Defects in SH3TC2 are the cause of Charcot-Marie-Tooth disease type 4C (CMT4C). CMT4C is a recessive form of Charcot-Marie-Tooth disease, the most common inherited disorder of the peripheral nervous system. Charcot-Marie-Tooth disease is classified in two main groups on the basis of electrophysiologic properties and histopathology: primary peripheral demyelinating neuropathy and primary peripheral axonal neuropathy. Demyelinating CMT neuropathies are characterized by severely reduced nerve conduction velocities (less than 38 m/sec), segmental demyelination and remyelination with onion bulb formations on nerve biopsy, slowly progressive distal muscle atrophy and weakness, absent deep tendon reflexes, and hollow feet. By convention, autosomal recessive forms of demyelinating Charcot- Marie-Tooth disease are designated CMT4. CMT4C is characterized by onset in childhood, early-onset scoliosis and a distinct Schwann cell pathology. Defects in SH3TC2 are the cause of mononeuropathy of the median nerve mild (MNMN). A disease characterized by median nerve mononeuropathy at the wrist. The clinical presentation ranges from a mild phenotype, consistent with carpal tunnel syndrome, to a severe median nerve mononeuropathy at the wrist associated with evidence of a more widespread axonal polyneuropathy. The latter phenotype is similar to that of patients with hereditary neuropathy with liability to pressure palsies. 4 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.