Charcot-Marie-Tooth disease type 4J

Charcot-Marie-Tooth disease type 4J (CMT4J) is a rare, autosomal recessive hereditary motor and sensory neuropathy caused by mutations in the FIG4 gene (also known as SAC3). This gene encodes a phosphoinositide 5-phosphatase that plays a critical role in the regulation of phosphatidylinositol 3,5-bisphosphate, which is essential for proper endosomal and lysosomal trafficking in cells. CMT4J primarily affects the peripheral nervous system, leading to progressive degeneration of both motor and sensory nerves in the extremities. Clinical features of CMT4J typically begin in childhood, though onset can be variable. Patients commonly present with progressive distal muscle weakness and atrophy, particularly in the lower limbs, leading to difficulty walking and foot deformities such as pes cavus. Sensory loss in the hands and feet, reduced or absent deep tendon reflexes, and asymmetric limb involvement have been reported. The disease can progress to involve proximal muscles and may lead to significant disability. Nerve conduction studies typically show features of both demyelinating and axonal neuropathy, and nerve biopsies may reveal both demyelination and axonal degeneration. Some patients may also exhibit cranial nerve involvement. There is currently no cure for CMT4J. Management is supportive and multidisciplinary, including physical therapy, occupational therapy, orthotic devices, and surgical interventions for skeletal deformities when needed. Pain management may also be necessary. Research into potential therapies, including gene therapy approaches, is ongoing. Early diagnosis through genetic testing is important for appropriate management and genetic counseling for affected families.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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