Delineating the phenotypes of early onset myopathy due to novel titin gene mutations

Cases of early onset myopathy due to titin (TTN) gene mutations are rare. We describe three patients, including two siblings, with novel TTN gene mutations. The first is a 9-year-old girl, with normal early motor and cognitive development, who developed weakness by the age of 3 years. She had grade 4/5 power of the shoulder and pelvic girdles, joint laxity, mild calf hypertrophy, lumbar lordosis and waddling gait. Echocardiography revealed...