Congenital hypomyelination neuropathy in a newborn.

A case of infantile neuropathy with signs of respiratory distress and impaired abdominal movements from the neonatal period was reported. Muscle biopsy revealed type II fiber predominance and atrophy, and the sural nerve biopsy demonstrated the absence of myelin in almost all of the axons. Onion bulb formation or myelin debris was not observed. The features of myelin deficit without active myelin breakdown and onion bulb formation, and the finding of muscle pathology, indicating the absence of spinal muscular atrophy, suggested that the case under study was identical to that of hypomyelination neuropathy.