a familial type of demyelinating sensorimotor polyneuropathy that begins in early childhood and is slowly progressive; clinically characterized by foot pain and paresthesias, followed by symmetric weakness and wasting of the distal limbs; one of the causes of stork legs; patients are wheelchair bound at an early age; peripheral nerves are palpably enlarged and nontender; pathologically, onion bulb formation is seen in the nerves: whorls of overlapping, intertwined Schwann cell processes that encircle bare axons; usually autosomal recessive inheritance; an autosomal dominant form also exists; both forms can be caused by mutations in the peripheral myelin protein gene 22 (PMP22) on 17q or in the myelin protein zero gene (MPZ) on 1q. SYN: Dejerine disease, hereditary hypertrophic neuropathy, progressive hypertrophic polyneuropathy.