Charcot-Marie-Tooth Neuropathy Type 4H – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY

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NOTE: THIS PUBLICATION HAS BEEN RETIRED. THIS ARCHIVAL VERSION IS FOR HISTORICAL REFERENCE ONLY, AND THE INFORMATION MAY BE OUT OF DATE.

CLINICAL CHARACTERISTICS

Charcot-Marie-Tooth neuropathy type 4H (CMT4H) is a demyelinating form of CMT that is characterized by early onset (usually before age 3 years; range: birth to age 10 years) and slow progression. The degree of distal muscle weakness and amyotrophy varies between affected individuals as does the presence or absence and severity of foot deformities, scoliosis, and sensory involvement. Neuropathic pain has not been reported. To date, findings in18 individuals with molecularly confirmed CMT4H from 13 families have been reported.

DIAGNOSIS/TESTING: CMT4H is suspected in individuals with typical findings of CMT (distal amyotrophy, foot deformities), early onset, and slow progression. Motor nerve conduction velocities (MNCVs) and sensory nerve conduction velocities (SNCVs) are abnormal. The diagnosis is established by the presence of biallelic pathogenic variants.

MANAGEMENT

Often management is by a multidisciplinary team that includes neurologists, physiatrists, orthopedic surgeons, and physical and occupational therapists. Treatment is symptomatic and may include: ankle/foot orthoses (AFOs); physiotherapy (daily heel cord stretching exercises and physical activity to prevent contractures and help preserve flexibility); surgery to correct severe pes cavus deformity and/or spine deformities; and forearm crutches, canes, and/or wheelchairs for mobility. Musculoskeletal pain may be treated with acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs). Regular (annual) evaluation to determine neurologic status and functional disability. Obesity because it makes walking more difficult; medications that are toxic or potentially toxic to persons with CMT.

GENETIC COUNSELING

CMT4H is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk family members and prenatal diagnosis for pregnancies at increased risk are possible if the pathogenic variants in the family have been identified.