Pseudometabolic dystrophinopathy without immunohistochemical anomaly

A 9 year old boy suffering from migraines, vomiting and exercice intoleranc e was hospitalized Clinical examination revealed calf hypertrophy only. The re was no muscular deficit and cardiac examination was normal. Creatine kin ase and transaminase were elevated Muscle biopsy revealed fibers of various sizes, centrally located nuclei, occasional necrotic and regenerative fibe rs. Interstitial tissue was normal. Immunohistochemistry with various antib odies directed against the membranous dystrophin complex was normal. Wester n Blot analysis revealed dystrophin of abnormal size, and multiplex PCR con firmed the :dystrophinopathy showing an absence of exon 43 and 44. This obs ervation highlights the occurrence of unusual dystrophinopathies revealed b y exercise intolerance and pseudo-metabolic syndrome. Normal anti-dystrophi n immunostaining does not rule out the diagnosis which may only be made by Western Blot analysis or genetic studies.