A 9 year-old girl was admitted with complaints of slow, progressive proximal limb weakness that started 1 year prior. Until the age of 8, she had grown up without abnormality, developed a normal walking course, and normal cognitive function. There was no familial history of neuromuscular disease, including her elder brother. Upon neurological examination, she showed normal intelligence and no cranial nerve abnormality. However, her bilateral limb-girdle muscular power decreased (right arm abductor, arm elevator, arm adductor, forearm flexor, forearm extensor G4⁺/left arm abductor, arm elevator, arm adductor, forearm flexor, forearm extensor G4°/right hip flexor, hip extensor, knee flexor, knee extensor G4°/left hip flexor, hip extensor, knee flexor, knee extensor G4⁺). Gower signs and bilateral calf muscle pseudohypertrophy were also observed. Liver enzymes, serum CK, lactate dehydrogenase, and aldolase were elevated (AST: 97 IU/L; ALT: 225 IU/L; and CK: 456 1 U/L, CK-MB 225 U/L, LDH 1714 IU/L, and Aldolase 16.4 U/mL). The patient also showed normal findings for viral hepatitis markers and arterial blood gas analysis. Electrocardiography and cardiac echocardiography showed no abnormal findings. An electromyography study revealed spontaneous activity (positive sharp waves) and short duration polyphasic potentials in voluntary contraction. We carried out a muscle biopsy on the left vastus lateralis muscle because limb-girdle muscular dystrophy was suspected as the patient was female and did not have a familial history of DMD. The expression of dystrophin protein showed mosaic patterns on a dystrophin immunohistochemical stain from a muscle biopsy (Fig. 1). The other immunohistochemical stain for detecting limb girdle muscular dystrophy and congenital myopathy revealed no abnormality. Accordingly, she was diagnosed as a DMD carrier.

A 32 year-old woman was admitted with complaints of progressive limb weakness that started 9 years prior. She had 2 sons who were diagnosed by exon duplication (exon 52, 53, 56-61) with DMD. On a neurological examination, she showed intellectual disability (IQ = 70) and her bilateral upper extremities, especially scapulohumoral lesion, showed muscular weakness (right arm abductor, elevator, adductor G4°/left arm abductor, elevator, adductor G4⁺). The power of other muscles was within a relatively normal range. Gower signs and bilateral calf pseudohypertrophy were not observed. Serum CK was mildly elevated (CK: 3708 U/L). Cardiac echocardiography showed normal findings, but ECG findings revealed the R/S > 1 in Vl, 2 leads, and deep Q wave in I, V4-6 leads. An electromyography study revealed spontaneous activity (fibrillation and positive sharp waves) and short duration polyphasic potentials in voluntary contraction. A conventional multiplex polymerase chain reaction (PCR) had negative findings, but a multiplex ligation-dependent probe amplification (MLPA) revealed exon duplication at exon 52, 53, 56-61.

A 34 year-old woman was admitted with complaints of progressive weakness in both legs that started 6 years prior. She had 2 sons, who were diagnosed by exon deletion (exon 43, 44 and 45) with DMD. On a neurological examination, she showed intellectual disability (IQ = 78) and her bilateral lower extremities showed muscular weakness (right hip flexor, hip extensor, knee flexor, knee extensor G3°/left hip flexor, hip extensor, knee flexor, knee extensor G4^-). The power of the other muscles was within a relatively normal range. Gower signs and bilateral calf pseudohypertrophy were not observed. Serum CK was mildly elevated (CK: 1289 U/L). Electrocardiography and cardiac echocardiography showed no abnormal findings. An electromyography study revealed spontaneous activity (fibrillation and positive sharp waves) and short duration polyphasic potentials in voluntary contraction. A conventional multiplex PCR had negative findings but a MLPA revealed exon deletion at 43, 44 and 45.