[A rare case of adult-onset Becker muscular dystrophy diagnosed by dystrophin staining].

Different diagnosis of Becker muscular dystrophy (MD) from limb-girdle MD mainly depends on the differences of heredity form and age at onset. However, sporadic cases with either type of MD often occur, and occasionally Becker MD can occur in adult age when limb-girdle MD commonly occurs. We reported the male sporadic case of Becker MD with the onset at 30 year old who was diagnosed by dystrophin staining. At the age of 30, he noticed mild difficulty to stand up and instability when hurrying up stairs. His weakness of lower limb-girdle gradually progressed, but he is able to walk without any support at the present age of 54, and he never showed weakness in upper limbs. Neurological and laboratory examination revealed that severe atrophy of lower limb-girdle, mild calf hypertrophy and moderate elevate of serum CK level. These history and symptoms hardly distinguish between Becker and limb-girdle MD. Immunostaining of biopsy muscle from the patient using the antiserum against synthetic peptide fragment of dystrophin revealed faint and patchy pattern, and immunoblot revealed 380 kd of abnormal size dystrophin. These dystrophin testing confirmed that this case was a rare case of Becker MD with adult-onset and mild clinical course.