Presentation is usually in infancy with slowly
progressive distal or generalized muscle weakness and atrophy and diminished
or absent deep tendon reflexes. Motor development is delayed. Other clinical
features may include foot dropping (manifesting as frequent tripping), pes
cavus deformity, muscle cramping, steppage or equine gait, “champagne
bottle" or stork legs, hammertoes, and clawhand. Pain and temperature
sensation are normal. The diaphragm, phrenic nerve, and vocal cords are
occasionally involved. Frequently associated with mental retardation and
deafness. Moderate disability in adulthood.