Congenital myopathy without specific features (minimal change myopathy).

Three patients including a father and his daughter as well as a sporadic case who had a history of delayed developmental milestones showed symptoms of generalized muscle weakness predominantly in the neck flexors, high-arched palate, slender stature, myopathic face and nasal tone vocalisation. Histological and histochemical examinations on the biopsied muscles demonstrated minimal nonspecific changes; mild variation in fiber size, slight abnormality in fiber type distribution and an increased number of undifferentiated type 2C fibers. The abnormal muscle pathology was assumed to have resulted from delayed muscle fiber growth and differentiation due to a probable defective neural influence upon the developing muscles.