Evidence of myotonic origin of type 2B muscle fibre deficiency in myotonia and paramyotonia congenita.

Available experimental and clinical evidence strongly suggests that deficiency in type 2B muscle fibres in generalized myotonia and paramyotonia congenita will develop consequent to lasting myotonic activity as its adequate stimulus. Type 2B fibre deficiency need not be regarded as the product of a hypothetical genetic factor.