A case of congenital neuromuscular disease with uniform type 1 fibers.

Congenital neuromuscular disease with uniform type 1 fibers is a rare form of congenital nonprogressive myopathy. We report a 3-year-old boy with this disease who showed delayed motor developmental milestones and recurrent acute respiratory failure. He obtained head control at 16 months, crawled at 17 months and sat alone at 20 months, but still could not walk at age 44 months. His mental development was good; he could speak 3-word sentences at 44 months. Scoliosis, bilateral congenital dislocation of the hips, bilateral undescended testes and hemangioma simplex on the right lower limb were also seen. Muscle biopsy at the age of 8 months showed more than 99% of the myofibers were type 1. This is the first case of congenital neuromuscular disease with uniform type 1 fibers accompanied by recurrent acute respiratory failure. This case may be clinically more severe than previously reported cases.