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Generalized hypotonia, thin muscle mass, and mild axial weakness (7)

Muscle biopsy in a 6-month-old boy. Oil red O stain reveals punctate neutral lipid to be more abundant, though not excessive, in type II fibers, a reversal of the normal expected pattern often found in congenital muscle fiber-type disproportion in infancy. This biopsy fulfills all histopathological criteria of congenital muscle fiber-type disproportion and, in the absence of any recognized associated metabolic or genetic diseases, is confirmatory of congenital muscle fiber-type disproportion as an isolated congenital myopathy. Magnification x 250. (Contributed by Dr. Harvey Sarnat.)

Associated Disorders

  • Calpain 3 deficiency
  • Cerebellar hypoplasia
  • Cori-Forbes disease
  • Debrancher enzyme deficiency
  • Emery-Dreifuss X-linked muscular dystrophy
  • Krabbe globoid cell leukodystrophy
  • Mitochondrial cytopathies
  • Moebius syndrome
  • Multiple sulfatase deficiencies
  • Myasthenia gravis, congenital
  • Nemaline rod myopathy
  • PHOX2B mutation
  • Pompe disease
  • Trendelenburg gait
  • Ullrich (collagen VI) muscular dystrophy