VP.06 A new case of congenital myopathy related to TNNC2

Our knowledge of congenital myopathies is expanding. Recent genes have been identified in troponin variants, among them only 2 families with TNNC2 mutations have been described. We report an 18 yo man with a severe neonatal congenital myopathy that slowly improved over time. He was born with significant hypotonia and feeding difficulties. He was fed through a gastrostomy until 5 years of age. He walked independently at 4 yo. He is now able to ride a mountain bike on a regular basis. His physical examination showed a distal more than proximal weakness in upper limb and a more pelvic girdle weakness in lower limbs. Striking features include mild oculoparesia and hypomimic face with high arch palate. CK levels were normal. Two EMGs showed nonspecific myopathic features. Muscle biopsy demonstrated nonspecific moderate myopathic features. Interestingly, muscle MRI showed very discrete fatty infiltration in the thigh. Next generation sequencing panels for dystrophic and non-dystrophic myopathies were negative. Whole exome sequencing identified a novel heterozygous mutation c.204 C>A in TNNC2. This case expands the clinical phenotype of patients with congenital myopathy related to TNNC2.