Immunocytochemistry is playing an increasingly important role in the field of congenital
myopathies. It is not yet the diagnostic tool that it is for the
muscular dystrophies, but nevertheless it provides useful information on the nature of the structural defects that define each congenital
myopathy, and on the additional secondary changes that accompany them. Immunocytochemistry may have a role in identifying primary
protein defects but this may be dependent on the effect of a mutation on
protein expression. Mutations affecting function, rather than expression, of a
protein may not be detected by immunocytochemistry. Studies of candidate
proteins, such as
nebulin in
nemaline myopathy, and the
ryanodine receptor in
central core disease, are, however, in progress, and as more defective genes are identified, and
antibodies become available, immunocytochemistry will have an increasingly important role. Myofibrillar components are frequently affected in congenital
myopathies and immunocytochemical localisation of their
isoforms can reveal the nature of the structural abnormalities, such as rods, cores, and a variety of inclusions. Developmentally regulated
proteins such as
myosin heavy chains and intermediate filaments are also relevant to the understanding of the maturational process, in particular in myotubular/
centronuclear myopathies, and also to the plasticity of muscle fibre types. Immunocytochemistry will continue to play an active role in studies of congenital
myopathies and provide insight into their pathogenesis.