Fiber type disproportion in nemaline myopathy

A 21-year-old female with nemaline myopathy and concomitant dysmorphism characteristic of elongated face, high arched palate, scoliosis and pes cavus is reported. Neurological examination revealed mild bilateral facial weakness, moderate proximal muscle weakness, and generalized absence of deep tendon reflexes in all limbs. Electromyography disclosed a moderate amount of fibrillations and positive, and short duration polyphasic waves. A biopsied specimen, obtained from the vastus lateralis muscle, showed abundant nemaline bodies from pathological study, and electron dense particles on Z-line by electron-microscopic examination. In addition, a twin-peaked population curve in fiber diameter, selective type 1 muscle fiber atrophy (34.3 um +/- 8.7 um in diameter) as well as type II fiber hypertrophy (117.0 +/- 55.8 um in diameter), and type 1 fiber grouping were observed. We report the case and raise another important clue of fiber type disproportion in the diagnosis of nemaline myopathy.