Congenital myopathy with reduced type 2 muscle fibers

Definition

A rare congenital myopathy characterized by neonatal onset of severe muscle weakness with selective atrophy/hypotrophy or absence of type II myofibers. Patients present at birth with hypotonia and respiratory failure, as well as mild facial and severe axial and proximal upper and lower limb weakness with areflexia and mild contractures. Eye movements and cardiac function are normal.