[Pseudometabolic distrophinopathy without immunohistochemical anomaly]

A 9 year old boy suffering from migraines, vomiting and exercise intolerance was hospitalized. Clinical examination revealed calf hypertrophy only. There was no muscular deficit and cardiac examination was normal. Creatine kinase and transaminase were elevated. Muscle biopsy revealed fibers of various sizes, centrally located nuclei, occasional necrotic and regenerative fibers. Interstitial tissue was normal. Immunohistochemistry with various antibodies directed against the membranous dystrophin complex was normal. Western Blot analysis revealed dystrophin of abnormal size, and multiplex PCR confirmed the dystrophinopathy showing an absence of exon 43 and 44. This observation highlights the occurrence of unusual dystrophinopathies revealed by exercise intolerance and pseudo-metabolic syndrome. Normal anti-dystrophin immunostaining does not rule out the diagnosis which may only be made by Western Blot analysis or genetic studies.