Improvement of DIAgnostic and Phenotype-genotype Correlation Studies in Patients With MYOpathy Suspected of TITinopathy

Due to the widespread use of NGS, TTN is emerging as a major causative gene in neuromuscular disorders, with high clinical heterogeneity. The mechanisms underlying the phenotypic variability and mode of inheritance (recessive or dominant) of titinopathies are poorly understood. They involve the primordial structural functions of titin on the formation and stability of the sarcomere, as well as its interactions with other proteins. We identified by NGS, in patients with skeletal myopathy (with or without cardiomyopathy), several potentially disease causing TTN variants. The specific aims of the present project are to implement functional studies (transcripts, protein analyses, in vitro protein-protein interaction studies) to evaluate the effect of TTN variants on the transcripts and protein in order to perform phenotype-genotype correlation studies. We participate to the national "titin network" and to international efforts for the understanding of the molecular bases of titinopathies. Genomic characterisation opens the way to develop cellular models of titinopathy, derived from patient biopsies. This is also a mandatory first step for the design of novel therapeutic approaches.