Diagnosis:
Genetic testing confirms the diagnosis, as does muscle biopsy
Muscle biopsy:
Early: variation in fibre size, atrophic fibres, round hypertrophied fibres, centronucleation, regenerating fibres, split fibres. Endomysial connective tissue begins to appear.
Later: infiltration by adipose tissue. Poor differentiation of fibre type on ATPase reactions.
Inflammatory infiltrates may occur.
Immunohistochemistry: total absence of dystrophin (antibodies to C terminal are more specific). Normal expression of spectrin. Confirms the diagnosis.
Quantitative dystrophin analysis by Western blot: markedly decreased or absent dystrophin. Confirms the diagnosis.
Genetic:
X linked recessive
Clinical features:
Onset 3-10 years, Progressive
Proximal lower limb weakness, neck flexor weakness.
Preserved neck extensors, face and ocular muscles
Preservation of ankle reflexes, other reflexes are depressed
Pseuohypertrophy of calf muscles (and sometimes deltoids), Gower’s manoeuvre on standing.
Treatment:
Prednisolone P.O. or deflazacort P.O.
Creatine monohydrate
Preserve ambulation