Manifesting pediatric carrier of isolated dystrophinopathy with initial presentation of myalgia and persistent hyperCKemia.

Dystrophinopathy is caused by mutations in the dystrophin gene at Xp21. Although manifesting carriers of dystrophinopathy have been documented in adults, symptomatic dystrophinopathy in female children is rare. We report on a 13-year-old girl with initial presentation of myalgia at age 7 years and an incidental finding of increased transaminases and creatine kinase at regular health check at age 12 years. At age 13 years, manual muscle testing revealed asymmetric bilateral proximal weakness of extremities. Slight calf hypertrophy and winged scapulae were found. Muscle biopsy revealed a mosaic pattern in dystrophin immunostaining. Mutation analysis of the dystrophin gene revealed a novel de novo c.1150-2delA mutation. Accordingly, the patient was found to be an isolated dystrophinopathy carrier, manifesting limb-girdle pattern of muscle weakness in her childhood. This report suggests that dystrophinopathy should always be considered in female patients with sporadic myopathy. Dystrophin immunostaining and mutation analysis for the dystrophin gene are necessary for final diagnosis, subsequent genetic counseling, and long-term care.