(DI-CMTB) DNM2-Related Intermediate Charcot-Marie-Tooth Neuropathy

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DNM2-Related Intermediate Charcot-Marie-Tooth Neuropathy [internet].

Züchner S.

In: Pagon RA, Bird TC, Dolan CR, s K, editors. GeneReviews [internet].

Seattle (WA): University of Washington, Seattle; 1993-.

2010 Jul 08.

Excerpt

Disease characteristics. DNM2-related intermediate Charcot-Marie-Tooth

neuropathy (DI-CMTB) has a classic, mild to moderately severe

Charcot-Marie-Tooth hereditary neuropathy phenotype that often includes pes

cavus foot deformity, depressed tendon reflexes, distal muscle weakness and

atrophy, and sensory loss. Mean age at onset is 16 years, but ranges from age

two to 50 years. It is unusual for individuals with DI-CMTB to become wheelchair

bound. Other findings include asymptomatic neutropenia and early-onset cataracts

(often noted in childhood before age 15 years).

Diagnosis/testing. The diagnosis is suspected in individuals with typical

findings of CMT hereditary neuropathy and intermediate or axonal motor median

nerve conduction velocities (NCV) ranging from 26 m/s to normal. Diagnosis

requires molecular genetic testing of the DNM2 gene, the only gene known to be

associated with DI-CMTB.

Management.Treatment of manifestations: Treatment of DI-CMTB is symptomatic and

involves evaluation and management by a multidisciplinary team that includes

neurologists, orthopedic surgeons, and physical and occupational therapists.

Treatment may include ankle/foot orthoses; orthopedic surgery; forearm crutches

or canes; wheelchairs; acetaminophen or nonsteroidal anti-inflammatory agents

(NSAIDs) for musculoskeletal pain; career and employment counseling.

Surveillance: regular evaluation by the multidisciplinary team to determine

neurologic status and functional disability.

Agents/circumstances to avoid: all drugs or agents known to be hazardous for

peripheral neuropathies.

Genetic counseling: DI-CMTB is inherited in an autosomal dominant manner. Most

individuals diagnosed with DI-CMTB have an affected parent. The proportion of

cases caused by de novo mutations is unknown. Each child of an individual with

DI-CMTB has a 50% chance of inheriting the mutation. Prenatal diagnosis for

pregnancies at increased risk is possible if the disease-causing allele of an

affected family member is known. Requests for prenatal testing for conditions

(such as DI-CMTB) that do not affect intellect and have some treatment available

are not common.