has material basis in germline mutation in TTN congenital nervous system disorder neuromuscular disease caused by qualitative or quantitative defects of titin congenital myopathy TTN-related myopathy GARD:0026073 congenital myopathy related to TTN A disorder of the musculoskeletal system caused by pathogenic variants in the TTN gene encoding the titin protein expressed in striated muscle. These variants are associated with a variety of overlapping congenital and adult-onset myopathies characterized by non-progressive or progressive neck, axial, and limb weakness, joint contractures, early-onset respiratory insufficiency, facial weakness, congenital cardiac anomalies and/or early-onset dilated cardiomyopathy. Histologic findings on skeletal muscle biopsy reveal a wide range of structural abnormalities and can include increased internalized and central nuclei, minicores, and dystrophic changes. In the absence of evidence supporting distinct differences in molecular mechanisms between the associated disease entities, as well as considerable phenotypic overlap, these entities can be considered part of a clinical spectrum of TTN-related myopathy. MONDO:0100175 TTN myopathy hereditary neurological disease