As with the other myopathies, nemaline often presents with muscle weakness and delayed motor milestones. There may be heart and repiratory involvement. In infants with respiratory weakness, early diagnosis and ventilation can help the child over early difficulties and improve prognoses. There is a severe variant of nemaline myopathy with what appears to be a slightly different inheritance. This variant presents with extreme weakness at birth and an often fatal outcome.
Nemaline myopathy appears to have a greater range of severity than some of the other myopathies.
Researchers speculate that the muscle development may be arrested in these individuals, but this has not been proven. Like the other myopathies, myotubular myopathy often presents in infancy or early childhood with muscle weakness. There may be weakness of the eye and facial muscles. As with the other myopathies, the degree of weakness varies. The disorder is often non-progressive or only slowly progressive.