distal myopathy. Detecting TTN CNVs enhances diagnostic sensitivity in these complex neuromuscular disorders. (By Dr. Aurélien Perrin, https://jmg.bmj.com/content/early/2023/11/07/jmg-2023-109473 )