Authors present a girl without familiar antecedents of consanguinity with mild motor deficiency, hypotonicity and obesity during infancy, with progressive posterior healing. The girl did not present Marfan's habit or special phenotype, and had small hypertrophy of calfs. There was not recurrent respiratory infections. EMG was myopathic and muscle dependent seric enzymes (CPK, ALD, LDH...) were normal. Radiographically films showed increased relationship fat-muscle and pathology by MO and ME confirmed the presence of small sticks in muscle fibers. After evaluating the case as a neomutation, the genetic counseling is made.